# Custom monocoque trike



## Darxus (May 10, 2010)

Update 2012-06-15

Project page, with all the pictures: http://www.eternalmachinery.com/ecar/

I recommend starting at the last page of this thread to see if anything interesting has been going on.

Riding motorcycles made me realize how unnecessarily cumbersome cars are. But cars have a couple nice advantages, like keeping the rain off. I'd like to build some kind of minimal vehicle with two seats that I could commute in - 35.2 miles each way, and they recently put in charging stations at work. Minimal frontal surface area, weight, drag. I've done a lot of inconsistent babbling about different possibilities here. I have basically no relevant experience, so this would involve a lot of learning. My goals are unreasonable. People with far more reasonable goals give up all the time, so I recognize it's entirely possible I'll never build anything. Most recently I've been thinking something simpler and easier yet still extreme might be good (this thing is tiny):










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Update 2011-03-16









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Range goal: 100 miles (70 mile commute round trip + headroom).
Aluminum monocoque body, TIG welded by me (I've never welded).
NetGain Impulse 9 motor.
12 6v Trojan T-105s = 10 kWh, in pontoons.
Rear wheel drive.
Even weight distribution per tire.
Motorcycle rear end.
Custom double wishbone front end with push rod actuated inboard coilovers and sway bar. 
Front center of rotation about 2" below ground (single rear = ground level rotation center).
Clearance: 6" (high, for aerodynamics).

http://www.eternalmachinery.com/ecar/

Original post:
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Motorcycles made me realize how incredibly unnecessarily cumbersome most cars are. 

Height: 89 centimeters (35 inches).
Length: ~4.3 meters (14 feet).
Width: ~2 meters (6.5 feet).

Seating capacity: 2.

Based on this kit:
http://evolveelectrics.com/72%20Volt%20Lithium%20Electric%20Motorcycle%20Kit.html

22 Thunder Sky 90 amp lithium cells (yellow) (very interested in suggestions).



















Not shown is the vertical sheet of metal running most of the length of the car on both sides for structural support. Same concept as the Lotus 25 (first F1 monocoque). 

I am very interested in suggestions. I'm far from solidifying anything. Except maybe the seating position and wheel layout. It might be possible to talk me into a tube frame. 


My commute is about 30 miles. I want a range of about 100. I actually got a poll at work including asking if I'm interested in ability to charge my car, but of course not counting on that happening.

I need to read up more on the watt hours and ranges of existing vehicles.

Motors generally are listed with maximum volts or something. And that seems to be based on some often unmentioned amount of amps. So am I right in thinking the actual maximum ratings of motors are more related to watts (which I realize is volts x amps)?

I was thinking four wheels, then realized / remembered how much less gearing is involved with one rear wheel. I want something that's less maintenance than a chain, capable of handling more power than a belt, and less inefficient than a shaft or hydraulic final drive. Surely using gears for the final drive would be somehow bad (even if I mounted the motor on the swingarm near the frame).

I've also thought about two wheels - less resistance. But I think the convenience of low speed stability is worth the extra wheel.

Tilting is tempting. "Cars lean the wrong way in turns." But I think with this geometry, tilting wouldn't gain me much.

I want to wrap the upper (suspension) wishbones and steering rods in fairings. 

It would end up getting registered as a motorcycle due to having three wheels. I'm not sure how difficult it'll be to register in New Hampshire, US, but I think not too bad.

Where can I get wheels / tires around 26" tall and 3" wide, and 30" tall and 6" wide?

I have effectively no experience, but this is all stuff I'm very interested in learning. And I realize figuring out how to get sheet aluminum into that shape and welding it together is a lot of learning. Anything I should know about, other than hammering and English wheels? I don't even have any idea what type or thickness of aluminum is appropriate.


The grey box in the middle of the front suspension is the charger.

Of course I'd prefer a custom molded canopy, but I think cutting flat sheets of safety glass (worst case: cut up used car windows) is going to be _much_ more obtainable.

I'm thinking motorcycle type handlebars, with a single rod running to a lever attached to the steering (old(?) drag racer style), and motorcycle type (un-powered disk) brakes. Doing three independent brakes is tempting (one for each foot, one at the left hand, accelerator at the right hand) for control, but I think I'd prefer just doing a single brake pedal and an accelerator pedal for convenience.

I've been playing with related ideas for a few years: http://www.eternalmachinery.com/


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## toddshotrods (Feb 10, 2009)

I would be the last person to tell someone they can't do something (I live by the anything is possible philosophy) but you are talking a HUGE step; for any type of automotive project. You said you are willing to learn, so it is possible. With your experience/knowledge level, you will spend _much_ more time learning than you will building. There are a handful of scratch-built, and serious custom, projects here on the site. I would recommend you read the entire threads of each before you do anything. You'll not only see the vehicles being built, but kind of experience the challenge from the builder's perspective. Pay attention to post dates. Many times you will see long gaps between posts. Sometimes it just takes a while to catch your breath; sometimes it's figuring stuff out, finding stuff, etc.

Any scratch-built, or serious custom, project is an enormous challenge; mixing the EV aspect in doubles the complications and hurdles. I'm not trying to discourage you, just prepare you. The worst thing in the world is getting knee-deep in a dream project, only to find it's a nightmare, and running out of drive. You can find them in classifieds year-round, every year. You'll see phrases like, lost interest, no time, been sitting for months/years, etc. That usually means it wasn't what they expected, and they're bailing out. The TV shows make it look glamorous, and the challenges almost fun to overcome. In reality, even in multi-million dollar shops, it is incredibly exhausting at times.

All that being said (can't say you weren't warned ) - it is the greatest experience ever!  I've been doing custom work for nearly three decades, and am in the midle of my first scratch-built project. In my thread, I said a few times that it will likely be my last - no way! I already have ideas of what I would do next, and none of them go back to simple modifications of pre-existing vehicles. If I were to use one, it would still be scratch-built except for the original shell. In fact, I even started another one already - an e-bike!


My race rod project.
My e-bike.
Coolest tractor ever.
Coolest bug ever.
Exotic concept.
Go kart.
Three-wheeler (what happened to him?).
Ground-up Trike (had to go back to pg 23 to find it!)
You can also watch some of the conversion threads to see the hurdles they faced, and how much effort went into solving the issues. That'll give you an idea of what just building an EV takes. Just try to be honest with yourself about how far you're willing to go/how much drive you'll have when it's gets _challenging_.

Regarding your specific plans, rolling and shaping a metal body like you have planned is pretty intense. That is a serious craft to learn in and of itself, and you're planning to try to learn and master it while building an EV from scratch - big bite, don't choke! There are fiberglass belly tanker bodies that would put you in the neighborhood. Google it - one company that I know has them is Rod-n-Race. I have no experience with them, have considered purchasing from them but didn't, heard good and bad reviews from previous customers...

Automotive glass is a pain to deal with. The windshields _can_ be cut, but even really experienced glass shops will tell you no guarantee - it might break. Don't even think about cutting the other windows - unless you like sweeping up tons of glass chips! Tempered glass can't be cut, it shatters.

If you have motorcyle type steering on a vehicle that size, it's probably going to be VERY heavy! An automotive rack-and-pinion, and steering wheel, would be better.

That doesn't look like nearly enough batteries to get decent range, and I wouldn't want them between my legs!


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## Darxus (May 10, 2010)

toddshotrods: Thanks for taking the time to reply. I realize this plan is ridiculous. But I fail at avoiding taking things to extremes. There's nothing short of this I'm interested in doing. 

And I think attempting to make an aluminum monocoque should make a fine hobby for a couple years. Maybe without compound curves, and using a fiberglass nose and tail - I need to see what that looks like. And then the batteries will cost less.

I have read through the turmoil of a number of complete custom ICE builds, and some electric conversions, for years.

Thanks for the term "belly tanker", some sexy stuff. Looks like Rod-n-Race is in the middle of a web site move, and not in archive.org.

I guess I don't see why the steering would be heavier than a big motorcycle. Heh, perhaps because motorcycle steering works entirely differently.


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## Duncan (Dec 8, 2008)

Hi Darxsus

Go for it - making it yourself is fun

Have a look at Human Powered Vehicles and Solar cars for how to go fast with minimum power.

A couple of points
Non leaning vehicles - look at height of center of mass and vehicle track
For decent cornering you need to be low or wide

Low is frightening on the road, do you need to know what company makes truck diffs?

A leaning machine can be narrow and high

What is wrong with belt drives? I have seen some transmitting several hundred horsepower 

A folded aluminium or sandwich chassis would go down well, for the body parts have a look at the mould-less fiberglass system Burt Rutan used on the LongEze


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## toddshotrods (Feb 10, 2009)

Duncan said:


> ...Low is frightening on the road, do you need to know what company makes truck diffs?...


That's priceless! 



Darxus said:


> ...I realize this plan is ridiculous. But I fail at avoiding taking things to extremes. There's nothing short of this I'm interested in doing...


Good, we speak the same language. If I don't kick the bucket, I'll be around to help you find the best way there (extremes). Just wanted to point out the challenges, and see how you responded.



Darxus said:


> ...I guess I don't see why the steering would be heavier than a big motorcycle. Heh, perhaps because motorcycle steering works entirely differently.


Quads, ATVs, four-wheelers (or whatever you want to calll them), and many reverse trikes use handlebars so it can work. I based that suggestion on the fact that you have the battery pack up front and said you want enough batteries for a 100-mile range. I don't know what the actual numbers would be, or even the weight of the batteries you mentioned, it just seems like enough batteries for that much range would come with a weight penalty. That would require more effort to turn the wheels. Even a really fast rack and pinion would give you more leverage.


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## fishguts (Dec 19, 2008)

I'm an electric reverse trike fan so I dig it. Yep, sure will be a ton of work, but if you're persistent you can see it through. Not what I would recommend as a first project, though. But hey, you gotta find your own way. Good to be talking about "years". I'm in the second year of my project.

How about a couple suggestions?...
-The extremely laid back seating position is going to be real uncomfortable I bet. So maybe something a little more upright? You might want to think through how you'll get in and out of it, too.
-Looks like a fairly slippery design and the wheel pants are cool, but I see you have an open suspension which wouldn't be very aerodynamic. I'm not concerned about it on my project, but then I'm not looking for a lot of range, either. So maybe aircraft strut-like suspension parts or cover it?
-Also, the trailing edge of the wheel pants look neat, but they'll probably limit your turning radius if the pants are turning with the wheels. 
-Trikes are considered motorcycles in most places, so your "glass" can be plexi - much easier and cheaper to deal with.
-I wouldn't be surprised handlebars would work out on this. I'm going that route and will be mounting the parts in the next several weeks so can let you know how well it works. I have a rack and pinion out of a 914 Porsche as my plan "B" if I need it.

Do you have a nice, big welding/frame table to lay it all out? Probably going to need one.

Good luck with it. I'm looking forward to seeing it come together.


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## grayballs (Aug 27, 2008)

Try looking here. I'll bet you can find what you want



http://www.toddscanopies.com/


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## TomA (Mar 26, 2009)

Interesting drawing and concept. Its like a two-place bobsled, but even more cramped and uncomfortable... ;^) Seriously, its cool and you should build whatever you want to.

Before you get too far, though, you ought to check out your state DMV to see what the licensing regulations there are for your motorcycle class. In NY, a trike seat has to be 20" off the ground, so your design won't be registerable (or insurable) for the road here. You need to avoid off-road (ATV, motocross bike) parts in a lot of states, too. It would be a shame to build something you couldn't got on the road...

Take a look at (Google) Dave Malewicki's California Commuter trike from about 30 years ago. He was on a similar wavelength as your trike. Its a proven and record-setting design, and plans are still available. Buying a set of them from him would get you a long way up your design learning curve for very little money.

Just my $.02.

TomA


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## Darxus (May 10, 2010)

Web page is: http://www.eternalmachinery.com/ecar/

Yikes, I missed comments.










I've been thinking a lot about aerodynamics. On and off for years. Basically, the consensus seems to be that a teardrop / wing / airfoil shape is the most aerodynamic. I believe, and finally found evidence, that that shape is only used because a pointy leading edge causes _sudden_ and complete loss of _lift_ at varying angles of attack, none of which concerns me. More here:

http://www.eternalmachinery.com/mostaerodynamic/

The human / battery swap was because I was having difficulty with the vertical asymmetry. I'm likely to play with the previous layout more. 

My biggest aerodynamics question is: Is it better to give the air a long, smooth path, or a shorter, still smooth but more sudden path? Specifically as it relates to air flow around my head. I'm guessing for this application it doesn't matter that much. The potential problems are skin drag and boundary layer separation (flow becoming turbulent) over longer distances.

I also squared off the sides to better fit the vertical structural reinforcement panels that go in the sides.


Duncan:

Actually one of the recent steps in this process was looking into the feasibility of creating a highway bicycle for my 35 mile (each way) commute. Turned out I would need to be awful close to a world record holder - and they're on groomed courses.

This design involves _nothing_ between my my butt and the pavement but a single layer of sheet aluminum. The 7" of clearance is negotiable. And I want it as wide as is practical. Maybe I should go a little wider. I'm comfortable with being within licking distance of fast moving pavement. 

I've done motorcycle track days a few times. Good stuff. I once slid across the front straight at Loudon NH, watching my bike spin along with me. It was great fun, seriously. This is relevant in two ways: I really am comfortable within licking distance of fast moving pavement, and I'm really disappointed with the failure mode of motorcycles. A little too much throttle, a little too much lean, and a pavement transition, and suddenly you're on the ground. I felt betrayed.

Thanks for the tip on belt drives. Got any links? I fear a very wide belt would be necessary, and aerodynamically inconvenient.


toddshotrods:

Yup, and you were right about the number of cells. I upped the count to 56 (Thundersky 90 amps), which comes out to 395 pounds. Yikes.


fishguts:

I don't see why the extreemly laid back seating position would be uncomfortable. Maybe I should try sitting in a mockup for a couple hours before I start fabricating. (I'm interested in mockup material suggestions - I probably just need to look for myself at home depot.)

Yeah, I've thought a bunch about front suspension fairings. I've played with a couple possibilities, but keep wondering if it's really worth it. Largely because F1 cars don't seem to bother, although I don't know if that's one of their annoying rules (like outlawing turbines and CVTs because they don't sound as entertaining, really). Also, it's a feature that can wait until absolute last. And minimizing half-sprung mass can be good.

You see I chopped off the trailing edge of the wheel pants (I like that term). Didn't seem worth the un-sprung bulk.

It would be great to be allowed to use acrylic, but I worry it wouldn't take long for it to get annoyingly scratched up by highway gravel. I wonder how well they buff up. Any experience with acrylic windshields? 

I look forward to hearing how your steering turns out. 

I have nothing. Except space and time.


grayballs: Awesome canopy link, thanks.


TomA: 

I think of it as cozy 
I really like the idea of the body panels keeping me snugly in place. 

I actually just emailed the DMV today. Sucks to hear about that 20" limit. 

Thanks for giving me Dave Malewicki's name. I was familiar with the vehicle and looking for it recently for obvious reasons. I also was not aware he was selling kits, good to hear.


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## toddshotrods (Feb 10, 2009)

Darxus said:


> ...I don't see why the extreemly laid back seating position would be uncomfortable...


The problem is you have to look forward at the road, meaning your neck would be bent forward. Could be a strain after a while. Recumbent bikes do it though. Every person is different. I like being tucked in a crouching position on motorcycles, while some people would find it extremely uncomfortable...


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## Duncan (Dec 8, 2008)

Hi Darxus
I used to ride a recumbent HPV (Human powerred vehicle) but it was a two wheeler the few times I borrowed a trike it was great fun but very physical
With a couple of inches ground clearance (the chain goes under your bum) you have to lean your body into the corners and you are so low that other road users can't see you

A leaning machine is better and becomes more stable the higher it is
Saying that I can relate to the wheel going away from under you and the bum hitting the road - better than the head!

A leaning three wheeler should avoid that the failure would be a skid

The racing HPV's are normally very low but going higher and having just the wheels below the beast will not have a big drag penalty 

Wheel spats
If you are serious about low drag you need to look at the solar racers
If you have a shape that the flow doesn't separate from (stream-lined) then the old CD x area no longer applies
At this stage it is the "wetted area" 
So it is better to go wider and build everything into your aero-body

Getting a decent body is not that difficult - the devil is in the details around the holes for the wheels and canopy 

How long were you allowing for your commute?
The HPV record is now over 50mph - normal bikes its about 35mph

It would not take much power assist to get a semie-streamlined HPV to cruise at 35+mph
(Two wheeler HPV with nose and tail fairing)
A fit guy (not me) could do it by pedal power

Angle of Recline 
Much better than the face down method the motorbikes use
You will need a head rest - or neck muscles like a bull

You really have three ways to go here

light weight (50lbs) low power 50 - 150 watts
pedal + electric
or
200+ lbs, 400+ watts light weight electric+ 
or
Mini Car
1000+ lbs, 30+Kw


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## Darxus (May 10, 2010)

toddshotrods said:


> The problem is you have to look forward at the road, meaning your neck would be bent forward.


Ah, thanks. Laying flat in bed with just my head propped up while using a laptop for hours makes my throat sore from the angle. I think sitting up this much wouldn't be a problem. Definitely worth considering, and testing.


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## Darxus (May 10, 2010)

*titling and inspection requirements in New Hampshire*

Less than twenty-four hours for a response from the NH DMV: 



> If your looking for certain specifications there are two websites you can refer to. They are
> www.gencourt.state.nh.us/rules/state_agencies/saf-c3200.html and
> www.gencourt.state.nh.us/rsa/html/indexes/default/asp
> 
> ...


Direct link to RSA 266:1: http://www.gencourt.state.nh.us/rsa/html/xxi/266/266-1.htm


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## fishguts (Dec 19, 2008)

Darxus said:


> Ah, thanks. Laying flat in bed with just my head propped up while using a laptop for hours makes my throat sore from the angle. I think sitting up this much wouldn't be a problem. Definitely worth considering, and testing.



You'll just have to experiment to see what's comfortable for you. As illustrated, you'll be just looking over your knees - that's pretty laid back for sure. Would be a neat low profile, but an old bugger like me is wondering how the heck you'd get out of that thing! ha ha Person in the back seat better be real skinny!

But I do like it - sleek, cool looking. 

The plexi windshield will hold up fine (unless you race on a dirt track). Plexi usually gets scratched when people clean it with paper towels. A soft cloth is what to use. Most of my experience with it is with boats, so that's a different world, but look at all the motorcycles out there with plexi fairings and windshields. It's also easy to form. I can tell you how sometime if you are interested.


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## toddshotrods (Feb 10, 2009)

Darxus said:


> Ah, thanks. Laying flat in bed with just my head propped up while using a laptop for hours makes my throat sore from the angle. I think sitting up this much wouldn't be a problem. Definitely worth considering, and testing.


Put a long rod through the driver's head indicating his line of sight. Right now he's looking at the stars - nice view but I'd be beating him in his bubble head if I was her, telling him to watch the road!  Now rotate the head and rod, from the shoulder/chin area, until the line of sight touches the surface at a point about the length of the entire vehicle in front of it. That will give you an indication of how much you'll have to crank your dome forward to see where you're going. You;ll also see how much you're stretching your neck to see forward.

If you try doing a real-life mock-up you have to be reasonably accurate with the measurements. Get some boards from the local hardware/home improvement store and duplicate what's in the model as closely as possible. You'll want something solid like wood, so it won't give and allow you to subconsciously shift it into a more comfortable position. Put something small (like a pop can) on the floor a vehicle length in front of the nose of your vehicle and see how long you can stare at it before fatigue sets in. What you want to be conscious of is mental fatigue, more than if you think you're comfortable. If you're uncomfortable, you'll stop and get out. Not very much fun though, if it happens every fifteen minutes. On the other hand, if you begin to experience serious mental fatigue, you start endangering yourself and others on the road.

I have neck issues. If I sat in that car for five minutes I would have a migraine, but I have been on motorcycles with low clip-on bars for hours with no problems. It's all relative...


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## Darxus (May 10, 2010)

Join me on IRC (Internet Relay Chat) in ##ecars on irc.freenode.net (no typo, two #'s).
If you're not familiar, this protocol is older than the web, and used by lots of people. Instructions are here: http://freenode.net/using_the_network.shtml
It works best if you can stay connected 24/7.


I just noticed that the world record for an electric vehicle is 555.6 km (345 miles) in a Daihatsu Mira Van with no apparent interest in aerodynamics. Anybody want to sponsor me on a battery pack? Seriously. I'd get moving much quicker.


Looks like I'll be building a mock-up out of 4'x8'x7/16" chip board for $15 each, the cheapest stuff I found that seemed sturdy enough. Should I go with the cheap option of only getting one, cut down the middle lengthwise, and holding it together with scraps in the barn that my house came with, or at least $80 (including truck rental) to start a more extensive mock-up? 

I'm thinking the one board will give me all I need, since I have a detailed and easily manipulated computer model, and I just need to make sure the space is tolerably large enough for humans.


Looked through New Hampshire law, and what looked applicable of federal law. No major problems, for which I am very thankful. No problems from the state. The two annoyances are, of course, from the DOT. 

All glass (and acrylic / plexy / etc., collectively called "glazing") is expensive due to extensive safety laws, specified in an ANSI document that I have to PAY ($60) to be able to read: ANSI/SAE Z26.1-1996. Flat glass is expensive. I expect curved glass to be silly expensive. This seems to me to be a significant barrier to development. I really don't see what laws need to apply to an acrylic windshield, other than "Visibility must be at least Z." And possibly "Won't break if you drop an N pound rigid object on a section X"xY"".

Looks like being classified as a motorcycle is going to mean putting controls in the standard motorcycle places: Front brake and throttle on the right handlebar, rear brake at the right foot. I'd prefer right foot throttle and left foot brake. But I think I can deal with that one. 

But other than that, no significant change of plans. 


toddshotrods:
Yup, this is why I need to build a mockup. Humans are complicated. Thanks for the point on mental fatigue. I love the feeling of riding a motorcycle in a crouched position, and I've thought about using that, but I really can't see how I could remain comfortable without any support from the wind. My SV650 has race handlebars and foot pegs. Makes the interaction with the road much more intimate.
http://www.chaosreigns.com/gallery/Darxus_SV650_with_Woodcraft_bars_and_high_pegs.jpg.html


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## toddshotrods (Feb 10, 2009)

Darxus said:


> ...Looks like I'll be building a mock-up out of 4'x8'x7/16" chip board for $15 each, the cheapest stuff I found that seemed sturdy enough. Should I go with the cheap option of only getting one, cut down the middle lengthwise, and holding it together with scraps in the barn that my house came with, or at least $80 (including truck rental) to start a more extensive mock-up?
> 
> I'm thinking the one board will give me all I need, since I have a detailed and easily manipulated computer model, and I just need to make sure the space is tolerably large enough for humans...


That one sheet should give you enough, combined with the scraps you have, to mock up a stable seating arrangement. I would use smaller pieces that can be easily attached and relocated for other critical elements. Foam and poster board with masking tape are good too. I like using them because they're cheap. You can build mock-up motors, batteries, etc, really cheap and try different sizes, locations, configurations.

Another thing you should do is solidly box in your foot space. See how it feels when your feet absolutely cannot move outside the confinement. Likewise a couple pieces screwed on to keep your elbows and hips confined. Allow for any padding, and maybe glue some cheap upholstery foam on it to get a real sense of things.

This may sound crazy to people who are conversion oriented, but it's a crude form of how the vehicles you're converting were developed. We tend to take for granted the engineering that goes into developing personal transportation.




Darxus said:


> ...All glass (and acrylic / plexy / etc., collectively called "glazing") is expensive due to extensive safety laws, specified in an ANSI document that I have to PAY ($60) to be able to read: ANSI/SAE Z26.1-1996. Flat glass is expensive. I expect curved glass to be silly expensive. This seems to me to be a significant barrier to development. I really don't see what laws need to apply to an acrylic windshield, other than "Visibility must be at least Z." And possibly "Won't break if you drop an N pound rigid object on a section X"xY""...


They might be annoying, but they prevent some really bad things from happening. The biggest issue is how the material breaks. Tempered saftey glass shatters into thousands of little benign glass chips. They can cut but not stab and slice. Windshields are made of regular glass with a plastic film in between that keeps the glass from dislodging and becoming a weapon (other than being a nice place for your head to stop its forward momentum). Tempered glass would be horrible on the windshield because all those chips can aim straight for your eyes, open mouth, etc.

Plastic also breaks in different ways. Plexiglass, which was once common, breaks like normal glass into shards that can puncture and slice mercilessly. Lexan doesn't, and is the standard material used for racing applicatios. It really does make a huge difference what you use.

You also have to dig deep enough to see which if those requirements relate to a specialty car in your state. In Ohio, we have a LOT of freedom. They mainly check basic safety equipment. We have to have receipts for every piece that is used to build it though.


Have fun!


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## John (Sep 11, 2007)

toddshotrods said:


> If you try doing a real-life mock-up you have to be reasonably accurate with the measurements. Get some boards from the local hardware/home improvement store and duplicate what's in the model as closely as possible. You'll want something solid like wood, so it won't give and allow you to subconsciously shift it into a more comfortable position. Put something small (like a pop can) on the floor a vehicle length in front of the nose of your vehicle and see how long you can stare at it before fatigue sets in. What you want to be conscious of is mental fatigue, more than if you think you're comfortable. If you're uncomfortable, you'll stop and get out. Not very much fun though, if it happens every fifteen minutes. On the other hand, if you begin to experience serious mental fatigue, you start endangering yourself and others on the road.


Looking at your preliminary design I think your passenger will be very uncomfortable sitting in such a confined position and not being able to see past the drivers head. What happens to the driver’s control of the vehicle if the passenger lifts their knees or moves their arms as they would tend to do a lot if they are uncomfortable? The laid back position of the driver also means that their elbow joint is almost straight. What does this do for their range of movement and the forces they can comfortably generate at their hand to move the steering. How much could the handle bars move forwards while steering the machine before that hand had to let go due to range of movement issues. Can you afford to let go with hand controls? 

I would consider using a 60% laminar low drag body. The higher the percentage laminar the more the thickest section of the body moves aft. This will help with packaging and aero at the same time. Rather than using a pure body of rotation consider stretching the top half vertically for better packaging. 

For aerodynamic stability consider increasing the side area aft of the centre of gravity. Objects in motion through the air the centre of pressure will try to follow the centre of gravity. As for considering the angle of attack irrelevant consider what happens when the car encounters a cross wind or turns a corner. A 10MPH cross wind at 35MPH would cause about a 16 degree off axis wind direction besides the pointy front end could be dangerous to pedestrians. I believe the EV1 was designed to be most aerodynamic at 10 degrees off axis wind direction. 

The attached sketch is something I drew a couple of years ago. You may find it interesting.


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## Woodsmith (Jun 5, 2008)

Have a look at Project Sanderson's Flickr. You will see in the set how he went about designing the body for his HPV. It might be useful for you.

He mocked up like this.




So that he could build a body like this.


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## John (Sep 11, 2007)

It's interesting just how shrink wrapped some of those HPV's get. Some have taken to using a camera and video screen to navigate and gone 
windowless in pursuit of the ultimate slippery shape. My concept is a behemoth in comparison. One of those HPV's hit 80 MPH on just human power (1/4hp?).

The thing that really derailed the idea for me was the glass windows that would be required to get it legal in NZ. Another difficulty is windscreen wipers are mandatory and must wipe at least 70% of the screen in NZ. I'm sure glass could be made for a price. Getting it optically clear and distortion free through that tight and changing bend at the front and with its compound curvature it would be exceedingly difficult and hence prohibitively expensive. Coming up with a system to effectively wipe that screen and not disrupt the air flow (such as parking inside the A pillar) would certainly be challenging. The concept was also just a bit too in your face for me. 

Note the 60% laminar profiles that wrap the wheels and people pod and how they allow the wheel pants and pod to be fairly short at the rear without resorting to a kammback. Note how the rear passenger can look over the driver and both can lean forward to some degree. This should help make the design less claustrophobic. I wanted the design to be reasonably large in profile at least so that it had some presence on the road and other vehicles would see it.


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## Duncan (Dec 8, 2008)

Hi John
You probably already know this but if you have a "streamlined" body the drag is caused by skin friction and is proportional to "wetted" area so it makes sense to make the vehicle as small as possible 

As far as I am aware we don't need a windscreen and wipers here in NZ so long as we can either see over the screen or somehow move it out of the way when its raining
Like the old folding screens

That could give you an option to achieve the low drag when its dry


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## sunworksco (Sep 8, 2008)

You can use Ducati wheels/brakes and Kevlar belt-drive.
Here are a couple of examples of designs.
Regards,
John


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## toddshotrods (Feb 10, 2009)

I'm very intrigued by the whole monocoque construction thing now.  I'm toying with the idea of a monocoque street rod, to see just how light I can get it. What are you guys using to determine and develop the technical characteristics of the shell? How are you determining the what type of loading it can support, how the stress from the suspension attachment points transfers into the vehicle? What type of construction materials are you planning? What are the construction methods and materials for your suspension attachment points?

Just curious about how you're going about building. My new design software can do most of these analysis, but I haven't had time to do anything but install it so far. It reportedly has a moderately steep learning curve. Maybe a project like this will give me a way to explore some of its features.


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## Woodsmith (Jun 5, 2008)

I wish you would 'go for it' Todd, you could come up with something really fluid and 'sexy' looking.

An off the shelf monocoque trike shell kit would be fantastic.

You could work on the basis of a series of equally spaced 'rings' that form the cross sectional shapes of the monocoque in a sandwich contruction from front to back.
Each ring could be braced to it's neighbour with a series of thin struts to form a sort of wire frame. That can then be filled with foam and then glassed over.
Motor and suspension mounts could be built into the wireframe and secured to the section rings and braced across to spread the load.

You could market it as a flat pack.


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## toddshotrods (Feb 10, 2009)

Woodsmith said:


> I wish you would 'go for it' Todd, you could come up with something really fluid and 'sexy' looking...
> 
> An off the shelf monocoque trike shell kit would be fantastic...You could market it as a flat pack.


Geez Woody, you went straight to production!  I am just toying with the idea of a one-off concept, as an exploration into different areas of design, and of course for marketing my design services. The two issues I have with production are composites and liability. 

While I love the potential of composites, I can't stomach the thought of doing anything more than an occasional product. I guess I spent too many years scratching my skin off to enjoy it anymore. Sub-contracting the shell construction sounds expensive, and EV enthusiasts are normally _very_ cost senstive.

Product liability for a composite, monocoque, road-going, vehicle kit sounds like a recipe for lawsuits. Guy buys, builds, and enjoys his trike; then gets T-boned by a runaway Geo Metro, and doesn't make it. The wife decides to sue me too, even though the Metro driver was legally blind and didn't see the light turn red, because she was always terrified of him being out there in that little plastic bubble! A conventional chassis I can verify all day long, from 100+ years of them being used. A "plastic eggshell" (view that would likely be painted to a jury)? 

As usual though, you're thinking how I'm thinking as far as construction is concerned. We should discuss this idea further. I've already begun collecting parts...  Not sure whether to start yet another thread, or discuss in PM?

Sorry for the hi-jack Darxus. I really am interested in your plans for structural integrity, attachment points, etc; and figured the shared knowledge of others considering/experienced in monocoques could help everyone.

Without going into too much detail about my own plans, I am thinking about a couple/few wood stringers that would run longitudinally from the front suspension points to the rear. Wood because it has some inherent strength, and can be easily machined to accept metal attachment points. Thoughtfully spaced ribs, as Woody referred to, along the length and 'glass it all in with S2 cloth; and maybe some carbon fiber and/or Kevlar reinforcement in key areas.

I think I am going to work from the outside in though. Basically build a thin exterior shell, then incorporate all the structural components in from the bottom and openings. So the ribs and stringers can be cut and shaped to fit the shell. The rib cores would be foam.


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## TomA (Mar 26, 2009)

Woodsmith said:


> You could work on the basis of a series of equally spaced 'rings' that form the cross sectional shapes of the monocoque in a sandwich contruction from front to back.


In fuselage-speak these rings are called formers. They are located at and define specific cross sections of the shape, (stations,) and are then connected by stringers (boat speak) or longerons (aircraft-speak.) This is in fact how most boats and airframes were built for centuries. Still are, in many cases. Monocoque construction is different...

My construction technique will be S2 glass fiber over styrofoam, (Extruded Polystyrene or EPS,) not the beer-cooler pearl stuff, but the blue or pink 2" thick panels. It cuts nicely with a hot wire, is easily glued and epoxied, and relatively cheap. 

Urethane foam is nicer to sand and finish, but its toxic when heated with the hot wire, and it powders under vibration. Its more expensive, so I'm going with the EPS. 

An ideal build would be a single molded piece of EPS covered in composite (epoxy and glass) matrix. This isn't practical for anything short of volume production, so I'm going to piece together the monocoque with the slabs, sand to shape, glass the outer shape completely enclosed, and then cut out the access panels and holes for wheels, cockpit, etc. I am still working out whether to employ steel subframes for the suspension pickups, or just hard points on an all-composite chassis. I'm not an engineer, so it isn't an easy problem for me. Of course, it wouldn't be all that much easier for an engineer, either.

I will probably have a mix of subframe and steel hard point suspension attachment, with the shell being primarily S2 glass and Kevlar reinforcement as necessary. The problem with composite isn't strength, its the failure mode- catastrophic (shatter) when it goes. That's why I want the steel subframes. Wood is an excellent strength reinforcement material for composites. The thin longitudinal wood stringer is what gives a traditional surfboard its strength and resistance to shattering. 

Anyway, the slightly shorter answer is that calculating strengths and loads for these materials is aerospace design engineering, and well beyond even accomplished car builders. That's why composite structures tend to be so heavy, because the designer isn't Burt Rutan, and he's being conservative in the absence of any real knowledge of what the material needs are for the strength required. That's one reason why kit car bodies weigh up to 500lbs, when they could actually be under 100lbs if they were as efficient as composite aircraft in using the same materials. I'm stuck in this same box, and will be using steel and significantly more composite mass than I probably need because I just can't do the math to divine the lowest possible weight for my purposes. Not a big deal, but another real downside of using an exotic material.

Anyway, back to this former-stringer construction. I wouldn't recommend it if the idea is simply to make up the core of a stressed-skin monocoque outer shell. Making the stations and ribs of different materials, and filling in the gaps with 2-part or spray foam introduces a lot of variables into the material. I can't imagine that being particularly easy, either.

It would be much better to just use the software to make the whole thing up out of formers cut from 2" sheet. They could be stacked longitudinally and registered on a temporary (or permanent) keel fixture of some kind, sanded smooth, and then glassed into one solid thing. The interior shapes and contours of the shell (basically, the entire composite hull) can also be designed into the 2" body section former patterns, so that the complete monocoque would be built up out of the same material all at once in 2" slices. Pretty straightforward technique, really. 

In fact, there's an interesting business opportunity for someone who can produce a stack of these former patterns for such a design. With just a plotter, you could print the stations out full size (a 13' long trike like mine would need about 100 of them, and none would require bigger than 42"x60" paper,) that the customer would adhere directly onto 2" foam to hot wire out the station formers. Better yet, I would glue the former patterns to Masonite and cut that out to make a set of hot wire cutting templates that would produce tapered 2" near-net shaped body sections when a slab of foam was cut between 2 of the templates. A ton of hot wiring, some alignment, a little sanding, and you would be done. Extremely cool.

The set of templates could be rented out, or used to start a small production run of bodies. I can't think of a simpler or more elegant way to get an envelope body built up in a garage with ordinary tools and skills, or a better way to make more than one...

If anyone wants to pursue that with me, let me know. I have a design I'm working on, but I'm CAD-illiterate. I'm also a very good businessman with multiple start-up experience, a serious hot rodder, and I'm ready to work on this. If not, do it yourself anyway, make it work, and offer it as a service. I will be one of your first customers for my design if you are ready to proceed when I start building this winter. So there's the offer- build a capability and a business (and at least one really, really cool electric hot rod for yourself) with me, or do it all yourself and call me when you are ready to sell your fabrication template service product.

Just an idea...

TomA


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## Darxus (May 10, 2010)

I'm feeling demotivated by the cost of batteries. 

I need better kilowatt hour battery need estimation for my commute. 
I want to be able to get to work and back, 35 miles each way, part of which is 65mph, with some reasonable headroom. That's where I came up with a 100 mile range.

I worked out that I need 16,000 watt hours, which works out to about $6,000 in Thunder Sky batteries. I do believe that was a very pessimistic estimate, and that it's quite possible half as much would do it. I based that calculation on this car's efficiency:
http://www.evalbum.com/3202

And it probably is reasonable to expect to manage half the curb weight and a third of the frontal surface area. Not to mention entirely laminar vs. not.

The TIG welder I'm going to need to buy for this will probably be at least $2,600 (Miller Dynasty 200 SD - interested in recommendations). And I still haven't gotten an answer better than "It could be $3,500" on windows, probably ten times what I could make it for, just as safe, without the requirement for the little numbers etched on.


I'm hoping to get all my old window fans and some cardboard together to do the input end of the wind tunnel tonight. And based on the results of that, pick up hard board to do an 8'x2'x2' tunnel. Then make a drag scale out of some heavy wire, a protractor, and a small weight of some kind. And get some heavy paper to create 3D models with tape.


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## toddshotrods (Feb 10, 2009)

TomA said:


> ...I'm not an engineer, so it isn't an easy problem for me. Of course, it wouldn't be all that much easier for an engineer, either...





TomA said:


> ...I have a design I'm working on, but I'm CAD-illiterate...


I am on the CAD side of all this. My two primary business associates are also (Ph.D) engineers, so it's more a question of whether or not it's feasible to put the time/money into it for me. The beauty of doing this stuff in the 21st century is the software does most of the work. My software can determine where the major stress would be, where it will fail, etc. But again, it takes time to accurately model stuff for computer analysis...



TomA said:


> ...I'm also a very good businessman with multiple start-up experience, a serious hot rodder, and I'm ready to work on this...
> Just an idea...


It sparks my interest, but I have concerns about liability and ROI.


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## toddshotrods (Feb 10, 2009)

Darxus said:


> I'm feeling demotivated by the cost of batteries...


I feel your pain. The cost of building an EV is what made me decide to build a toy, instead of daily transportation. Competition is helping but this is still a very small scale market, so prices can only drop so far, so fast, without a substantial increase in demand.

I'm not trying to dissuade you from a dream, but have you considered a conversion or less-intensive build for your commute and working on the monocoque trike over time? Other than that, I would recommend finding ways to generate additional income so you can purchase whatever it takes to realize this dream (assuming you're not loaded ).


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## TomA (Mar 26, 2009)

toddshotrods said:


> It sparks my interest, but I have concerns about liability and ROI.


I'm not talking about selling the vehicle, _per se,_ I'm talking primarily about the design consulting product that offers to produce body construction templates for composite monocoque builders (of anything, really...) 

In either case, "liability" is a question of talking it over with an insurance agent and buying a policy. Everyone gets wrapped around this axle, and it is painfully simple. If you make a good product, you probably don't need liability insurance for the reason you might think- your liability. The actual reason you need liability insurance is that it provides a defense should you be sued. That is critically important. You don't want to have to hire and pay an attorney or defend your company or its practices. You need to be able to call your insurance company and fax them the summons, and be done with it until your participation in defending the claim is required. You therefore must have liability insurance to be in business, at least with me, anyway. Its just a cost of doing business, and a pretty modest one in my experience.

ROI is a different story. That term, strictly applied to a new venture of any kind, should really stop you from lifting a finger. If you need a monetary ROI then you have to invest in vehicles reasonably likely to produce a cash return, like property, equities and financial instruments. New businesses have a perfectly terrible track record of returning investment, and should not be started simply to make money. I'm not being smug, or overstating it. If the value you have to put into a new venture can't be risked, then don't do it.

You, or anyone, must embark on a project like this because you want to, you're able to, and achieving it would give you a cool new product that either isn't available, or solves a problem in a cool new way. What's the market for it; what are its features, price points, and how do you address the universe of people who might buy it? Those are hard questions to answer, particularly with a new service in a new technology. That's what I'm good at, but something like this isn't going to be a money-maker unless it works for the customer and can be delivered economically. Unfortunately, unless you try it you can't know whether that will be the case. Its kind of a chicken and egg problem. If you don't build it, no one will come. The risk-reward equation starts with the risk.

But let's look at ROI a little more broadly than a banker would. If the investment you're looking to see returned is really just your time, then you can look at the return beyond immediate monetary gain to see if it works for you. The fact that the endeavor is something you are interested in that produces something really cool may make project worth doing for those reasons alone. In other words, it might be a very good use of your time even without clear future profits. The project may also very likely create a value all its own to your future business- like getting you into a community, being a calling card for you, or opening other doors down the road. Those can be very substantial returns. To be sure: if you have to be sure your time investment will be returned with a certain amount of money in a given time frame, then don't pursue the project. Of course, that's how OEMs and public companies decide to do or not to do things, (and why so little of the world's true innovation is attributable to them.)

Anyway, this is pretty far off-topic, and I may well go start another one about being in business doing something that you love and changing the world, but I'm done talking about it here now. Follow up with me privately if and when you'd like to talk more about it.

TomA


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## Darxus (May 10, 2010)

toddshotrods said:


> ...have you considered a conversion or less-intensive build...


Thanks, I needed that.

My first several thoughts were "but anything else would require _more_ power."

Then I remembered lead acid.

And the same watt hours in Trojan T-105s is $1,700, and only about 3.6'x1.8'x0.6'.

Still hoping to start work on the wind tunnel tonight.


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## toddshotrods (Feb 10, 2009)

Darxus said:


> Thanks, I needed that.
> 
> My first several thoughts were "but anything else would require _more_ power."
> 
> ...


Did you do any mock-ups, even living room floor leaning against the sofa type, to see if the seating position was okay for you? Maybe with a little cutie behind you?  Just curious about how different people can tolerate/appreciate different driving conditions. Since you like the crouched race bike position like me, I am interested to know if you like the extreme recumbent position in your model as well.

I don't remember if I mentioned it - sweet bike!

Other options might require more power, but I figured the reduced cost to get them on the road may make it worth it. I usually try to turn over every stone to see how my plans look in comparison, so that's just a thought from an obsessive perfectionist. It all comes down to what your real goals are, and what best realizes them.

Any thoughts on what specific construction method you plan to use?


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## John (Sep 11, 2007)

Darxus said:


> I worked out that I need 16,000 watt hours, which works out to about $6,000 in Thunder Sky batteries. I do believe that was a very pessimistic estimate, and that it's quite possible half as much would do it. I based that calculation on this car's efficiency:
> http://www.evalbum.com/3202
> 
> And it probably is reasonable to expect to manage half the curb weight and a third of the frontal surface area. Not to mention entirely laminar vs. not.


Virtually everything that affects the efficiency of your vehicle is proportional to either its weight or aero drag. If you could get the aero drag down to 1/3 and the weight down to 1/3 you would need 1/3 the kWh and kW for similar performance and range as a rule of thumb. That would certainly drop the battery bill and battery weight by a bit.


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## Darxus (May 10, 2010)

toddshotrods said:


> Did you do any mock-ups, even living room floor leaning against the sofa type, to see if the seating position was okay for you? Maybe with a little cutie behind you?


Yup. 

Darxus: How would you feel about being in this car with me? Should I not bother to try to fit a passenger?
Zephlett: I don't see why I wouldn't 
Zephlett: I would ride your blackbird with you.
Zephlett: this doesn't seem too different.
Darxus: That's basically what I was thinking.



> Just curious about how different people can tolerate/appreciate different driving conditions. Since you like the crouched race bike position like me, I am interested to know if you like the extreme recumbent position in your model as well.


From what I know so far, I really like it.



> I don't remember if I mentioned it - sweet bike!


Thanks. I do love my toys. 



> Other options might require more power, but I figured the reduced cost to get them on the road may make it worth it. I usually try to turn over every stone to see how my plans look in comparison, so that's just a thought from an obsessive perfectionist. It all comes down to what your real goals are, and what best realizes them.


Yeah, but for "more power" I was still thinking lithium. Which would increase cost.



> Any thoughts on what specific construction method you plan to use?


English wheel (for body shaping) and TIG welding.

Nice and simple


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## toddshotrods (Feb 10, 2009)

Darxus said:


> ...From what I know so far, I really like it...


Cool. 



Darxus said:


> ...English wheel (for body shaping) and TIG welding.
> 
> Nice and simple


I would love to have all aluminum bodies on my street rods, but don't have the patience. I could get through side one, but duplicating it on side two would be pure torture (perfectionist). I would just have them made but a full race powertrain is more important to me right now. I was quoted around $50K to duplicate the parts I have on the truck now. Maybe you should go into business doing it, if you turn out to be pretty good with that wheel and welder.


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## Darxus (May 10, 2010)

Duncan said:


> If you are serious about low drag you need to look at the solar racers


I was briefly excited about this idea, but it turns out they're doing the same thing I am (dual wishbones). They're just taking advantage of the necessary dimensions of the solar panels. For this design it would entirely involve adding frontal surface area. So I think wrapping all the suspension rods in little airfoils is probably the best option. And what, it turns out, F1s are doing.

I have no frontal surface area to move around. It's currently basically just the humans, in an already silly position, and the wheels.



> If you have a shape that the flow doesn't separate from (stream-lined) then the old CD x area no longer applies


Awesome. Do you know how far you can maintain laminar flow of air according to Reynolds?



> How long were you allowing for your commute?
> The HPV record is now over 50mph - normal bikes its about 35mph


It's about an hour each way in my Accord. I'd rather not increase it much.



> light weight (50lbs) low power 50 - 150 watts
> pedal + electric
> or
> 200+ lbs, 400+ watts light weight electric+
> ...


Yup, I was actually thinking motorized bicycle similar to the land speed record bikes for a while. Then I figured if I'm adding a motor, I might as well add a back seat, then....


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## Woodsmith (Jun 5, 2008)

toddshotrods said:


> Geez Woody, you went straight to production!
> 
> As usual though, you're thinking how I'm thinking as far as construction is concerned. We should discuss this idea further. I've already begun collecting parts...  Not sure whether to start yet another thread, or discuss in PM?





TomA said:


> In fact, there's an interesting business opportunity for someone who can produce a stack of these former patterns for such a design.
> 
> If anyone wants to pursue that with me, let me know.
> 
> ...


I was only thinking out loud and look what it started!


I keep looking at reverse trike designs and thinking of getting another project on the move too. I have the back wheel and drive, just need to build forwards from there.

The light weight option is really the tempting aspect along side the look. I only want a single seater so should be even easier to build, no 'cutie' or 'honey' to worry about.

One of my students reminded me of another overdue trike.
Presenting a seminar on 70's furniture design he spoke of 70's futuristic and space age products and ideas and showed an image of the Aptera. I had to stop him and mention that the Aptera happened some 30 years after the period he was supposed to be presenting on.


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## Darxus (May 10, 2010)

toddshotrods said:


> Maybe you should go into business doing it, if you turn out to be pretty good with that wheel and welder.


I'm happy to take a down-payment from anybody on the first one now. I've been thinking it would be great fun to just keep making one and driving it until I can sell it.


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## Darxus (May 10, 2010)

Woodsmith said:


> The light weight option is really the tempting aspect along side the look. I only want a single seater so should be even easier to build, no 'cutie' or 'honey' to worry about.


Nng. Yeah. I was playing with a single seater model last night (in my desperation to reduce battery costs). Seating position = laying completely flat except with the head propped up. Batteries moved to pods on each side with air in between to reduce the distance air gets displaced.


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## sunworksco (Sep 8, 2008)

toddshotrods said:


> I'm very intrigued by the whole monocoque construction thing now.  I'm toying with the idea of a monocoque street rod, to see just how light I can get it. What are you guys using to determine and develop the technical characteristics of the shell? How are you determining the what type of loading it can support, how the stress from the suspension attachment points transfers into the vehicle? What type of construction materials are you planning? What are the construction methods and materials for your suspension attachment points?
> 
> Just curious about how you're going about building. My new design software can do most of these analysis, but I haven't had time to do anything but install it so far. It reportedly has a moderately steep learning curve. Maybe a project like this will give me a way to explore some of its features.


I'm using www.alulight.com all-aluminum foam panels.
The military is using this material in vehicles for strength and weight savings.It can be welded or epoxied together with aluminum extrusions.
The slab-sided trike is my choice.
I'm using Palatov independent suspension with front-wheel-drive.The hubs/wheels,brakes will be Ducati 1098 design.The rear suspension is Ducati 1098,too.
Regards,
John


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## John (Sep 11, 2007)

Darxus said:


> Do you know how far you can maintain laminar flow of air according to Reynolds?


I don't know according to Reynolds but my understanding is that as long as the flow is accelerating along the surface it will remain laminar which is why the flow doesn't stay laminar much past the thickest section of the shape. It is also really easy to trip the airflow and cause turbulence. Even something as seemingly benign as a piece of tape stuck to the surface across the airflow could do it. I think this is why they built the camera bikes so that they didn't have to have seams for glazing and could tuck the driver down into a position where he couldn't see past himself. Seams for glazing and hatches should probably follow the flow lines until after the flow ceases to be laminar as much as possible.

Notice in my concept I placed the font axle at the drivers knee joint. This would allow structure such as a box beam of some depth to be run across the vehicle to pick up the front suspension on either side. If I were trying to build some sort of all wheel drive performance variant there might be enough room to run a drive of some sort through here. The structural shell would finish at the partition behind the passenger with a lightweight sub frame and light composite shell fleshing out the rear section of the vehicle.

Darxus what do you know about dynamics of trikes? For instance do you know the optimum place for the CG?


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## TomA (Mar 26, 2009)

John said:


> For instance do you know the optimum place for the CG?


According to _Walter Korff_, _RQ Riley, Paul Van Valkenburgh_ and others, for a reverse trike, the longitudinal CG is optimal at 1/3 of the distance from the front axle center line to the tail wheel axle. That equates to 1/3 of the total weight being on each wheel. Its actually a pretty simple and intuitive guideline. That location gives the mass of the trike the greatest resistance to tipping over sideways without flipping forward under braking. The farther your CG gets aft of that spot, the lower the CG has to go to in the chassis to maintain resistance to tipping over. 

Darxus' current (and frankly most other) designs look pretty tail-heavy by that standard...

TomA


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## Darxus (May 10, 2010)

Started the wind tunnel:


















Planning to attach 8'x2'x2' of hardboard to this. 

The plastic bag is just to show wind.


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## John (Sep 11, 2007)

TomA said:


> According to _Walter Korff_, _RQ Riley, Paul Van Valkenburgh_ and others, for a reverse trike, the longitudinal CG is optimal at 1/3 of the distance from the front axle center line to the tail wheel axle. That equates to 1/3 of the total weight being on each wheel. Its actually a pretty simple and intuitive guideline. That location gives the mass of the trike the greatest resistance to tipping over sideways without flipping forward under braking. The farther your CG gets aft of that spot, the lower the CG has to go to in the chassis to maintain resistance to tipping over.
> 
> Darxus' current (and frankly most other) designs look pretty tail-heavy by that standard...


Yes since all the vehicles roll resistance comes from the front axle (the single rear wheel cannot provide any roll resistance) the closer the CG to the front axle the better the roll resistance. Beyond the point where lateral skidding would occur more roll over resistance is unnecessary. The coefficient of friction of rubber on dry tar seal is about 1.4. A lateral g of about 1.2 would be considered excellent so this is probably a good value to use. Draw a line between the contact patch of a front tyre and the rear tyre (this is your roll over hinge line). The ratio of the minimum horizontal distance to this line from the CG and its height above the road will give your roll over threshold in lateral g. Anything above about 1.2 should be safe.

As you rightly point out 1/3 back will equally load all tyres in static balance. Since the rear suspension must have a ground level roll centre this wheel will roll equal to body roll. If you adopt a ground level roll centre (such as equal length parallel A arms) for the front suspension also then they will also roll equal to body roll when cornering and consequently the same as the rear wheel. This coupled with the perfect weight distribution would give very balanced handling if you have used similar tyres on all three wheels. The temptation is to use a larger rear tyre in pursuit of a look.

Because the rear wheel provides no roll resistance there is very little in the way of torsional loads applied to the trike body. Structurally a trike could be fairly simple.

In an ultra light vehicle I favour the idea of placing the variable loads (in an EV just the occupants) at the CG more specifically putting the occupants CG on the vehicles CG particularly in plan view. This way the dynamics don't change with a change of driver.


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## Darxus (May 10, 2010)

TomA said:


> Darxus' current (and frankly most other) designs look pretty tail-heavy by that standard...


Yup. I've been aiming for 50/50 front/rear, with twice the tire in the rear. It's a good acceleration / steering balance in cars, but yes, more likely to tip with one rear wheel. But the thing is only 41" tall.

The 50/50 front/rear balance is probably more relevant to over-steering / under-steering, and having the same wheels / tires all around, with equal weight on all of them (as you described) sounds like it should do about the same. Only relevant near the limits of traction. But might as well balance the thing.

I don't know, if you only have one rear drive wheel, I could still see the 33% all around balance causing over-steer.


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## sunworksco (Sep 8, 2008)

Here are some helpful drawings.
Regards,
John


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## Darxus (May 10, 2010)

sunworksco said:


> Here are some helpful drawings.


I think with FWD with that layout you're going to want to move weight forward a lot. And use tires proportional to the weight they're supporting.

I am heavily biased in favor of RWD, but I once saw a TV show comparing two race cars that were very similar, built by the same team for two different things, one RWD, one FWD. They both worked. They just piled the weight and the tire contact patches on the front of the FWD.

Why are you going with FWD?


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## John (Sep 11, 2007)

Darxus said:


> Yup. I've been aiming for 50/50 front/rear, with twice the tire in the rear. It's a good acceleration / steering balance in cars, but yes, more likely to tip with one rear wheel. But the thing is only 41" tall.
> 
> The 50/50 front/rear balance is probably more relevant to over-steering / under-steering, and having the same wheels / tires all around, with equal weight on all of them (as you described) sounds like it should do about the same. Only relevant near the limits of traction. But might as well balance the thing.
> 
> I don't know, if you only have one rear drive wheel, I could still see the 33% all around balance causing over-steer.


There is a couple of reasons why I would rather not do some thing like this and its mostly to do with the draw backs of wide tires over narrow tires. Wide tires are more camber sensitive so as the trikes body rolls the rear tires grip will deteriorate faster than the fronts. If you adopt a ground level roll center its resistance to body roll might not be that good. My understanding is that wider tires tend to use a softer compound and consequently the coefficient of friction front to rear would be different upsetting the neutral balance. Wide tires have more trouble dealing with surface water which could cause a marked deterioration in the trikes handling in wet conditions. A 50/50 weight balance pushes the CG rearward which adversely affects aerodynamic stability. I'm not sure but I think moving the CG rearward also adversely affects the dynamic stability (something about the center of lateral slip resistance following the CG). Cars with rearward weight bias tend to exit the roadway traveling backwards when pushed too hard. Wide tires are aerodynamically poor and somewhat incongruent with the super efficient hyper aerodynamic theme.

FWD would advantageous in a 1/3,1/3,1/3 balanced trike as 2/3 of the vehicles reaction normal to the surface (RN) is generating friction at the driving wheels as opposed to 1/3 in RWD or twice the available traction. This is still superior to 50%. It would also be advantageous in an EV trike for regenerative braking. Aggressive regen would make the trike unstable in a RWD configuration and assist stability in a FWD configuration. Having heavy components forward assists with placing the center of gravity in the desired location and having the heavy components ahead of the occupants helps protect them in the event of an accident.


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## Duncan (Dec 8, 2008)

Hi Darxus

Attached flow - not laminar! you can keep the flow attached all of the way to the end of the vehicle - as soon as it detaches you get form drag
This is normally done with turbulent flow and turbulators are used to deliberately destroy the laminar flow 

Solar cars used to have separate wheels on pods - the fast ones abandoned that in favor of complete aero-bodies

The fiddly bits around the suspension had way too much drag

Don't look at F1 - their drag coefficients are ridiculously high!

The solar racer I worked on (we won the world championship (of American High Schools) twice had an S glass and foam aero-body

Top HPV's can do 50+ miles in an hour with less than 200 watts power,
That would mean 4 watthours/mile or your 100 miles on 0.4 Kwhrs

Assuming that you are not as good as that you should still be able to produce a streamlined machine able to do 10 whrs/mile needing a 1 kwhr pack, about 10 kg


I was looking at a leaning three wheeler with swinging arm suspension (like the rear of an old mini)
You need lots of wheel travel to cope with the lean


I would make the monocoque using the slices of foam described earlier and then cut into it to glass reinforcements for the suspension 

Why are you buying a MIG?
not saying its wrong but I decided to go with Oxyacetylene and bronze welding 

I am making a fun four wheeler Locost style - very inefficient!


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## Woodsmith (Jun 5, 2008)

Darxus said:


> Started the wind tunnel:
> 
> 
> 
> ...


You should really set the fans to pull air though the tunnel.
The blown air from the fans will be swirling so you will have vortices in the tunnel even with nothing inside to test so that would ruin any results even before you start.
The inlet end would be best as a series of short tubes stacked to fill the space. That would allow the air flow to be a smooth as possible coming in to the tunnel.

I remember seeing a miniture wind tunnel for school kids to test their toy cars. It was a square section perspex tube.
The inlet and outlet was carefully stacked with drinking straws to create a smooth flow and the fan was mounted outside the straws to pull the air through.

As a kid, back in the early 70's I tested my toy cars by rolling them down a ramp into a bath full of water. The density of the water exaggerated downforce and air bubbles showed where the flow detached.


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## TomA (Mar 26, 2009)

Darxus said:


> Yup. I've been aiming for 50/50 front/rear, with twice the tire in the rear. It's a good acceleration / steering balance in cars, but yes, more likely to tip with one rear wheel. But the thing is only 41" tall.
> 
> The 50/50 front/rear balance is probably more relevant to over-steering / under-steering, and having the same wheels / tires all around, with equal weight on all of them (as you described) sounds like it should do about the same. Only relevant near the limits of traction. But might as well balance the thing.
> 
> I don't know, if you only have one rear drive wheel, I could still see the 33% all around balance causing over-steer.


No, you aren't thinking correctly about this. 

Your biggest worry needs to be tipping over, not traction or handling at high lateral g loading. Moving the CG back even an apparently little bit, from 33% to 50%, dramatically increases your risk of tipping over.

See Dr. Patrick Starr's paper about designing stable 3 wheeled vehicles specifically targeted at the Solar Challenge racers. Those vehicles are in your weight class, and the theory and math is directly applicable to your design. The paper is here:

http://americansolarchallenge.org/e...0/Dr_Starr_Stability_Paper_-_Rev_20060811.pdf

Also, even though your trike is only 41" high, it doesn't have a particularly low center of gravity. Your battery pack and people would need to be much lower to the ground to make a 50/50 weight distribution sufficiently tip-resistant. See the TriHawk for a truly low CG. 

TomA


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## sunworksco (Sep 8, 2008)

I'm building a design similar to this.
Regards,
John


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## Darxus (May 10, 2010)

*Switch to lead acid*

Couldn't find a way to fit the increased bulk of the lead acid batteries in the body that I liked, so I moved them to pontoons. 

Aerodynamics geeking: People have said that if I can avoid boundary layer separation, then all that counts for wind resistance is the wetted area. That would mean that I should make the pontoons part of the body. But wouldn't it be better to have the increased surface area, if it means less vertical + horizontal air displacement due to separating the pontoons from the body?










Model I created in December 2007 with povray. Blender is so much better for this:








So not a new idea.


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## Darxus (May 10, 2010)

sunworksco said:


> You can use Ducati wheels/brakes and Kevlar belt-drive.


How are you going to attach the front wheels to the suspension? Just run a solid axle through the wheel and only support it from the inside? Do you have more info on the vehicle you included a picture of with motorcycle front tires?

I'm trying to find tires with a flat car type profile with the width of motorcycle tires. I could live with motorcycle tires. There are Ford Model T / Model A tires, but they may not be available tubeless.

Solar racing tires appear to only be available without tread, which would not be street legal. Also very very skinny.


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## Duxuk (Jul 11, 2009)

Tomorrow I take my scratch built trike to be inspected to decide whether it qualifies for a 'brand new' registration mark or a 'Q' plate. Then it's done! I wait for the number to come through the post and I can the drive. I started building in October 2008. I have a picture in the garage section of this site and some more info. on EValbum about my Kirk EV. The batteries are four in side pods attatched to the body, one under the knees and one between my feet. The handlebar steering is quite heavy. My weight is 330Kg plus me so a total at about 405Kg. I have used Peugot speedfight front wheels and axles which are only supported from the insides. I welded the axles into my homemade suspension uprights. I have a unique (but not yet patented) anti roll front suspension (essential for a three wheeler) which works very well indeed.

Good luck and go for it! The harder the battle, the sweeter the victory.

Andrew.


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## electrabishi (Mar 11, 2008)

Interesting read 
I couldn't figure out how to subscribe to it without replying.
So here it is... just watching for now 

Mike


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## sunworksco (Sep 8, 2008)

Hello Darxus,
Those are Ducati 1098 pin-drive-center-lock wheels.Palatov suspensions can build the hubs with double wish-bone suspension and front-wheel-drive.
With an ev weighing less than 800lbs. , motorcycle tires can do the job safely,providing the chassis is well balanced.A trike can be licensed as a motorcycle.
Regards,
John


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## fishguts (Dec 19, 2008)

Darxus said:


>




I like the battery pods idea. One could have a spare set of pods at home or work charged up and ready to go and with the right quick disconnects and something like a floor jack, could make swap them out quickly.


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## Darxus (May 10, 2010)

sunworksco said:


> Hello Darxus,
> Those are Ducati 1098 pin-drive-center-lock wheels.


Does anybody other than Ducati make anything like that? The larger hole through the wheel looks useful. All other motorcycle wheels I'm seeing just have a hole for a small bolt. If you removed the spacer, you could run a larger shaft through it, but then you'd have to come up with something new for the bearings.


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## John (Sep 11, 2007)

Darxus said:


> I'm trying to find tires with a flat car type profile with the width of motorcycle tires. I could live with motorcycle tires. There are Ford Model T / Model A tires, but they may not be available tubeless.


Would 125R15's be too wide?


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## electrabishi (Mar 11, 2008)

Darxus said:


> I'm trying to find tires with a flat car type profile with the width of motorcycle tires. I could live with motorcycle tires. There are Ford Model T / Model A tires, but they may not be available tubeless.



Maybe some drag racing tires mad for the front. Many come on 4" rims. Don't know if they come any smaller, but would be a place to start looking.

Mike


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## Darxus (May 10, 2010)

sunworksco said:


> Hello Darxus,
> Those are Ducati 1098 pin-drive-center-lock wheels.Palatov suspensions can build the hubs with double wish-bone suspension and front-wheel-drive.


It eventually sunk in that what's useful about these is not the big hole in the middle, but that they're designed to be supported by a single swingarm - from only one side. 

Ducati still sounds too expensive and fragile to me, but there are a bunch of other bikes that have used a single swingarm somewhere, and one that even used a front single swingarm, the Yamaha GTS 1000. And dual rear swingarms, which is also what I want, so I could use matching wheels / tires all around, which would be cute. Expensive though, all these single swingarm wheels seem to be around $800. 

The folks in #motorcycles on EFNet helped me establish that wheels / tires as thin as I'd like really don't exist in designs for cars, other than the Ford Model A / T stuff. (And reminded me which bike had the front single swingarm.)

sunworksco: I'm still curious why you picked front wheel drive.









_Much_ higher quality here: http://www.eternalmachinery.com/ecar/vid2.html
(450 frames (30fps) at 1600x800)


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## Darxus (May 10, 2010)

*Todo*

I've been working on a todo list. I'd appreciate you pointing out things that need to be added. The stuff I dread most is picking all the specific parts - preferably from an existing common vehicle, or fabricated if necessary.


Modelling
Pontoon attachment 
Brakes 
Steering 
Mirrors 
Pedals 
Calculate CG, tip angle 
Motor mounts 
Suspension mounts 
Controller and charger mounts 
Seats 
Trailer hitch (for grocery shopping) 

Prototyping
Build mockup of car to test fit people 
Finish wind tunnel 
Test various shapes in wind tunnel, including angles accounting for cross wind (for barrier layer separation) 

Parts decisions
Pick brakes 
Pick wheels, tires 
Pick headlights and blinkers 
Pick shocks / springs 
Calculate gear ratio 
Pick suspension parts, steering, gears, chain / belt 
Windshield 

Fabrication
Try tig welding 
Buy tig welder 
Learn to weld 
Make English wheel 
Practice English wheel 
Build car


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## Darxus (May 10, 2010)

I have really been appreciating the comments, sorry I haven't been very good at keeping up with responses. Not going to get to them all now either.




John said:


> Looking at your preliminary design I think your passenger will be very uncomfortable sitting in such a confined position and not being able to see past the drivers head.


My confidence that the seating position will work is based on experience with motorcycles. Hundreds of miles in a day, that close to my girlfriend. She feels the same. 



John said:


> The laid back position of the driver also means that their elbow joint is almost straight.


The steering needs to be moved back.



John said:


> I would consider using a 60% laminar low drag body.


That 60% low drag body looks good for wheel pants, but I'm having difficulty believing it would be more useful for the body. Why would "60% laminar" be better than keeping the flow as smooth as possible for the length of the car?



John said:


> Rather than using a pure body of rotation consider stretching the top half vertically for better packaging.


I haven't been sticking to a purely round body. In fact it's mostly been more square in cross section.



John said:


> For aerodynamic stability consider increasing the side area aft of the centre of gravity. Objects in motion through the air the centre of pressure will try to follow the centre of gravity.


Makes sense, thanks. I suspect this is a problem with many bullet designs, and the biggest reason they end up destabilizing.



John said:


> As for considering the angle of attack irrelevant consider what happens when the car encounters a cross wind or turns a corner. A 10MPH cross wind at 35MPH would cause about a 16 degree off axis wind direction besides the pointy front end could be dangerous to pedestrians. I believe the EV1 was designed to be most aerodynamic at 10 degrees off axis wind direction.


Excellent point, thank you very much. The possibility of boundary layer separation due to that point interacting badly with 10 degree off axis wind is... important. I'll definitely have to play with that when I get to wind tunnel stuff.




toddshotrods said:


> Sorry for the hi-jack Darxus. I really am interested in your plans for structural integrity, attachment points, etc; and figured the shared knowledge of others considering/experienced in monocoques could help everyone.


Not at all, you're well within my interests.

You folks sure make fiberglass sound tempting. Particularly the lack of a need for a $2,600 welder. I wonder if I should prototype with it. Options for hardpoints are kind of sexier.




TomA said:


> They could be stacked longitudinally and registered on a temporary (or permanent) keel fixture of some kind, sanded smooth, and then glassed into one solid thing.


Sexy.




TomA said:


> Anyway, this is pretty far off-topic, and I may well go start another one about being in business doing something that you love and changing the world, but I'm done talking about it here now.


Plenty on topic for me.




sunworksco said:


> I'm using www.alulight.com all-aluminum foam panels.


Aluminum foam sounds FUN. What's the cost like?



sunworksco said:


> I'm using Palatov independent suspension with front-wheel-drive.


Neat! I didn't recognize the name Palatov as the DP1 car guy immediately, and I guess I didn't realize he was actually selling stuff. Thanks. That four years (DP1) seemed like a few eternities. 




Duncan said:


> Attached flow - not laminar!


Right!



Duncan said:


> you can keep the flow attached all of the way to the end of the vehicle....


Excellent.



Duncan said:


> This is normally done with turbulent flow and turbulators are used to deliberately destroy the laminar flow


Scary.



Duncan said:


> Don't look at F1 - their drag coefficients are ridiculously high!


Good to know, thanks.



Duncan said:


> Why are you buying a MIG?
> not saying its wrong but I decided to go with Oxyacetylene and bronze welding


Because... I thought that was the right way to weld aluminum sheet? Hmm. Sure would be nice to have a much cheaper acceptable method. How much does the gas cost?

This... could be exciting.



> I am making a fun four wheeler Locost style - very inefficient!


I approve. I have also felt the influence (2007): 








More: http://www.eternalmachinery.com/seven/
Seating position is aerodynamically inconvenient.
Tow hooks are so sexy.




electrabishi said:


> Maybe some drag racing tires mad for the front. Many come on 4" rims.


Not street legal.


Cute!


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## Darxus (May 10, 2010)

Duncan said:


> Why are you buying a MIG?
> not saying its wrong but I decided to go with Oxyacetylene and bronze welding


Yeah, looks like oxyacetylene won't do aluminum, because of contaminants?
What's the relevance of bronze?

Oh, and TIG, not MIG.


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## John (Sep 11, 2007)

Darxus said:


> That 60% low drag body looks good for wheel pants, but I'm having difficulty believing it would be more useful for the body. Why would "60% laminar" be better than keeping the flow as smooth as possible for the length of the car?


Your dominant type of aero drag as others have pointed out is skin friction drag in a fully streamlined shape (with a minor portion of drag being form drag). There are two ways of reducing this type of drag. 1) Reducing the wetted area by basically making the design as small as possible and 2) keeping the airflow laminar over as much of the shape as possible. While it is true that turbulators are used to keep air flow attached in some instances it is usually where the departure angle is so steep that flow separation is inevitable without them. They are used to mix the boundary layer with higher energy air further away from the surface reenergising the boundary layer and preventing it from stalling for longer. If your shape is a low drag body with shallow departure angles you shouldn't need them. They would only wind up increasing your drag. If you want to see a high laminar flow shape Google "virtual rush" for an enclosed bike. That said it probably isn't feasible to maintain laminar flow over much of such a vehicle as your proposing so its value for reducing your drag is dubious. 

I like the high laminar bodies because the fattest section is well rearward in the shape and this nicely correlates to the widest part of me when I'm sitting inside the shape which is probably my shoulders or elbows i.e. also well rearward when sitting low. This gives some hope of reducing aero drag while having the largest internal volumes where they are needed.


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## fishguts (Dec 19, 2008)

I used a Honda Goldwing swing arm. They're available cheap on Ebay because shops/dealers take them off new bikes they then convert to trikes. I paid $225 for mine brand new, then sold the wheel and tire that came with it for $180. I set mine up with a fat rear tire which you wouldn't want. The gear ratio is 2.75.


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## Duncan (Dec 8, 2008)

Hi Darxus

Bronze welding (brazing is different again) is using a bronze alloy filler that melts at a lower temperature than the mild steel tubes I am using

The reason I am going this way is that it is more forgiving

Higher strength materials tend to require everything to be just right or the resultant joint is weaker than the bronze welded joint 


http://7faq.com/owbase/ow.asp?NotesOnWelding


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## toddshotrods (Feb 10, 2009)

Darxus said:


> Yeah, looks like oxyacetylene won't do aluminum, because of contaminants?
> What's the relevance of bronze?
> 
> Oh, and TIG, not MIG.


Aluminum *can* be gas welded. I tried it using it to to tack some parts that had to go out for TIG welding. I'll admit I lost my nerve because the parts had way too much time in them at that point to risk losing them. I meant to go back and try it on some scrap metal, but never did.

Aluminum is different because there's a narrow window between when it begins to puddle and when it hits the floor in a molten puddle!  There is a special flux made for gas welding aluminum. You heat the aluminum rod and dip it in the liquid flux, then weld when it sets up. I think the flux was a powder that you mix with water. Someone probably makes rods already coated now, but that is the old school way.

The main thing, regardless of what type of welding you use on aluminum is getting it clean. I scrub the parts with acetone and a clean stainless steel brush. The guy who used to TIG weld my aluminum stuff could actually tell how well, and how recently, it had been cleaned as soon as he started welding. It's recommended to stop and brush it every so often, because the oxygen in the air begins to contaminate it again as soon as you stop cleaning.


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## Darxus (May 10, 2010)

I've been learning a lot about the details of double wishbone suspension. Lots of stuff going on in there.

For the front I want to use the cheapest motorcycle wheels designed for a single sided swingarm with a symmetrical spoke pattern. Right now that's looking about like Ducati 1098 race takeoffs (factory stuff replaced with more racey stuff).

So the model includes rough models of those Ducati wheels and tires, spindles (buy common bolts / nuts), brake rotors (buy standard motorcycle), hubs (weld sheet steel), uprights (weld sheet steel), heim / rose / joints (buy). I didn't actually model the bearing yet, because it's just a cylinder that slides in the middle of all that. I figure I'll use some random basic car wheel bearing. 

I'm curious if it'll need a sway / anti-roll bar. If it does, I'm planning to do that at the rockers / bell cranks that connect the tie rods to the coil-over shocks inside the body.

A lot of this process has been finding useful pictures on the internet to show what I'm trying to figure out. I should put those together.

A lot of it has come out of Formula SAE, which seems to involve the most active design and fabrication of this stuff anywhere near a DIY level.


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## Duxuk (Jul 11, 2009)

Don't build a reverse trike without a sway bar or anti roll bar. I have built ICE trikes since 2001 and found that as weight increased body roll became a problem. I currently have a Honda Silverwing (FES600) powered trike. I know the motor weight is high and at the wrong end but the sway bar transformed the handling. It keeps the inside front wheel on the ground almost all the time! I still would never drive it as hard as a four wheeler but then again I didn't have your design freedom since the engine choice dictated a lot. I am just waiting for the licence plate for my new EV trike. (See Kirk EV aka. Sparky on EVAlbums) The c of g is low and the wheel weights without driver are 119Kg rear with the fronts at 105Kg each. I have invented an anti roll front suspension system for the EV. It cleverly links the two sides in a way which could be varied "in flight" to adjust roll resistance dependant on speed or individual corners. I know you can do this with adjustable anti roll bars but my system is better! Can't wait to be driving after 18 months of building I'll post some data on performance, range and handling when I have it in the next week or two.

Andrew


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## Darxus (May 10, 2010)

Duxuk said:


> Don't build a reverse trike without a sway bar or anti roll bar.


Now that I think about it, it makes a lot of sense that a trike would be much more in need of an anti-roll bar than a 4 wheeled vehicle with otherwise identical properties, because it only has one axle to keep it upright. I'll work on that "pushrod activated inboard suspension" then.

I'm certainly curious to hear about your invention. Is that something you can't talk about yet? 



Duxuk said:


> I am just waiting for the licence plate for my new EV trike. (See Kirk EV aka. Sparky on EVAlbums)


So your new trike passed inspection? Congratulations. I look forward to hearing how it works.


Reading about the SUB G1 has been useful, particularly because they're using the same Ducati wheel face in the same basic layout, and they provide a lot of detail. Although it may not end up affecting my design at all, it's nice to see how somebody else did it.


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## Darxus (May 10, 2010)

sunworksco said:


> You can use Ducati wheels/brakes and Kevlar belt-drive.


The cabincar.jpg image you attached is photoshopped, using the wheels from this photo: http://www.sub3wheeler.com/ (I'm not saying that you ever claimed otherwise.)



sunworksco said:


> The trike will be so light that it can use motorcycle tires.The Sub-1 does this with zero problems and weighs more.The Sub-1 tires are narrower as well.


(Quoted from locostusa.com.)

You seem to have implied that motorcycle wheels will work because the Sub-1 used motorcycle wheels. I just wanted to point out that they didn't, they fabricated custom wheels that use the same wheel face / mounting bits as Ducatis.

I'm not saying it won't work. I'm still planning to use Ducati wheels but I am now less confident it'll work than you had made me. Please do keep me up to date on how yours ends up handling side loads (high g turns).

I should email the Sub-1 folks and ask about pricing on some of those parts.


----------



## Darxus (May 10, 2010)

ATV wheels / tires / uprights / wishbones might be useful.


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## Darxus (May 10, 2010)

145/65-15 Smart Car wheels are looking good for the fronts. A little skinnier than the Ducatis, a couple inches shorter, and much wider contact patches. And designed to support side loads. 

Specifically what was at least on the FourTwo from 2004 to 2006. 
I'm having difficulty finding out if anything other than the wheel would be useful (uprights, brakes, bearings). Going to have to look for one to crawl under at work.


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## John (Sep 11, 2007)

This is what I was considering. http://store.cokertire.com/125r15-firestone-f560-blackwall-tire.html. 3/4" narrower than than the smart car tyre.


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## TomA (Mar 26, 2009)

John said:


> This is what I was considering. http://store.cokertire.com/125r15-firestone-f560-blackwall-tire.html. 3/4" narrower than than the smart car tyre.


I like that tire, especially on a Weld 15 x 3.5 inch Weld Drag Star Wheel:

http://www.summitracing.com/parts/WLD-90-54340/

These wheels are supposedly about 10 lbs each.

You could also get classic Centerlines, and there are two sets on ebay right now that are astoundingly cheap:

http://cgi.ebay.com/ebaymotors/CENT...iewItem&pt=Race_Car_Parts&hash=item3a5b78f2dc

http://cgi.ebay.com/ebaymotors/CENT...iewItem&pt=Race_Car_Parts&hash=item3a5b79038d

This is no doubt because the bolt pattern on both sets is obscure, but so what, they can be drilled to about anything. Very light weight, and strong.

TomA


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## Darxus (May 10, 2010)

John said:


> This is what I was considering. http://store.cokertire.com/125r15-firestone-f560-blackwall-tire.html. 3/4" narrower than than the smart car tyre.


That does look nice. When I was looking at similar tires before I was scared away by how many required innertubes (I realize this doesn't). 

And I think I prefer the Low Rolling Resistance tires used on smart cars over tires designed for classic cars. Continental ContiEcoContact EP. And it would be great if the hub / hub carrier / bearing are useful.


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## TomA (Mar 26, 2009)

Rolling resistance is just one piece of the puzzle. 

Any car tire you specify is going to be hugely overdimensioned for your vehicle. That's why I'm using scooter and motorcycle tires for a 400lb vehicle- they are in the design weight class for my purpose.

I don't think there's going to be a practical difference due to rolling resistance between these tires. At high pressures and lightly loaded, The more significant differences are going to be from section width (and the resulting aero effects, as they are out there in the airstream,) and from mass, which will be quite significant on such a lightweight vehicle.

Those car tires are going to be _heavy_, and their inertial properties are going to cost you everywhere except coasting. You might want to contact the guy who built the HyperRocket:

http://ecomodder.com/blog/hyperrocket-125-mpg-100-mph-3wheel-motorcycle/

He had two wheel/tire packages- motorcycle and car components. The motorcycle package was about 20% more efficient. He might have some great info for you about hubs and bearings, too.

I suspect something here I'm just going to point out: This vehicle isn't going to be very sporty, and you probably shouldn't build it if you want to go canyon carving, especially with a passenger. Build a Locost if that's what you want. I don't think any super lightweight trike is going to offer very much road-holding performance, and it will be a dangerous thing to play around with if that is the aim. If you roll it over or hit something, your crashworthiness is about bicycle-quality. 

Don't get me wrong, this class of vehicle is fascinating and really fun- I'm building one myself, just don't ask too much of it. High cornering performance is the very hardest thing to achieve in a trike. You've got a pretty full plate on this build with electric power, composites, scratchbuilt suspension, welded aluminum monocoque, etc.  I wouldn't put autocross or even rally handling very high on your list of objectives.

Just a thought,

TomA


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## Darxus (May 10, 2010)

TomA said:


> Any car tire you specify is going to be hugely overdimensioned for your vehicle. That's why I'm using scooter and motorcycle tires for a 400lb vehicle- they are in the design weight class for my purpose.


I'm currently looking at 756 pounds of batteries 



TomA said:


> You might want to contact the guy who built the HyperRocket:
> 
> http://ecomodder.com/blog/hyperrocket-125-mpg-100-mph-3wheel-motorcycle/
> 
> He had two wheel/tire packages- motorcycle and car components. The motorcycle package was about 20% more efficient. He might have some great info for you about hubs and bearings, too.


Thanks a lot for that link. I'd love to pick that guy's brain. Unfortunately he seems to have stopped responding a while ago.



TomA said:


> I suspect something here I'm just going to point out: This vehicle isn't going to be very sporty, and you probably shouldn't build it if you want to go canyon carving, especially with a passenger. Build a Locost if that's what you want.


I realize that, thanks. I've considered a locost in the past. I'm guessing your suspicion may have been due primarily to my mention of contact patches. They're not a huge concern for me, I'm much more concerned about the Ducati wheels handling side loading. As far as contact patches I was primarily considering reduced tendancy of that ~800 pounds of batteries sliding sideways off the road.

Actually I think if I switched to lithium batteries, used fat tires, and dropped the clearance from 6-7" down to 2-3" it would be pretty sporty. 

Oh, and I already have three entirely acceptable canyon carving vehicles 



TomA said:


> You've got a pretty full plate on this build with electric power, composites, scratchbuilt suspension, welded aluminum monocoque, etc. I wouldn't put autocross or even rally handling very high on your list of objectives.


Indeed. Wait, no composites. Well, maybe the front wheel pants.


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## Darxus (May 10, 2010)

*Smart Car parts*

Smart Fortwo front axle:









From the technical manual: http://scp-parts.com/pdf/2008fortwotech.pdf

The knuckle / hub carrier / upright (can I get some freaking consistency?) doesn't look good, but I still have hopes for the hub and bearing, and maybe the brakes.

I think the MacPherson strut upright could be reasonably converted to double wishbone, but I don't like how much it protrudes from the wheel (for aerodynamics).


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## Darxus (May 10, 2010)

Impressively extensive reverse trike gallery: http://s171.photobucket.com/albums/u308/SRX660/Trikes/


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## TomA (Mar 26, 2009)

Darxus said:


> I'm currently looking at 756 pounds of batteries


Hmm. I forgot you are still serious about that. 

Y'know, that's really kind of a drop dead problem. Your sidepods are only going to hold that much weight if they are carbon or kevlar composite, or steel reinforced. Hanging both of them on your aluminum monocoque is going to stress it so much that you're going to need some serious analysis to figure out where to put ribs, formers and braces to hold this whole thing together. Just the attachment detail of tying those 400lb side pods to the aluminum shell is a major engineering challenge...

Your GVW with 750lbs of lead could be 1500lbs-1750lbs. That's the same or more than a whole lot of much easier things to make, like a stretched Formula V or Formula Ford chassis, a Locost, even a Lotus Europa or Saab Sonett.

I suggest you revisit the battery issue and come to your senses. Lead is dead. You can't directly compare kWh ratings from Lithium to Lead chemistries because of Peukerts effects, but you should be able to replace that dozen T105 lump with Lithium and save 400lbs at about the same usable range. Regardless, I really think 750lbs of _any _batteries is going to render your project unworkable, or at least compromise it irreparably. I think for the sake of saving a few thousand dollars in up-front battery cost you are really heaping trouble on your chassis. Notice I said "up-front" cost, because its pretty likely Lithium is the same cost or even cheaper long-term than lead.

Prove me wrong, but add it all up first. What is your trike really going to weigh? 

TomA


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## toddshotrods (Feb 10, 2009)

TomA said:


> ...Y'know, that's really kind of a drop dead problem. Your sidepods are only going to hold that much weight if they are carbon or kevlar composite, or steel reinforced. Hanging both of them on your aluminum monocoque is going to stress it so much that you're going to need some serious analysis to figure out where to put ribs, formers and braces to hold this whole thing together. Just the attachment detail of tying those 400lb side pods to the aluminum shell is a major engineering challenge...TomA


Wow, I hadn't connected those two facts together, and realized that the battery weight would now be hanging off the sides of a *monocoque* chassis! Dude, you really need to think about your goals. What you have laid out here is a high-tech company or college university engineering challenge. There are just so many issues to deal with that a project of this magnitude is really more about solving technical engineering issues than it is building an EV.

Start with the monocoque itself. Most people who make aluminum body panels, outside of multi-billion dollar manufacturers, make unstressed aesthetic skins. When you start rolling and hammering any metal your are changing the physical characteristics of the metal. Most notably, you are work hardening the metal, which means it is more brittle than it was in a rolled sheet. When manufacturers develop stressed "skin" uni-body chassis this is all taken into account in engineering. Those panels have to be created in such a way that they still remain flexible for the intended lifespan of the vehicle. Without serious analysis, you're not going to know when and where that chassis will fail. I don't know if you've ever worked with aluminum but it hardens to the point of failure pretty fast (compared to steel).

That brings me to the battery pods. Even 200bs of lithium hanging off the side of the chassis is introducing a huge lever to bend whatever it attaches to. Over time that subtle bending back and forth, as you travel on public roads, will cause the aluminum to harden and eventually fracture, if it's not properly designed. The time it would take to accurately model all of that, conduct FEA, interpret the results, revise the design, FEA, interpret the results, etc, until a safe design was produced would be astronomical! I'm available for hire, by the way, if you have the budget!  I have two engineers, both with PhDs, that I work with biz-to-biz...

If it seems like I'm trying to scare you - I am!  You seem like a nice guy, with loads of creativity and ambition. I'd like to see you live long enough to realize some of it. Our streets are filled with too many large vehicles, traveling at considerable speeds, to be out there in a marginally executed vehicle. I will suggest again, either back the plan for this vehicle down to proven methods or build a more conventional EV for daily usage while you hash out the details of your dream EV.


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## TomA (Mar 26, 2009)

toddshotrods said:


> I don't know if you've ever worked with aluminum but it hardens to the point of failure pretty fast (compared to steel).


The big problem is aluminum alloys have an indefinite fatigue resistance, which means they keep getting weaker over time under stress. Steel alloys stop being weakened by back-and-forth bending stresses at about 70,000 cycles. That's a few hours on the dyno for a motor, and really not very much work at all. If your steel part can hold up to 70,000 test cycles- it is good from then on- it has a definite stress resistance. Most alloys do.

Aluminum continues to weaken and harden with cyclical stress, and ultimately fails. Always. Imagine that, its just a question of time. That's why airliners are reskinned every 6-8 years. All this was discovered when the aluminum window frames on the de Havilland Comet cracked in service, and several planes were lost with all on board in the late 1950s. The fleet was grounded until this ugly little problem with aluminum was understood. The solution was beefing the parts, regular inspections, and frequent replacement, and that continues to this day in pressurized aircraft. 

Aluminum is actually a poor structural material for that reason alone, but there are many others: It corrodes. It causes electrolysis. It peels and tears in failure. It expands and contracts a lot. It work hardens. Its hard to weld. Its one of those materials that's attractiveness is inversely proportional to how much you know about it. Aviation engineers have actually been trying to get away from it for 50 years...

TomA


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## Woodsmith (Jun 5, 2008)

Darxus said:


> Impressively extensive reverse trike gallery: http://s171.photobucket.com/albums/u308/SRX660/Trikes/


It doesn't have the 'ladies favorite' trike:












Darxus said:


> I'm currently looking at 756 pounds of batteries


Could you anchor the pods to reinforced hoops that are inside the monocoque?

If you had, say, two or three mounting points to the monocoque then inside the monocoque you could have a strong hoop at each mounting point that transfers the load from the pod on one side to the other side.

The monocoque will only need to take, mostly, vertical loads with any dynamic loads being spread around the circumference of the monocoque through the hoops.

The hoops can be, say, one over the dash position and one over the driver's head position leaving the entry/exit space clear.


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## toddshotrods (Feb 10, 2009)

Woodsmith said:


> ...Could you anchor the pods to reinforced hoops that are inside the monocoque?...


That would be my approach, and what I described for my own "monocoque" idea. It is the typial hot rod/amateur race approach, but it requires over-engineering the parts for a margin of safety. I would probably have a minimum section width of .500" for the hoops, and would most likely weld an outer band to them creating a rolled T beam. They would need to be connected with stringers of suitable thickness to create a rigid structure that doesn't transmit the forces from the bouncing (even if imperceptibly) battery pods directly into the monocoque skin. The pod isn't going to just pull directly down on the hoop, it will also attempt to twist it as the chassis experiences variations in pitch over road surfaces.

Basically, at that point your are at the beginning of a space frame design - which I think would be more suitable for this project. A properly designed space frame could carry those pods, but it comes with a weight penalty.

That's my point. All of the proposed goals for this project, considered together, are a serious engineering challenge. Each could probably be done safely, individually, on a project but in combination they can easily spell disaster. I love aluminum, even with its shortcomings, but you'll notice that the Inhaler's chassis is steel...

When we accidentally put a little nick in my rear motor mount, that needed to be welded up, we took it to an aluminum welding specialist who knew how to properly heat treat it and weld it. That was to respect and preserve the characteristics of the billet I purchased. That was the recommendation of the machinist, who is one of the (PhD) engineers I mentioned. Thats was on an already over-engineered, and very thick, part.


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## TomA (Mar 26, 2009)

Woodsmith said:


> Could you anchor the pods to reinforced hoops that are inside the monocoque?
> 
> If you had, say, two or three mounting points to the monocoque then inside the monocoque you could have a strong hoop at each mounting point that transfers the load from the pod on one side to the other side.
> 
> ...


Sadly, it doesn't work that way. Monocoques handle all the forces in all directions within the skin. Disrupting that leads to problems. Reinforcing a stressed-skin design isn't as simple as making hoops to accept the pylon mounting bolts. The "strong hoops" are the beginnings of a subfame, which is fine, but then you need to engineer (not guess about) how much load the skin is taking versus the subframe. Those hoops are going to need to be tied together. Now you have a tube space frame chassis. The skin will be fine, but it isn't going to do very much. You probably also have a 1500-1700 lb vehicle at this point, and it will have to be considerably larger to get two people inside that frame.

Engineering challenges like this are interesting and relatively easy to work out on screen (except for someone like me..) When you start cutting and fitting materials and trying new techniques, though, and then putting it in a jig and really loading it up to see what you've done, it gets far, far harder.

No worries, as I said long ago: everyone should build what they want. This particular project is, though, in the stratosphere of difficulty...

TomA


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## Duxuk (Jul 11, 2009)

Your going to end up making my trike! I used about 40Kg of steel box section to build a ladder/spaceframe chassis which is simply panelled in non stressed aluminium of 1.2mm guage. The all up weight therefore stays low. I have 6* 25.2Kg LA batteries. Two in each side pod, one under my knees and one between my feet. Total weight is 330Kg for a 72v 110Ah system. My first EV design, which I decided not to build, was an aluminium monocoque. I never realy resolved the difficulties of attatching the rear swinging arm. I intended to use aluminium box section across the front to spread the load and act as brackets for the wishbones. I saw this on the no longer available "Robin Hood Lightweight", which was my origional inpiration to build without a chassis.
I drove half a mile tonight. (I'm just waiting for my registration number). I checked the temperature of the motor terminals. It rose from 19 to 29 celcius on the first run and peaked a 33 celcius on the second. Max. speed was 23mph but much of the run is acceleration. I don't know what to expect on a longer run. I notice the battery voltage drops by about 4 volts when I set off and do a rapid acceleration.

Sorry to drone on about my own vehicle but I'm dreaming of my first proper drives after a long build. Can anyone reccomend a narcotic to take my mind off the wait?

Andrew.


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## toddshotrods (Feb 10, 2009)

TomA said:


> ...Engineering challenges like this are interesting and relatively easy to work out on screen (except for someone like me..) When you start cutting and fitting materials and trying new techniques, though, and then putting it in a jig and really loading it up to see what you've done, it gets far, far harder.


The best bet for the combined goals, as stated, it it to first invest in some really good software with FEA capabilities, and spend more time learing that software than actually trying to build. He could then model his ideas, run an analysis, and see what the results would be. Once he modeled the main monocoque chassis attaching a 200-400 pound pod to it, with different methods and seeing where the stress and resultant failures, would be relatively simple to do. Advanced engineering is a mouse click away in the 21st century.

Darxus it's not that you're project is impossible, it's just:


TomA said:


> ... in the stratosphere of difficulty...
> 
> TomA


 
It's very intriguing though, and if approached and executed correctly could be an incredible journey. You have to decide whether you want a cool EV or to solve major engineering challenges. That's why I said it's something a university would attempt. The goals you laid out are more about engineering than EVs or even vehicles for that matter.

You can just imagine a bunch of engineering students discussing physics and metallurgy, pouring through papers, and conducting a mind-numbing amount of tests to prove their hypothesis.


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## toddshotrods (Feb 10, 2009)

Duxuk said:


> ...Can anyone reccomend a narcotic to take my mind off the wait?
> 
> Andrew.


They're called women.


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## Duxuk (Jul 11, 2009)

Toddshotrods-"women" is a plural and goes right against my monogamous instincts. Think I'll just try my luck with Mrs. Kirk tonight. I WON'T be posting the result.


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## toddshotrods (Feb 10, 2009)

Duxuk said:


> Toddshotrods-"women" is a plural and goes right against my monogamous instincts. Think I'll just try my luck with Mrs. Kirk tonight. I WON'T be posting the result.


If I had said barbiturates (plural) would you have taken that as a suggestion to try multiple versions at once too!  Have fun!


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## Darxus (May 10, 2010)

Duxuk said:


> Toddshotrods-"women" is a plural and goes right against my monogamous instincts. Think I'll just try my luck with Mrs. Kirk tonight. I WON'T be posting the result.


Monogamy is so weird.


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## Woodsmith (Jun 5, 2008)

What are these women you speak of? I don't think have sufficient recent data to comprehend their impact on DIY EV development.


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## Darxus (May 10, 2010)

I think I decided to drop the passenger seat for my first attempt.



John said:


> Because the rear wheel provides no roll resistance there is very little in the way of torsional loads applied to the trike body. Structurally a trike could be fairly simple.


And take advantage of that. What do you think, a 2x4 for a frame? 

Also, the HyperRocket has about half the CD of a typical car, so I think I could drop the energy requirement to half for the two seater, and less for a single seater. I realize that's a massive oversimplification.


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## toddshotrods (Feb 10, 2009)

Woodsmith said:


> ...to comprehend their impact on DIY EV development...


Comparable to putting a resistor in an electrical line. How much comes out of the other end depends on the value of the resistor. 



Darxus said:


> I think I decided to drop the passenger seat for my first attempt...


In his case you can judge the impact by how many black eyes and broken bones he has after dropping that seat. 



Darxus said:


> Monogamy is so weird.


I've been squarely on both sides of the coin, and I can tell you without blinking an eye - monogamy is better. I'm on my second divorce, three years out of a great marriage, and I have no interest in returning to my former (before marriage life). There's something special that develops between the right two people when they are faithful to each other. If you're wondering why I got divorced if my marriage was so great, we just grew apart. We're still best friends, and that relationship wouldn't have been possible if one of us had violated that trust.

Right now I just don't have a lot of interest in romance. Maybe after I accomplish some of my goals...


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## Darxus (May 10, 2010)

toddshotrods said:


> There's something special that develops between the right two people when they are faithful to each other....
> We're still best friends, and that relationship wouldn't have been possible if one of us had violated that trust.


I'm all for faithfulness and trust, just not monogamy.


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## Darxus (May 10, 2010)




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## Duncan (Dec 8, 2008)

Use the driver as a structural member!!

I like it!!


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## Duncan (Dec 8, 2008)

On a more serious level I rode my two wheeled recumbent bike with a load of luggage on the rear carrier and it went into a horrible torsional resonance

Even if you don't have the twist from the tires if you are too flexible in torsion you can suffer!!


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## TomA (Mar 26, 2009)

toddshotrods said:


> The best bet for the combined goals, as stated, it it to first invest in some really good software with FEA capabilities, and spend more time learing that software than actually trying to build. He could then model his ideas, run an analysis, and see what the results would be. Once he modeled the main monocoque chassis attaching a 200-400 pound pod to it, with different methods and seeing where the stress and resultant failures, would be relatively simple to do. Advanced engineering is a mouse click away in the 21st century.


I actually disagree. That's a huge investment in time and software with a very uncertain outcome or payback. The project is already cash-strapped. Its just too much to bite off and risks getting anything made at all. 

Moreover, just because you can model something in 3D and render the surfaces and even convince yourself that you've done all the necessary math, it still has to be built, and the process of making anything in the flesh is going to be full of surprises. That's my experience, anyway.

TomA


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## toddshotrods (Feb 10, 2009)

TomA said:


> I actually disagree. That's a huge investment in time and software with a very uncertain outcome or payback. The project is already cash-strapped. Its just too much to bite off and risks getting anything made at all.
> 
> Moreover, just because you can model something in 3D and render the surfaces and even convince yourself that you've done all the necessary math, it still has to be built, and the process of making anything in the flesh is going to be full of surprises. That's my experience, anyway.
> 
> TomA


I think you missed my point. That it's a huge investment in time and software, *is* kind of my point. The stated goals of the project are beyond the scope of the amatuer, backyard, builder. They are more suited to a university that is pursuing the project as an engineeirng challenge. In that case the software makes sense because the point is engineering, not the vehicle.

As stated, the goals make the project impractical and potentially unsafe. It would be far wiser to spend the money on software, and learn something than build something that can potentially hurt himself and possibly others.

I think you also underestimate the capability of modern software. Properly modeled, they're not just a bunch of pretty rendered surfaces. A real solid model is an exact representation of a real-world part, and the computer does the math. That's how modern vehicles (and practically everything else) are designed. The computer shows a pretty picture of your model with various colors indicating stress, heat, whatever you request. Behind that picture is more math than a human could possibly accomplish in the same amount of time.

Gotta love technology...


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## TomA (Mar 26, 2009)

Todd, I get all of that. Being CAD illiterate doesn't make me ignorant...

There's still a big and tedious difference between the model and the part. Take one tiny example- the motor end bell mounts on your roadster. Theoretically, this is a simple translation of your design file to a CNC file to the finished part popping off the mill- but it hasn't worked out that way, and it is still a surprisingly tricky thing to get something made, even with full digital control. You have many hours in it, and years of experience.

I'm not beating up on you, you've got tremendous skills and your builds are stunning, but you're all the way at the digital end of the spectrum, and that actually isn't how most scratch-built vehicles are made. Passenger cars, tennis rackets, everything else for volume manufacture, yes, but generally not one-off cars with minimal budgets. 

My point wasn't that the digital design phase wasn't valuable or even essential, which on this project we probably both agree it is. I was just pointing out that all that work is just a prelude to trying to build the rendered design, and that can be very, very hard, especially when the modeling creates shapes and structures without regard to fabrication realities. 

At the end of the day, I guess Darxus has to decide whether he wants to build a trike, or embark on a self-taught CAD/CAM engineering program.

TomA


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## toddshotrods (Feb 10, 2009)

TomA said:


> Todd, I get all of that. Being CAD illiterate doesn't make me ignorant...
> 
> There's still a big and tedious difference between the model and the part. Take one tiny example- the motor end bell mounts on your roadster. Theoretically, this is a simple translation of your design file to a CNC file to the finished part popping off the mill- but it hasn't worked out that way, and it is still a surprisingly tricky thing to get something made, even with full digital control. You have many hours in it, and years of experience.
> 
> ...


I think we're probably in near total agreement, just expressing it from different perspectives. I certainly didn't mean to infer that you are in any way ignorant - even with CAD. Your experience and wisdom are self-evident in your posts. I just didn't know if you were aware of how much modern software is capable of - on an everyday computer. My interest was more in keeping him safe. I suggested the software more as a means of safety (considering the technical issues he's proposing) than a cure-all solution.

I have more experience working with my hands in fabrication than I do behind the computer screen, so I understand your points and agree 100%. Your points on translating digital design into real-life parts are also well-taken. Eric, my CNC machinist, has a PhD in engineering, and a shop full of awesome equipment, and we still had a few issues in the process. One that note: the rear mount is officially out of the clamps and in my hands now. You haven't seen anything yet!  That was one of my less-complicated designs. 

My original (and real) suggestion was really to build a more conventional EV first, and work on this one in the background. The point of the software is it would take time to master, and then time to accurately model, and then time to implement. Along the way Darxus would learn a LOT about design and engineering, and hopefully build something safe when he finally gets around to this monocoque concept. The software isn't a cure-all, but it would do the same thing we have been doing - tell him when he's about to get himself into trouble.

Honestly Darxus, I think you should find an old motorcycle, convert it to a reverse trike EV, and have fun building your first aluminum body shell. You will learn a lot about fabrication, a lot about EVs and reverse trikes, and have a much better foundation to start on for the monocoque. It may even be possible to design so that the components from the motorcycle-based trike can be used on the monocoque later.


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## Darxus (May 10, 2010)

Duncan said:


> Use the driver as a structural member!!
> 
> I like it!!


Oh believe me, I've considered it. Although more in the crouching position. Thanks.


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## Darxus (May 10, 2010)

TomA said:


> At the end of the day, I guess Darxus has to decide whether he wants to build a trike, or embark on a self-taught CAD/CAM engineering program.


I don't feel a need to decided. Wandering in either direction is fine with me.

I guess it was too vaguely implied that along with dropping the rear seat I also expect to drop the monocoque. 




Duncan said:


> ...torsional resonance...


Good term, thanks.


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## Darxus (May 10, 2010)




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## Darxus (May 10, 2010)

Frame.









Body. Nurbs surfaces are _fun_.


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## Darxus (May 10, 2010)

*Crouching*

If you're interested in driving in a crouching position, I recommend looking into formula 1 sidecars. I guess they were once motorcycles with sidecars used for racing. Now they vaguely resemble that layout. One of the amusing things is the passenger, the monkey. They climb all over the back of the thing to optimally balance weight in turns. You know that trunk monkey commercial? That's where they got the term. People talking about making a mechanical monkey to put in the trunk of their car.


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## DavidDymaxion (Dec 1, 2008)

The design reminds of me a Salt Flats electrathon racer. What a completely awesome meld of minimalist, yet era-independent beauty!


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## Woodsmith (Jun 5, 2008)

Darxus said:


>


How would the human body cope with road shocks and vibrations being imparted on the flat of the spine and the back of the head?

I would have huge concerns over visibility for anything other then the drag strip or the salt flats record attempt.


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## Guest (Jun 7, 2010)

You said you wanted it to be 35 inches high. Is this going to be for public roads? My car is 45 inches to the top of the roof and I sit pretty straight up with my legs stretched out. Sometimes in traffic I still fell like I’m in a canyon. The tires on my 4X4 are 32 inches tall and there are bigger ones than that out there. I think for comfort and the illusion of safety you should rethink the height equation.


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## toddshotrods (Feb 10, 2009)

Darxus said:


> Frame.
> 
> 
> 
> ...





Woodsmith said:


> How would the human body cope with road shocks and vibrations being imparted on the flat of the spine and the back of the head?
> 
> I would have huge concerns over visibility for anything other then the drag strip or the salt flats record attempt.





notmrwizard said:


> You said you wanted it to be 35 inches high. Is this going to be for public roads?... I think for comfort and the illusion of safety you should rethink the height equation.


I don't know whether to be somewhat encouraged that you've decided to use a conventional frame, and see it as progress; or to give up, and think a reasonable, practical, EV is just not going to happen here.

Darxus, you have a passion for exotic concepts, which I understand - I like radical concepts myself. Reality is what it is though, and we have to exist in it. Kudos for making a step towards a reasonable effort that is not so technologically challenging as to be out of reach for anyone outside a major company or university. You've "balanced" that by going completely off the deep-end with the layout again though. 

From danger to yourself, of being completely pancaked, cartoon-style, by even small cars that are surely not going to see you; and danger to pedestrians who just aren't going to be looking for something like that - especially with it being a relatively silent EV, it's just not a practical idea for anything other than a dedicated *off-road* race car. I can just see someone stepping off a curb in front of you, at the last second, because they are too busy in our world of a million distractions to even consider looking for a two-feet tall land-speed style EV on the street. I even changed my first plan for my e-bike because the seating position was too low for public roads.

The certainty of fatigue from driving with your head cranked forward so far, and the fact that good aerodynamics can be achieved with a taller profile, are facts that have already been covered, so it's starting to seem pointless. There are just certain boundaries that we have to respect as members of a society.


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## Darxus (May 10, 2010)

*Height*



toddshotrods said:


> I don't know whether to be somewhat encouraged that you've decided to use a conventional frame, and see it as progress; or to give up, and think a reasonable, practical, EV is just not going to happen here.


I have been pleasantly surprised at how seriously I've been taken here so far, and how much useful feedback I've gotten. I really appreciate it.

But it's probably safer to expect no reasonable, practical EV is going to happen here.

"The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man." - George Bernard Shaw



toddshotrods said:


> You've "balanced" that by going completely off the deep-end with the layout again though.


Hah. Thank you. (For the suggestion to raise the seating position.)



toddshotrods said:


> From danger to yourself, of being completely pancaked, cartoon-style, by even small cars that are surely not going to see you; and danger to pedestrians who just aren't going to be looking for something like that - especially with it being a relatively silent EV, it's just not a practical idea for anything other than a dedicated *off-road* race car. I can just see someone stepping off a curb in front of you, at the last second, because they are too busy in our world of a million distractions to even consider looking for a two-feet tall land-speed style EV on the street. I even changed my first plan for my e-bike because the seating position was too low for public roads.


I have been considering these problems all along. Although not specifically pedestrians. Riding motorcycles year round in Boston is educational. I get the impression most people, at best, try to drive to avoid getting in an accident. I spend a lot of my attention more specifically on not allowing people to be able to hit me. People really just don't see motorcycles, because they're not looking for them. They're looking for cars and maybe pedestrians. Brains are funny. I drive / ride quite defensively.

I realize this doesn't take away the danger of such a small vehicle being harder to see.

My latest iteration actually has a very slightly more upright seating position (along with one fewer wheel). And I will look into raising it further. (I realize inertia well above the ground is likely to be important to the stability of a motorcycle).

At worst, I hope you'll check back once a year or so to see if I've ended up with something more practical.




DavidDymaxion said:


> The design reminds of me a Salt Flats electrathon racer. What a completely awesome meld of minimalist, yet era-independent beauty!


Yikes, that thing is impressively tiny. I'll have to see if I can find info on its internals.




notmrwizard said:


> You said you wanted it to be 35 inches high. Is this going to be for public roads? My car is 45 inches to the top of the roof and I sit pretty straight up with my legs stretched out. Sometimes in traffic I still fell like I’m in a canyon. The tires on my 4X4 are 32 inches tall and there are bigger ones than that out there. I think for comfort and the illusion of safety you should rethink the height equation.


I don't have any specific height goals, just minimal frontal / wetted surface area.
Thanks.


I was looking at wireframe orthagonal side view, where you can't tell how many front wheels it has, and thought "That would be sick as a motorcycle.
Hmm." I wasn't going to post this yet, but while I'm posting:

[Accidentally overwritten.]

Yes, I was affected by Akira. This currently shares, with Kaneda's power bike, insufficient clearance to lean far enough to turn.


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## Darxus (May 10, 2010)

DavidDymaxion said:


> The design reminds of me a Salt Flats electrathon racer. What a completely awesome meld of minimalist, yet era-independent beauty!


"He covered 62.05 miles in one hour with an energy efficiency equal to 2,200 miles per gallon..."
"Power is limited to 67 lbs. of production lead acid batteries, which amounts to a little more than one horsepower over the hour."

Damn.

http://evmaine.org/html/worldrecord.html
http://endless-sphere.com/forums/viewtopic.php?f=7&t=12542

Distinct similarities.


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## toddshotrods (Feb 10, 2009)

*Re: Height*



Darxus said:


> I have been pleasantly surprised at how seriously I've been taken here so far, and how much useful feedback I've gotten. I really appreciate it...


This is a great group, and one that is always willing to stretch itself - I'm speaking from experience because I am unconventional too, and have received the same type of support. That's also why it's wise to at least seriously consider the other side of the coin that's presented. I was able to maintain, and actually improve, my vision while being mindful of some of the pitfalls that were pointed out.




Darxus said:


> ...I have been considering these problems all along. Although not specifically pedestrians. Riding motorcycles year round in Boston is educational. I get the impression most people, at best, try to drive to avoid getting in an accident. I spend a lot of my attention more specifically on not allowing people to be able to hit me. People really just don't see motorcycles, because they're not looking for them. They're looking for cars and maybe pedestrians. Brains are funny. I drive / ride quite defensively...


I relate to that 100%. I started riding on the street in 1983. Defensive riding is the best route to returning home alive, or at least in one piece. It's just that there's only so much you can do to prevent some situations. A two-wheeled motorcycle offers you the option of bailing out (something I have actually had to do) while the more enclosed a motorcycle becomes the more you have to consider car-like options. Options you would have to avoid an accident on a two-wheeled bike may not be available with two wheels spread out in front of you, and a body keeping you locked into the situation.




Darxus said:


> ...At worst, I hope you'll check back once a year or so to see if I've ended up with something more practical...


You won't get rid of me that easy!  I have no reason to be offended or frustrated and walk away, this is your project. I am confused as to what your actually pursuing, which can be mildly frustrating, but also intrigued to see what conclusions you reach; and what progress you make.




Darxus said:


> ...But it's probably safer to expect no reasonable, practical EV is going to happen here....


Reasonable and practical are relevant, subjective, terms. If memory serves me right, your goal is to use this for transportation to school(?). Reasonable and practical for you are something that meets your goals for efficiency and function, but also actually gets you there alive, right?  It's not an attempt to get you to build what we want you to build, just to help you safely meet your stated goals. It can be totally unreasonable for everyone here but you, but completely reasonable and practical for your needs. My race rod isn't exactly practical for proably 90% of the people on this forum, but it's carefully planned for the context in which it will be used. Just don't challenge reason and practicality just for the sake of challenging it.




Darxus said:


> ..."The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man." - George Bernard Shaw...


That's an awesome quote, the principals of which I have probably lived by for most of my life. Everything has context though, and everything needs balance. I'm sure the author wasn't speaking of being unreasonable just for the sake of being different. Going against the laws of physics is unreasonable, but I doubt the end results will hold much progress.


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## TomA (Mar 26, 2009)

*Re: Height*



toddshotrods said:


> Reasonable and practical are relevant, subjective, terms. If memory serves me right, you goals is to use this for transportation to school(?). Reasonable and practical for you are something that meets your goals for efficiency and function, but also actually gets you there alive, right?  It's not an attempt to get you to build what we want you to build, just to help you safely meet your stated goals.


I think the playful disconnect is right here.

Its clear to me that the primary goal is "cool vehicle that I want to build," which is great, and that all the other considerations about purpose, range, speed, etc. are completely secondary.

As someone who commuted to work in a Big Block Stingray (when they were just used cars that were hard to keep on the road,) I completely understand "practical" as, say, "operable on the street in the absence of precipitation, traffic control devices or other vehicles..." but it has taken a few weeks for me to figure that out about this project.

Its a toy. The disconnect is that you are bumping into guys who are probably a little older and more risk-averse than you, and think you're serious about putting your loved ones in the backseat and going back and forth to school. Maybe you are. Don't get me wrong, I've been a bicycle messenger, (hit 4 times) a mountaineer, street racing bad-boy and many other risky things, but I don't do things now the way I used to, and don't advise people to do so, either.

There's something else, too. You seem to care a lot less than others whether and how this thing comes together. That's cool, I've been there, too. At my age and with the limited time I have for projects now, though, I'm not interested in producing stuff that winds up stillborn or crippled. There's an implication when asking for help from a group like this that you're actually focused on successfully completing a build, and want help making it efficiently and safely. Those clearly aren't priorities for you. Again, not a criticism, but good to know.

I still want to see this thing in the flesh, if only on a trailer, and I encourage you to follow your bliss and make it happen.

TomA


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## toddshotrods (Feb 10, 2009)

*Re: Height*



TomA said:


> I think the playful disconnect is right here...


 Yeah, I get your points Tom. I am not even exactly risk-averse - I'm building a 1200lb/90"wb hot rod that I plan to push to its physical limits. I have always lived this way, and probably will for at least a couple more decades. The thing is I am probably still here because I have always had a very diverse group of peers. The oldest guy in our group, when I was heavy into drag racing motorcycles, was 33 years my senior; and most of the guys had at least a decade or so on me. I had enough sense to listen when they seemed alarmed at some crazy plan I had. I guess I am just trying to pay it forward and be the voice of reason for someone who reminds me of myself...

Now if you really do just want to build a cool toy, don't mind trailering it around, and only driving it in controlled environments - I'm all for it. Safety is still the number one priority, but it does open doors to other possibilities. Build one of those little racers, take it to shows and events, and maybe even get to race it someday. I won't lie, that little Electrathon racer makes me want to build one.  I would just know better than to even consider taking it out on streets with real-sized vehicles, with drivers on cell phones, putting on their make up, shaving, daydreaming, etc.


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## Darxus (May 10, 2010)

*Re: Height*



toddshotrods said:


> I am confused as to what your actually pursuing, which can be mildly frustrating...


Sorry about that. I want a toy I can commute to work in, 70 miles 5 days a week. One of my motivations is how much I have enjoyed motorcycles and hated the tedium of gearing up for riding in bad weather.




TomA said:


> The disconnect is that you are bumping into guys who are probably a little older and more risk-averse than you...


I'm 33, and less risk averse than average.



TomA said:


> You seem to care a lot less than others whether and how this thing comes together.


Maybe. I want it too. But I realize it's unreasonable.


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## Darxus (May 10, 2010)

Oh, new pictures included two potentially not obvious changes: Smaller motor, and smaller charger, based largely on http://experimentalev.wordpress.com/
Blog of race bike conversion.

The much thinner "Etek type" ET-RT motor works out so much better than the Impulse 9. I don't know if anybody noticed, but I had been reducing the width of the final drive with a couple gears on a shaft so the tail end wasn't as wide as the Impulse 9. And I think this ET-RT should do just fine. 72v 150 amps continuous. The batteries in the model are four Trojan T-1275's totaling 48v, 150AH @20 hour rate.

The charger dimensions are of a Soneil model number 7203SR, 72 volt charger, dual voltage (100/240) input. Tiny.


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## Darxus (May 10, 2010)

Streamliner motorcycle front suspension and steering, from http://www.pebblecreekskiarea.com/mikes/bub.htm

Yamaha GTS 1000 single swingarm front suspension is close to usable, except for the actual steering mechanism. The only other thing I'd seen before is the double front swingarm on the Veyrus which looks complicated and expensive.


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## TomA (Mar 26, 2009)

Darxus said:


> Streamliner motorcycle front suspension and steering, from http://www.pebblecreekskiarea.com/mikes/bub.htm


Hmm... The caption on the photo says: "They could not get it to go straight..." On a flat course with no turns, that's really saying something.

TomA


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## Duncan (Dec 8, 2008)

Hi Darxus

I like the more advanced steering system - the main reason motorbikes have horrible fork systems is that racing rules have required them and road bikes "must" look like racers!

I have ridden recumbent trikes and I personally think they are too low!
I was terrified!!

If you want low frontal area then I believe a leaning trike is the route to go, with this you can go higher for visibility and to see more
(On my recumbent two wheeler my friends on normal bikes could see over hedges that blocked my vision)
The only additional frontal area is the thickness of your (faired) wheels


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## Darxus (May 10, 2010)

TomA said:


> Hmm... The caption on the photo says: "They could not get it to go straight..." On a flat course with no turns, that's really saying something.


Yup. After I posted that I realized I couldn't find the necessary pivot points in the picture. Maybe they were hoping to be able to usefully flex... the hub? Definitely not going to exactly mimic that.



Duncan said:


> I like the more advanced steering system - the main reason motorbikes have horrible fork systems is that racing rules have required them and road bikes "must" look like racers!


I seriously hate when that happens. 



Duncan said:


> I have ridden recumbent trikes and I personally think they are too low!
> I was terrified!!
> 
> If you want low frontal area then I believe a leaning trike is the route to go, with this you can go higher for visibility and to see more
> ...


I know 

Since I dropped the rear seat, and that significantly reduced complexity, bulk, and weight, I think only two wheels would work okay (probably with Ecomobile style outriggers). Although I haven't raised the height significantly, because I believe I'll like it more very low.


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## DavidDymaxion (Dec 1, 2008)

It could be that bike or that design has inherent problems, but running on the Salt Flats has it own challenges. It's slippery -- I have seen motorcycles suddenly break the rear wheel loose in 4th gear. Sometimes the salt has potholes or ruts. The speeds are very high. One very experienced motorcycle racer I spoke with took out a mile marker near 200 mph -- he said things happen so quickly at that speed he suddenly found himself on the course boundary. He was riding a stock Suzuki. Something else that happens is aerodynamic effects dominate. I have seen videos of streamliner motorcycles that steadily hold a surprising lean angle -- even though they are still going straight!

The problems are not just for motorcycles. You'd be surprised how many cars spin out.

So anyway, it could be a bad design or bad implementation, but in any case the challenges of land speed racing can make it hard to stay straight.


TomA said:


> Hmm... The caption on the photo says: "They could not get it to go straight..." On a flat course with no turns, that's really saying something.
> 
> TomA


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## TomA (Mar 26, 2009)

DavidDymaxion said:


> It could be a bad design or bad implementation, but in any case the challenges of land speed racing can make it hard to stay straight.


I agree, and I think actually in this case its both, or all three. These guys should have gone to the paved Maxton Mile before trying the salt, which might have helped them figure out why it won't steer properly without the compounding impact of the dry lakes. Of course, Maxton is narrow, and has a little jog turn at the beginning of the course, which might have been a disaster for this rig. Now there's Loring AFB in Maine, which is a wider paved runway. That's where I'll take my trike, hopefully next year.

The trouble is, those swing arm motorcycle front suspensions with hub-centered steering are a fair amount harder to make work than most people realize. I remember when the _Tesi _first appeared about 20 years ago. Tesi is Italian for "thesis," e.g. doctoral thesis, which is where that front suspension started. Not a particularly good garage fabrication project...

TomA


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## toddshotrods (Feb 10, 2009)

TomA said:


> I agree, and I think actually in this case its both, or all three. These guys should have gone to the paved Maxton Mile before trying the salt, which might have helped them figure out why it won't steer properly without the compounding impact of the dry lakes. Of course, Maxton is narrow, and has a little jog turn at the beginning of the course, which might have been a disaster for this rig. Now there's Loring AFB in Maine, which is a wider paved runway. That's where I'll take my trike, hopefully next year.
> 
> The trouble is, those swing arm motorcycle front suspensions with hub-centered steering are a fair amount harder to make work than most people realize. I remember when the _Tesi _first appeared about 20 years ago. Tesi is Italian for "thesis," e.g. doctoral thesis, which is where that front suspension started. Not a particularly good garage fabrication project...
> 
> TomA


Yeah, I remember drooling over magazine articles and pics of the Tesi, and then the RADD bike. Now I realize that those exciting concepts just sort of faded into the sunset. I wouldn't doubt that the biggest problem with all the alternative concepts is more about production feasibility though. I seem to remember the magazine guys raving about how well the RADD bike handled, but there are a lot of things to get right or wrong on an assembly line...

Darxus why are you abandoning your reverse trike format? A couple suspension arms on each side, and an extra wheel can't be _that_ much of an issue. You could use the tear-drop shaped aircraft tubing for a little better aero properties. I have heard reports of cracking with it, but not sure if that was a specific manufacturing thing or the design of the tubing itself.


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## Darxus (May 10, 2010)

toddshotrods said:


> Darxus why are you abandoning your reverse trike format?


I just don't feel a need for the third wheel with the reduced bulk and weight.


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## Duncan (Dec 8, 2008)

Hi Darxus

I gather you are going for a two wheeler - so you lean into corners

From my recumbent experience 

Don't go low
Assuming that you are going to put a "foot" down to stop
Low bikes - your leg is not "under you" this can be dodgy - foot slips and you are over

Very low bikes the rider uses his hand - think dog poo!

Low bikes are more difficult to balance! - the inverted pendulum try balancing a meter stick on your hand (on end) - now try with a six inch rule

Low bikes - you can't see (the blond) over the hedge! 
or the road ahead

Low bikes
Maniacs in cars cannot see you
In high cars (the worlds worst drivers like SUV's) they physically can't see you


High bikes fix all of this for a tiny increase in frontal area - which may be compensated for by moving your vehicle further out of the ground effect

My recumbent had my eyes at the same level as in a medium sized car - about 300mm lower than a mountain bike riders eyes
higher would have been better 
about the same as a mountain bike


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## Darxus (May 10, 2010)

EMC-R / Mars ME0708 "is a direct replacement for the Briggs & Stratton Etek motor, which has been out of production since 2003. Runs a little faster than the Perm and Lynch or Lemco motors" The EMC-RT / ME0709 is 2.5cm (1") wider and rated for 72 volts instead of 48 volts.


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## sunworksco (Sep 8, 2008)

Here is a good inexpensive example.
Regards,
John


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## Darxus (May 10, 2010)

sunworksco said:


> Here is a good inexpensive example.
> Regards,
> John


Nice, thanks. Where did that picture come from?


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## sunworksco (Sep 8, 2008)

http://rohorn.blogspot.com/


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## Darxus (May 10, 2010)

sunworksco said:


> http://rohorn.blogspot.com/


Neat stuff there, thanks. This vehicle has two wheel steering and drive, which is cute. But no suspension. The combination of suspension and steering is what is challenging me.










What I really want is some kind of, er, quadruple swingarm? Attached to an upright on each side of the wheel.


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## toddshotrods (Feb 10, 2009)

Sounds like a BMW Tele-lever (sp?) motorcycle front suspension.


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## Darxus (May 10, 2010)

toddshotrods said:


> Sounds like a BMW Tele-lever (sp?) motorcycle front suspension.


Nah, those have two pivoting joints. I'm trying to come up with a way to have nothing above the wheel at all.


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## Darxus (May 10, 2010)

This is more along the lines of what I'd like to do.


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## sunworksco (Sep 8, 2008)

sunworksco said:


> Here is a good inexpensive example.
> Regards,
> John


This bike is front/rear variable rate steering.
Regards,
John


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## Darxus (May 10, 2010)

That's about what I'm thinking. Not structurally sound yet of course. 
The orange bits are just there to show frame attachment points. 

The pivot points probably aren't obvious, so this is probably useless to anyone but me


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## toddshotrods (Feb 10, 2009)

Why not just two single-sided swingarms with a short automotive knuckle, and conventional automotive balljoints. The steering linkage comes in near axle height, and there's nothing even close to the top of the tire. They could even be fabricated from sheet aluminum or steel and welded up. Using arms on both sides of the wheel is going to over-complicate the h#!! out of it, trying to get it to pivot properly, and won't contribute anything necessary. Have the rotor and/or hub re-drilled for it, and you may be able to use a single-side motorcycle wheel.


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## Darxus (May 10, 2010)

toddshotrods said:


> Why not just two single-sided swingarms....


Mostly because I don't like single sided swingarms. They're lopsided. I'll do it if I can't come up with something I like more though.


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## Darxus (May 10, 2010)

Kaneda's power bike from Akira.

http://www.youtube.com/watch?v=ESkO94iUm34
Picture from http://www1.odn.ne.jp/cbt14030/3dcg/kbike.html


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## toddshotrods (Feb 10, 2009)

Darxus said:


> Mostly because I don't like single sided swingarms. They're lopsided...


I agree. I've never been a big fan of them because I tend to prefer symmetrical designs in vehicles. They are a thousand times more practical though for a front swingarm setup. Have fun.


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## Darxus (May 10, 2010)

Did math comparing lead acid and lithium ion again:

For 10,800 watt hours (80 watt hours per mile x 100 miles, rounded up to the next T-1275):

Trojan T-1275 12v (x6 = 72v) flooded lead acid:
$870
222kg (492lbs)

Thunder Sky lithium ion:
$4033 (4.6x)
118.4kg (261lbs) (30%)
73% of the volume

I had been thinking lithium would save me significantly more space.


The Mars ME0709 / Etek RT motor is rated for a little over 3,000 RPM. At 105kph (65mph), estimating tire diameter from the Ducati stuff I had been working with, I'm coming up with a rear sprocket about 3.16x the size of the front sprocket. This seems like a much smaller gear reduction than most people seem to be using with this motor (on motorcycles), which concerns me.

At the moment I'd like to use a front / rear wheel pair off a common large motorcycle that is not shaft driven. Like a Goldwing, but not shaft driven. Everything big has a freaking shaft. Maybe Honda Blackbird (have one)? Have I mentioned I like Honda?


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## TomA (Mar 26, 2009)

Why not go with the Harley belt drive? Lots of wheel choices there, and a pretty efficient drive that would be easy to work with.

You are doing apples-to-oranges comparisons with the batteries. Ampere-Hour ratings are not interchangeable between chemistries. An SLA battery is really only good for a fraction of its C/20 Ah rating in an EV high current drain situation due to Peukert's effect. The Lithiums are better in the high drain environment, and their Ah rating is given at 1C, I think. I can't see your math so I don't know what your assumptions were. Did you correct for this difference in the way the batteries are rated and perform?

No matter, really. The short answer here is: Lead is dead. Go with the Lithiums.

TomA


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## Darxus (May 10, 2010)

TomA said:


> Why not go with the Harley belt drive? Lots of wheel choices there, and a pretty efficient drive that would be easy to work with.


Because I thought they were very rare on production motorcycles. I had no idea they were standard on Harleys since 1984. Thanks. I'll probably use that.



TomA said:


> You are doing apples-to-oranges comparisons with the batteries.


Yeah. I was mostly disappointed with the space savings. I was using the 20 hour amp rating of the Trojans and not compensating for the differences at all. Which I realize is not very useful. It would be nice if there were math that more clearly described the relationship. The info in the wiki on this site is confusing. 

I'm planning to prove the concept with lead acid and then consider switching to lithium.


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## TomA (Mar 26, 2009)

Darxus said:


> I'm planning to prove the concept with lead acid and then consider switching to lithium.


I don't recommend that. Its a little like making an airplane out of wood first, then trying to remake the same plane again out of aluminum. Lots of reconfiguring of practically everything is required.

Do it with Lithium cells, and if you want to save money, you don't absolutely need to start with the full pack day one, adding incremental cells over time.

TomA


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## Duncan (Dec 8, 2008)

Hi Darxus

I think you are overegging the batteries,
You are designing something like an HPV streamliner - the hour record on these is over 50 miles, the flying quarter mile is over 70mph

Conservatively at 60 mph you *must* be using less than 240 watts,(one people power)
(A normal person can only put out 50 watts continous (1 hour rating)

This is one mile a minute therefore 240 watt minutes / mile or 4 watt hours/mile
Multiply that by a huge margin for error, you get 10 watt hours/mile

At that level you have specified a *1000 mile* battery pack!

I think you should be looking at a 1Kwhour pack, about 12Kg of batteries not 120Kg! 

Should be a lot easier to package! cheaper too

And you are back to push bike weights for the rest of your components


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## Duncan (Dec 8, 2008)

Hi Darxus

Single sided swinging arms

While inelegant millions have been made and used, every mini (the proper ones) has two on the back, as did a lot of other makes.

if you calculate the loads and deflections you can see that while inelegant they are quite light and stiff


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## Darxus (May 10, 2010)

Duncan said:


> While inelegant millions have been made and used, every mini (the proper ones) has two on the back, as did a lot of other makes.


Yeah but the Minis are symmetrical.


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## TomA (Mar 26, 2009)

Duncan said:


> Hi Darxus
> 
> I think you are overegging the batteries,
> You are designing something like an HPV streamliner <--snip-->
> ...


I put the requirement about halfway between you guys... 

A steel frame, the EV powertrain and motorcycle parts are going to push this vehicle to 500-750lbs. That's three or four times the mass of a 'liner bike or even a velomobile. Lots more drag, too.

Look at it a different way: Let's say it was ICE powered. Would it be as efficient as the world record holding 230lb California Commuter that achieved 155mpg? Let's say yes! 

If so, you would need about 2/3 of a gallon of gasoline to go 100 miles in it. Using the rough equivalency of 8kKh of Lithium cells equalling a gallon of fuel, you need .66 gallons x 8kWh of Lithium x 1.25 (so you go to 80% DOD, not 100% on every 100 mile duty cycle) = 6667Wh of Lithium batteries. Assuming a nominal voltage of 3.2V, that's about 2085 Ah of cells.

There are a few ways to get that in prismatic cells. 52 40Ah cells would be about 185 lbs. 35 60Ah cells would be about 177 lbs. 23 90Ah cells would be about 152 lbs. It just depends on what voltage and current compromises you want to make. A123 and other Lithium chemistry options would probably be even lighter. For myself, I'm going with 48 40Ah cells- 165 lbs, in a trike with a gross weight under 500lbs and very good aero. I don't expect to go more than 60 miles on it without stressing the cells.

Moreover, if Darxus' vehicle can't match Doug Malewicki's 230lb world record car for efficiency, it would be wise to enlarge the pack a little if that 100 mile range is a drop-dead requirement.

Just a different way of noodling it...

TomA


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## Darxus (May 10, 2010)

I just reduced my range requirement by half.

I'm going to mount the batteries and charger on a removable hand truck, and wheel the pack inside and charge it while I'm at work if necessary. 

Mars ME0709 (Etek RT), Alltrax AXE-7245, and the smallest possible Thunder Sky 72 volt pack (22x 40ah 3.2v = 2.8 kWh) all sounds sane, right? If that won't do it I'll double the pack size, split into parallel halves.

And should I do a 22 cell 70.4v pack, or 23 cell 73.6v pack? How do 72v chargers feel about not exactly 72v packs?


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## Darxus (May 10, 2010)

What's the maximum gear reduction on a Harley final drive? Max I'm finding is 2.69 with a 26 tooth front and 70 tooth rear. And I think I want about 3.16 (to get the motor to 3,000 rpms at 105kph (65mph)). 


Oh, I keep forgetting to ask: Do the capacitors in controllers basically just act as a sort of electrical flywheel, smoothing the output pulses?


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## Duncan (Dec 8, 2008)

Hi TomA

155 mpg does not seem to be very good for a world record 2 wheel streamliner, I am sure VW built a four seater car that beat that

The world record for petrol "cars" is over 2000 mpg 

The choice is between an electric streamlined *bike* with about 500 watts power and 60Kg weight and
an electric streamlined *motor bike* with 5000 watts power and and 300 Kg weight

I like the Amory Levin approach where you make things lighter so that you can make other things even lighter


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## TomA (Mar 26, 2009)

Duncan said:


> Hi TomA
> 
> 155 mpg does not seem to be very good for a world record 2 wheel streamliner, I am sure VW built a four seater car that beat that


No, the VW 1-liter car is a two-seater and was designed to get about 240mpg, but it can't do highway speeds and was not actually road tested. It holds no records. The production 2-seat version (promised for 2013, but will probably never be offered) has gone from a claimed 189mpg to now around 170. Still no data. Interesting how the more VW works on the concept, the less fuel efficient it gets...

http://www.popularmechanics.com/cars/news/fuel-economy/3374271

The California Commuter is a trike, but the frontal area is very small, about the same as a motorcycle, although Darxus' recliner will be even less.

Sure, there are four-wheelers with higher mpg, after all it has been over 35 years, but none are garage built or use commonly available parts and systems. 



> The world record for petrol "cars" is over 2000 mpg.


Those are engineering toys that use 50cc engines to pulse and glide around 25mph. That's like comparing the the energy consumption of the Gossamer Condor to a VariEze. Fuel economy in a road vehicle in uncontrolled public traffic is a very different thing. I'm not aware of any vehicle that has actually broken the California Commuter's records. I'm not saying it hasn't been done in the last 3 1/2 decades, but I haven't seen it... 

Doug Malewicki's record is very impressive. We are always inundated with higher number claims in press releases and magazine puff pieces, so it doesn't seem like much, but consider: Where are these other high mileage machines? Are they street legal? Can you buy one? Can you order the plans and make one in your garage? Where are the official records they have set, and under what sanctioning body were they certified?

It turns out that most if not every single one of these other super-high mpg machines is packed with unobtainable one-off OEM or university research technology, and has only been run at ideal speed on closed course test circuits. Moreover, the claims are almost always uncertified by a third party, so in fact no one outside the company or engineering team really knows what they can do.

None of that matters here, though. Darxus should look at the EV album and see what the motorcycles and smallest cars are using energy-wise, and estimate his consumption by comparison from there. I just don't think faired bicycles, electrathon racers, velomobiles or the like are going to provide comparable data for accurate estimating

TomA


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## Duncan (Dec 8, 2008)

Hi TomA

Five minutes on Google got this

http://www.craigvetter.com/pages/470MPG/Vetter%20Fuel%20Economy%20Contests.html

_In 1980, nobody knew. I thought it was time to find out. Between 1980 and 1985, I sponsored the Craig Vetter Fuel Economy Contests. We learned how to get over 470 miles per gallon! On real highways - in real conditions_.

http://ecomodder.com/blog/diy-aero-fairings-honda-125cc-motorcycle-214-mpg/

The little Honda is interesting as it is an open fairing - feet down as usual

The one liter VW was being used by their technical guy on the roads - yes it was a two seater but it got 240 mpg

Of course if you want to go silly - 8923 mpg!!

http://www.inhabitat.com/2008/03/18/transportation-tuesday-8923-miles-per-gallon/


Basically if you design a superlight super slippery vehicle you can get away with a very very small battery pack

240 watts in a streamlined recumbent can equal 60 mph, which gives 4 watts/mile

I was suggesting a 250% - safety margin and 10 watts/mile

It is doable but 

Can you live with a full fairing?
Bomb doors for your feet?
Acceleration?
Fragility?

Saying all that and comments about putting money where mouth is I am building a toy two seater (Locost type) and I would be happy with 250 watts/mile


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## Darxus (May 10, 2010)

Quasar / Voyager hub center steering prototype from http://www.oesten-creasey.eu/hightech/pearly.htm
By Royce Creasey. Neat work. Around 1984? He recently showed up again with a design proposal for the TTXGP electric motorcycle racing series. 

This picture made me think that if I did a double wishbone front suspension along the lines of my recent front suspension / steering rendering, I could connect the handlebars to a pivot point above the front wheel with something like a CV joint. That seems simpler. Which is scary. But I think my only two options to avoid adding significant height for front steering are dual wishbone + CV joint type steering, or hub center steering.


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## Darxus (May 10, 2010)

I could also get crazy with control arms like this guy is trying to do: http://www.projectvf.com/
(He has certainly made a lot more progress than I have.)


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## Darxus (May 10, 2010)

I think sleeping on this helped. I think it would work better to have.. three things pivoting in parallel, I guess three instances of the steering head: At the wheel, at the handlebars, and at (and perfectly lined up with) the point where the wishbones mount to the frame. Then I can just run a pair of simple control arms.

The attachment is another recumbent motorcycle I found inspiring years ago that I've been keeping my eyes open for. It looks like it has some serious design problems, but it's pretty.


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## Darxus (May 10, 2010)

Supposedly someone will be selling hub center steering (HCS) wheels: http://www.isrbrakes.se/products/ns2/
Includes a nice video demonstrating function. They use cables for steering though, yuck.


Cute chick and HCS (Suzuki G-Strider concept).


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## Darxus (May 10, 2010)

I liked Duncan's comment about making it lighter so you can make it lighter. 

The battery pack isn't big enough for more then testing: Headway 10Ah 3.2v x 22 = ~72v.

Tire dimensions are from a Lifan LF200 (200cc motorcycle) as used in the converstion on http://www.electricmotion.org/ .
Frame based on http://www.wind-water.nl/rec_build_n.html (low recumbant bicycle).

The most important bits of the steering and suspension I'm currently interested in are included - double wishbone front with a steering linkage pivot intersecting the wishbone pivots.

The Lifan tires have tubes. How should I feel about that?


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## Darxus (May 10, 2010)




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## Darxus (May 10, 2010)




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## Darxus (May 10, 2010)

I realized the amount of parts I want from a Lifan LF200 motorcycle are close enough to a rolling chassis (everything but the engine) that I should probably just get the full rolling chasis and start off with just converting it to electric, as has already been done and well documented on http://www.electricmotion.org/
Initially using a small battery pack.

Then replace the frame with a steam bent 4x4.

Then decide if I want to add more batteries or a small gasoline generator to be able to get to work on it. 

The first series hybrid set the Austrian land speed record and was winning races over one hundred years ago, with (the first?) hub mounted electric motors, the Lohner-Porsche.

 (high-res video)


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## ewdysar (Jun 15, 2010)

Darxus said:


> I realized the amount of parts I want from a Lifan LF200 motorcycle are close enough to a rolling chassis (everything but the engine) that I should probably just get the full rolling chasis and start off with just converting it to electric, as has already been done and well documented on http://www.electricmotion.org/
> Initially using a small battery pack.
> 
> Then replace the frame with a steam bent 4x4....
> ...


Instead of a 4x4, I think that you would be better off from a strength to weight ratio by making a custom i-beam with thinner plywood for the vertical webbing and something no thicker than 3/4" for the top and bottom caps. You would have more choices in the shape and can tailor the beam to be thicker where it needs to be for strentgh and thinner at the ends to save weight. You could even build a box beam (think spruce and airplane spars) and run some of your controls or wiring inside.

Eric


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## TomA (Mar 26, 2009)

Darxus said:


> Then replace the frame with a steam bent 4x4.


The radius of the bend down by the riders feet looks like less than a foot. That's going to be quite a steam bending job...

Even a hollow wood box this size is going to be really heavy. It will rot and crack, too. Why is this better than an FRP composite or even a thin wall steel beam?

TomA


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## sunworksco (Sep 8, 2008)

Chrome-molly steel tubing for a frame this small can't be to heavy and you can use aluminum where you can lighten up the chassis.A $600.00 mig welder and some tubing could get your project going faster,too.You could design it with an F-800 BMW single-sided swing-arm.I bought a complete used unit off Ebay relatively inexpensive compared to new parts.I'm in Tom's camp about the rot factor.You might end up with a bad splinter center!
Regards,
John


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## ewdysar (Jun 15, 2010)

TomA said:


> The radius of the bend down by the riders feet looks like less than a foot. That's going to be quite a steam bending job...
> 
> Even a hollow wood box this size is going to be really heavy. It will rot and crack, too. Why is this better than an FRP composite or even a thin wall steel beam?
> 
> TomA


I only mentioned a wood alternative because his suggestion of a 4x4 indicated a preference for wood. That said, wood composite construction is a reasonable way to get good strength to weight ratios. There are still light planes being built that rely on the almost magical properties of wood. 

Personally speaking, my homebuilt 17' ocean kayak is thin plywood, regular 'glass and epoxy. It will not rot and won't crack under any conditions that a carbon composite would survive. It is the same weight but stiffer that a molded carbon fiber version of the same, way cheaper too. Could I build a lighter version using more exotic materials or methods, you bet, but the wood composite construction is a very good compromise.

I'm sure that you know that charcoal briquettes were invented to use the massive volume of wood chip manufacturing waste from the Ford auto plants. My 1400 pound Model T uses a considerable amount of wood in the structure. Sometimes it's easier to use what is availble and easy to work, especially for prototypes...

Eric


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## Darxus (May 10, 2010)

TomA said:


> Even a hollow wood box this size is going to be really heavy. It will rot and crack, too. Why is this better than an FRP composite or even a thin wall steel beam?


The radius actually gets down to about 15cm (6"), without having made any attempt to maximize radii. 

Mostly, I think wood would be fun. But you make it sound much more problematic than I had thought. Getting away with a bend that I'm happy with, and weight, are what you've concerned me most with.

If I custom welded up a steel square tube, what dimensions and steel would you recommend?

I ordered a trailer and hitch today. The closest Lifan shop has not replied to my email about picking up a rolling chassis.

I started thinking I should get the materials and a Miller Syncrowave 200 TIG and build the entire trailer too. And then I could build it into a camper. With solar panels. Or an RV.... So I just ordered the damn trailer.

I am amused by the possibility of one day saying "My house gets better mileage than your car."


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## sunworksco (Sep 8, 2008)

Eric,
You could use a 3" tube/spine and fill it with high density foam.
Regards,
John


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## michaelplogue (Jan 18, 2010)

I'm not sure if your goal is for breaking records, or to build something that could be used for daily commutes. If the later, I think you'll have a bit of difficulty making low speed turns with your feet and legs right along side the front wheel like that. 

And as mentioned before, if you plan on driving this in traffic, I think you'll be very uncomfortable being at eye level with the bumper of the cars in front of you - not to mention the fact that you will be very hard to see by other drivers on the road. 

Picture yourself lying down in a coffin that's sitting on roller skate wheels, tooling along in the middle of heavy traffic. Keep that image firmly in mind, because a vehicle this low in heavy traffic could very well turn into a coffin. Planning for the most efficient design is all well and good, but one should never, ever forget about safety. 

Then again, if this is for attempting speed/efficiency records and will only be used on an open track, then these sorts of safety concerns aren't as important.

Regarding the bending of a 4x4 for the main strut. This would not be possible with the radius shown in your renderings. However, it would be possible to steam bend thinner boards and pressure glue them into a single unit. However, the overall practicality of this would be debatable. You would still need to reinforce any connections to components (swing-arm pivots, front end assembly, etc) as simple direct connections to the wood would ultimately fail due to torsional stresses. All this would add up in unnecessary weight - a 4x4 chunk of wood (depending on the variety) can be pretty hefty. You would be much better off going with an all-metal frame.

Just a few things to consider.


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## ewdysar (Jun 15, 2010)

sunworksco said:


> Eric,
> You could use a 3" tube/spine and fill it with high density foam.
> Regards,
> John


Yep, there are plenty of options. Aluminum tubing, Cromoly, wood composite box beam, exotic carbon composite, FRP, riveted frame and skin, etc. It could propbably even be done in cardboard (like one of those engineering school challenges) They'll all work, Darxus gets to pick how much money and effort he wants to invest. My point is that wood isn't inherently worse than the other ideas.

Eric


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## ewdysar (Jun 15, 2010)

michaelplogue said:


> I'm not sure if your goal is for breaking records, or to build something that could be used for daily commutes. If the later, I think you'll have a bit of difficulty making low speed turns with your feet and legs right along side the front wheel like that.
> 
> And as mentioned before, if you plan on driving this in traffic, I think you'll be very uncomfortable being at eye level with the bumper of the cars in front of you - not to mention the fact that you will be very hard to see by other drivers on the road.
> 
> ...


My contributions to this thread have been focused merely on the execution of his proposed design, but I agree that a low slung recumbent for street driving is inherently dangerous. I own a recumbent bike, a Vision SWB (short wheel base) which means that the pedals and chain ring are beyond the front wheel. My butt sits about 18" off the ground and that puts my head right about mid-torso of a person on a typical road bike. I'm about eye to eye with the drivers of most cars. Even then, I remain hyper-vigilant in traffic. There are plenty of low-slung designs (like Darxus') but they are typically relegated to dedicated bike trails and time trials on closed off courses. I would not ride one on a surface shared with regular vehicles.

Eric


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## Duncan (Dec 8, 2008)

Hi Ewdysar

I own a similar recumbent, if/when I rebuild it I will go higher not lower, even at my current height I have had my foot slip out from under me at a stop and I would like to be able to see over the hedges!

People do go lower for competition but I am not at all sure that they are correct to do so,

By going higher you add a small amount of frontal area (the wheels in their pants) but you move further away from the additional drag caused by ground effect and its interference with your aerodynamics

If you make that tube straight or almost straight (lose the bend) and put the wheels below it you can make a similar machine but higher


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## TomA (Mar 26, 2009)

ewdysar said:


> Personally speaking, my homebuilt 17' ocean kayak is thin plywood, regular 'glass and epoxy. It will not rot and won't crack under any conditions that a carbon composite would survive. It is the same weight but stiffer that a molded carbon fiber version of the same, way cheaper too. Could I build a lighter version using more exotic materials or methods, you bet, but the wood composite construction is a very good compromise.
> 
> I'm sure that you know that charcoal briquettes were invented to use the massive volume of wood chip manufacturing waste from the Ford auto plants. My 1400 pound Model T uses a considerable amount of wood in the structure. Sometimes it's easier to use what is availble and easy to work, especially for prototypes...
> 
> Eric


Agreed, but your ocean kayak is thin plywood, not a fat steam-bent timber. I wasn't being critical of _wood_ as a construction material, just this idea of steam bending a huge beam and using it structurally. I stand by my assessment: it will rot and crack, be godawful heavy, and nearly if not outright impossible to form given Darxus' equipment and experience.

Sure, a pressure-formed laminated beam of wood strips and glue _might_ be relatively light and strong (like a custom made curved gluelam beam) and it sure would be cool, but that's about as doable for Darxus as a CF prepreg-covered CNC-milled foam blank that gets baked in an autoclave: great to think about, fun to model on the computer, but actually off the table on attainability and cost.

TomA


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## Hacker (Jul 5, 2010)

Fantasic idea, I am looking at doing something almost identical except I will look at using a current production front end for a leaning trike. Mine will be lifted off the ground a bit more for safety and visability and sitting more vertical for ease of entry and exit. It will be a tube space frame with a fibreglass body and a heater (it gets cold here in winter at 5:30am)

My reasons for leaning are because I love motorbikes, the improved handling and running motorcycle tyres which have a lower drag coefficient.

Tube frame for ease of production and I can comfortably do it myself (engineer by trade) in my garage


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## Hacker (Jul 5, 2010)

Sorry, forgot to add, I am a volunteer fire fighter and I am often up at 2-3am going to a call-out and I have issues starting my rattly noisey old pajero at that time of the morning, and then starting it again to leave for work at 5:30am, this is what sparked the idea to begin with and now it has turned into a work vehicle too.

With a kayak, it is equally supported by water for the whole area that is submerged, but in a recumbent it will be subjected to alot of altering forces from gyroscopics and alot of point loading from mounts etc.

Don't let that stop you and regard everything I say as constructive critisism, if there is anything I can assist with then please just ask.


Damon...


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## Darxus (May 10, 2010)

*4 wheels*





































Harbor Freight screwed up my trailer order. I finally decided to give up and move on. And then I started feeling like the shape I wanted on two wheels was going to be too long to be able to turn reasonably. And being surrounded by 4 wheels would be cozy.

I started with the tire dimensions, wheelbase, overall width, and differential of a 2005 Miata. It looks like I should pretty much be able to bolt a motor right to a diff? And nobody has done that? (I have no measurements on the diff yet.)

Unsure about power requirements as always. I still want to be able to do my commute, 70.4 miles round trip, with a lot of 65mph.

This is with 12x Trojan T-875 8v flooded lead acid batteries (=96v, 384kg (756lbs)), and an ADC K91-4003 8hp 25kg (56lbs) motor. I wanted something bigger than a Mars 0709, but something as big as is intended for a full size car didn't seem appropriate, and this was about what I was looking for. Also, 96v has more convenient options for lead acid battery packs. 

I could also do 16x 12v batteries, or 24x 8v and still get 96v. But that gets heavy. And I could still eventually spend the $10,000 or so on freaking lithium ion, but damn.

82.9cm (32.6") tall. Currently 10cm (3.9") square steel tube frame.

Not sure how much of the Miata suspension I could use. It looks like the extent of the unevenness of the arms is intended for significantly more body roll than I would expect to see at this height?

I'm wondering about interchangeable canopies, with another tall enough for me to sit up and forward enough to fit a passenger. And a telescoping steering column or something.

I think this thing is sexy as hell. If it'll do my commute within 80% discharge, with somewhat reasonable acceleration, and comfortably maintain 65mph.


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## nimblemotors (Oct 1, 2010)

I skimmed this thread, and perhaps it isn't what you looking to do,
but the Bug-E is available as a kit.

www.bugev.net

http://www.youtube.com/watch?v=Aq8F_FY7sqw&feature=related


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## Darxus (May 10, 2010)

*Reduced frontal surface area*



















Spent some time looking at the air tunnels between the driver and wheels in 24 Hours of Le Mans cars, effectively reducing frontal surface area.

Moved batteries in line with wheels.
Wheels and batteries have separate farings from the driver and motor, attached rigidly.
Suspension by single sided swingarms all around.

Haven't worked out the frame details, or added clearance for the swingarms.

Need to keep anti-roll bars in mind. 

I'm thinking, for the front wheels, wheel skirts that open up for turning, roughly like the AeroCivic.

Not the first time I've played with this idea, but I think it's the first time it occurred to me I could use single sided swingarms. From a few years ago, before I switched from povray to blender:


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## Duncan (Dec 8, 2008)

*Re: Reduced frontal surface area*

Hi Darxus

You are suffering under the same misapprehension I was.
For a "non streamlined shape" drag = Drag coefficient x frontal area - TRUE

If you can actually "streamline" your shape drag now becomes proportional to "wetted area"

(Streamlined - means the flow does not separate from the surface - hard to do!) 

The area that the air passes over - by splitting a streamlined shape into three you have trebled the drag!

I found this in am excellent book on aerodynamics when I was helping with the Solar Stealth (We won the "World Championship" in 1999 and 1998)

I was looking for the book for you and I found this web-site
http://www.edocfind.com/en/ebook/Aerodynamic optimization of a solar race car body shape-1.html

I will download some of these for myself!

The Le Mans cars like F1 cars are all about down-force - their drag coefficients are appalling!!


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## Darxus (May 10, 2010)

*Re: Reduced frontal surface area*



Duncan said:


> You are suffering under the same misapprehension I was.
> For a "non streamlined shape" drag = Drag coefficient x frontal area - TRUE
> 
> If you can actually "streamline" your shape drag now becomes proportional to "wetted area"


That does sound familiar. Hard to accept. Some googling didn't help. I'll check out your link. Thanks.

And I think I did actually reduce total surface area with this change.


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## Duncan (Dec 8, 2008)

*Re: Reduced frontal surface area*

Hi Darxus

I can't find any confirmation - I left the book with the Solar Stealth team and I can't find it on Amazon - there is a good looking book on Amazon but its too much money for me right now -$70
There is a paper on the site I referenced but they talk about frontal area as well

I'm going to go away and search the SAE website - I think the book I had was an SAE book


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## Darxus (May 10, 2010)

Can you ask the Solar Stealth team what the book was?


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## Darxus (May 10, 2010)

*MonoTracer*

I've been reading a bunch about the MonoTracer, previously the EcoMobile, particularly the electric model that won its class for the Automotive X Prize. 








Which got me thinking more about using two wheels to minimize road friction, and a battery pack to just handle my commute one way. And taking the pack into work every day to charge. Based on the 123 watt hours per mile they were getting on the highway, and my 56.6 km (35.2 mi) one way commute, I'm coming up with $1,692 and 48 kg (107 lb) of lithium ion cells. I think I like the idea of trap doors for my feet more than outriggers.


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## Duncan (Dec 8, 2008)

Hi Darxus,

The streamlined HPV's are getting over 50mph for the hour record these days,

123whrs/mile at 60 mph would be 123 x 60 = 7.38Kwhrs for one hour - 7.38Kw - far far more than a person can develop for an hour

If you built your two wheeler light 1Kw should be enough power and that should drop your battery weight and cost down by a factor of seven! 

I would build it higher as well
Visibility - see and be seen
Stability - its counterintuitive but a higher center of gravity is more stable in a two wheeler'

Stopping - if you are very low when you stop and put your foot down its difficult to hold yourself
If you are higher your leg is more under you and easier to hold
Also if your leg is not under you your foot can slip easier!


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## Darxus (May 10, 2010)

Duncan said:


> The streamlined HPV's are getting over 50mph for the hour record these days,


Last night I was looking through the posts to this thread, and saw where you last brought that up nine months ago. It's certainly interesting, but: 

I don't think that the power generated by a human over an hour would give me appropriate acceleration for highway use. Exactly how long does it take them to get up to 50mph?
Wind resistance is exponential, and I want to go 65mph, not 50. 
And my calculation was 123 watt hours per mile * 35.2 miles = 4.3 kilowatt hours.

And I need more weight than they do. I probably weigh twice as much as those people do. And I need suspension, and tires and wheels that will last longer than a single run in ideal conditions.

But it would be nice if I could go round trip, 70.4 miles, on one charge.

I understand the reasons for building it taller, and I realize most people would probably prefer it. I would certainly be more visible, and I've done enough riding to vividly understand the improvement in stability (hit a patch of sand while leaned over on my CBR1100XX, and was very happy to have that inertia to keep me up). And yes, completely laying down would give me a mechanical disadvantage for keeping the thing up with my feet.


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## TomA (Mar 26, 2009)

*Re: 4 wheels*



Darxus said:


> I like this idea better than the sausage bikes. Mickey Thompson did, too:
> 
> 
> 
> ...


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## Darxus (May 10, 2010)

*Re: 4 wheels*



TomA said:


> I like this idea better than the sausage bikes. Mickey Thompson did, too:


But doubling the wheels probably at least doubles drag, both against air and the road. Which means thousands of dollars more in cost of lithium batteries for the same range. And doubling the weight of the batteries, which means needing more batteries, which means needing more batteries. 

If I were more sure of getting something to work, or more comfortable spending $10,000 on batteries, I might spend more time on four wheeled ideas.

The E-Tracer has a 150 kilowatt hour lithium pack, and a range of about 100 miles. Tha'ts about about $7,812 at the prices I'm finding. And that's two wheels. With an A/C motor, which I believe is more efficient. And on a flat oval race track. My commute has hills.

And I think it would be interesting if I could demonstrate the possibility of making a vehicle that'll go some useful distance at 65mph for ~$3,000 in parts plus a bunch of labor. With a roof.

I'm aware how much help it takes to ride one of the HPV record bikes. Foot holes will help. 

Yes, four wheels would be more convenient. But why do you say it "could have far greater range"? With the same cost in batteries? Anything could have far greater range with far more spent on batteries.

Lately I've been wondering a lot if I should just use a motorcycle engine. It would be a lot cheaper. SCCA DSR and Formula SAE provide lots of examples of four wheeled vehicles with mid/rear placed motorcycle engines.


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## TomA (Mar 26, 2009)

I wasn't suggesting a four wheeler could go farther on the same pack.

What I was referring to is the overall package of payload, weight and drag favoring a small 3 or 4 wheeler over a 2 wheeler, because I think you can safely pack more batteries into it as a percentage of total mass.

If your pack size is that limited, then yeah, the smaller the vehicle the better.

Actually, on a budget of $3k, your are much better off abandoning electric drive altogether. Take another look Dave Malewicki's California Commuter. Its pretty much in the envelope of what you've been trying to do, and you're going to work awfully hard to beat its (World Record) efficiency- even now, over 30 years later. You might also actually be able to build it for $3k, with a motorcycle engine, if you can weld and 'glass.

Interestingly enough, an EV version of the CC is apparently in or nearing service:

http://www.canosoarus.com/03CalifCommuter/CalCom05.htm

TomA


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## Darxus (May 10, 2010)

I don't think pack size is significantly limited by only having two wheels. How much does a Corvette V8 weigh? The Boss Hoss uses it. 575 pounds. That's ~23.9 killowatt hours of lithium batteries.

I don't have a specific budget. Just discomfort spending so much money on something that might not work out. 

The California Commuter is pretty cool. But if I built something with a motorcycle engine, I'd probably end up using a stock superbike engine. 

Unfortunately the page for the electric version of the California Commuter has been at "As yet, the conversion is not finished." for at least 13 years: http://replay.waybackmachine.org/19...w.canosoarus.com/03CalifCommuter/CalCom05.htm
That thing sure is similar to Electrathon cars.


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## TomA (Mar 26, 2009)

The CC is bigger, stronger and a lot more roadable than an electrathon car. I can't thing of one that could safely pull into most driveways, let alone leave the road surface.

I suppose you can make a motorcycle as heavy as you want, but I'm not sure a relatively heavy bike is more efficient than a lightweight trike using the same powertrain and pack. At a certain point you're using huge tires, dampers and suspension components on a touring-class motorcycle, and you have to use a very stout frame to control those road inputs (because they are all coming through two points of suspension and not three or four) and to carry that heavy pack. There are also packaging problems that are significantly easier to deal with in a three or four wheeler. 

Its a problem of diminishing returns, which is why I say that a three or four wheeler is a better way to package the whole deal.

The Boss Hoss is a great example of this. With that Chevy V8, it gets 13mpg city, 18mpg highway. My 1994 Caprice wagon, which weighs 4600lbs and has almost the same engine, gets about 17mpg city and an astounding 24mpg on the highway, carrying a load of people and stuff. Its just a better package. 

In that light, if you're going to get a superbike engine, you're going to use a lot of fuel, relatively speaking.


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## Darxus (May 10, 2010)

TomA, I suspect your better mileage has less to do with better packaging and more to do with better gearing. 









3.2 volts x 22 cells = pack voltage of 70.4, more appropriate for a 72 volt motor. Or would it be better to do 23 cells = 73.6 volts?

With 22 60 Ah cells, that's 34.3 miles = 97.6% of my way to work, at the E-Tracer's efficiency.


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## TomA (Mar 26, 2009)

Darxus said:


> TomA, I suspect your better mileage has less to do with better packaging and more to do with better gearing.


Agreed- also a milder camshaft, lock-up torque converter, better match between powerband and gearsets/final drive and better fuel management, too. So what? Even if that's 150% of the efficiency _difference,_ the wagon can still carry 8 people around in climate controlled comfort, at triple the weight, for around the same fuel consumption. That is all packaging, or rather, the especially poor packaging the Boss Hoss offers as a huge motorcycle. 



Darxus said:


> 3.2 volts x 22 cells = pack voltage of 70.4, more appropriate for a 72 volt motor. Or would it be better to do 23 cells = 73.6 volts?


In service, the cells are going to sag below 3 volts, and even 25 of them wouldn't be too much for a 72 volt motor at all. The more presing question is what is the upper voltage limit of the controller you want to use? Then you divide that by your maximum per cell voltage, something like 3.5-3.85, in order to see how many cells you can use with it. The prismatic cells have a resting voltage around 3.35, so if you let them sit for a while after you charge and before you power up the controller, you should be fine with a cell count using the 3.5-3.85 calculation.


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## toddshotrods (Feb 10, 2009)

TomA said:


> Agreed- also a milder camshaft, lock-up torque converter, better match between powerband and gearsets/final drive and better fuel management, too. So what? Even if that's 150% of the efficiency _difference,_ the wagon can still carry 8 people around in climate controlled comfort, at triple the weight, for around the same fuel consumption. That is all packaging, or rather, the especially poor packaging the Boss Hoss offers as a huge motorcycle...


I am impressed with the efficiency of your wagon Tom (and that of a lot of the big modern V8 cars in general) but you're kind of stacking the deck using the Boss Hoss. It was purposely designed for thrills. If someone took that same concept, but designed for efficiency from the start, I suspect it would have phenomenal numbers as a result. Use a modern GM 5.3 displacement-on-demand V8, with the full factory control systems. Gear it for efficiency, rather than impressive smoky burnouts, etc.

I get your point but the comparison was skewed in favor of your argument. The bike was never designed for efficiency - just smiles.


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## TomA (Mar 26, 2009)

Well, sort of, Todd.

My point is that the bike is harder to package efficiently as it gets larger. Its just that simple. 

My V8 is not an LS1, but the very same pushrod LT1 in the Boss Hoss. Due to PACKAGING problems, the motorcycle can't support the efficient transmission that makes the car work so well. The EFI Boss Hoss is rated at 20mpg/25mpg, so that's an apples-apples comparison. Don't slide the bike's motor past the car's to make your point, either. Even with all the improvements you're talking about, though, and a full fairing you can't see behind or put a foot out of to keep from falling over, the bike is going to get, what, 35mpg?

That's a terribly inefficient compromise for the rated load. I'm not saying it isn't a performance machine or cool or desirable or any of that. I'm saying its inefficient, and not primarily because its sporty. The primary reason is that the scale of the whole package is outside the natural design efficiency envelope of a two-wheeler, which is optimal in a bicycle and goes down from there. 

By the time you get over 1000lbs, you are spending so much energy keeping the wheels located, the components cradled and the power delivered that you'd be better off (more efficient) moving that 1000lbs around with a more appropriate design.

But I totally agree with you. The Boss Hoss is a dramatic example, skewed worse by its thirsty motor. My wagon, of course, is the all-time champion of efficiency with the same motor, having been continuously co-developed with it for just that purpose over more than 50 years. Hell yes, its an unfair comparison, but that doesn't invalidate the underlying problem.

Gotta love those wagons, though. Just bought my (super clean) 1994 Caprice out of an old man's garage with 103k on it, after selling my 1992 due to ugliness (dents, rust) that made it unwelcome (by the wife) in the driveway. 211k miles on that one, and ran like new. Indestructible cars...

TomA


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## Darxus (May 10, 2010)

TomA said:


> By the time you get over 1000lbs, you are spending so much energy keeping the wheels located, the components cradled and the power delivered that you'd be better off (more efficient) moving that 1000lbs around with a more appropriate design.


That's some serious arbitrary bullshit.

The winner of the tandem seating class of the automotive X Prize was 1260 pounds and had two wheels (The E-Tracer / X-Tracer / electric MonoTracer). 

Competitors in the tandem class:
Edison2: 4 wheels.
FVT Racing: 3 wheels.
Spira: 3 wheels.
Tango: 4 wheels.

The only one on two wheels won.


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## TomA (Mar 26, 2009)

Darxus said:


> That's some serious arbitrary bullshit.
> 
> The winner of the tandem seating class of the automotive X Prize was 1260 pounds and had two wheels (The E-Tracer / X-Tracer / electric MonoTracer).
> 
> ...


Fair enough. That's a fascinating design. Far beyond the home builder, I think, but proves your concept.

As a package, its little more than a test rig. That's a problem with most all of the X-Prize finalists. For production, the outriggers would need to be strong and fast enough to catch a low speed tipover, which there's currently no provision for at all. Hence the training wheels, (which also don't work,) and the required ground crew of handlers. 

http://green.autoblog.com/2010/11/10/la-times-writer-tries-to-test-drive-peraves-e-tracer-drops-it/

Cool toy, though. Reminds me of a Pulse without the outriggers. Something between these two designs, with retractable wheels in stout outriggers, might actually be practical. I stand corrected on the ultimate size and basic efficiency of a motorcycle, except that low speed stability and recovery become really serious matters in something this size. 

Bias disclosed: I don't like big motorcycles. I like tiny cars. 

At any rate, thanks for the info.

TomA


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## Darxus (May 10, 2010)

TomA said:


> As a package, its little more than a test rig.


Stop making stuff up 

'From 1988 to 2004, there were 95 Ecomobiles made (the “Ecomobile” is the predecessor to the MonoTracer®). In 2008 and 2009, there were 18 MonoTracers, and 2 “E-Tracers” made (the “E-Tracer” is an all-electric version of the MonoTracer®). The company projects that in 2010, they will make 36 MonoTracers and 2 E-Tracers.'
- http://www.21stcenturymotoring.com/FAQs.html

The only thing new about it is the conversion to electric.



TomA said:


> http://green.autoblog.com/2010/11/10/la-times-writer-tries-to-test-drive-peraves-e-tracer-drops-it/


Yeah, switching from outriggers down, steering like a car, to outriggers up, steering like a bike (which means turning the handlebars in the opposite direction) is apparently hard to get right the first time. And the vehicle is challenging to pilot in general. No argument there. 

But you should see the video of somebody under control laying the thing down on a retracted outrigger, coming to a complete stop, and then standing it back up with the outriggers remaining retracted.

I occasionally contemplate foot controlled outriggers. A long travel foot pedal for each side providing a lot of leverage, and speed similar to putting your foot down directly. With motorcycle type controls and a direct electric drive train, the left foot is freed from the shifter, and the right foot brake pedal can be moved to replace the left hand clutch lever. I also wonder about applying that concept to a full tilting 3 or 4 wheel vehicle, except adjusting the tilt instead of deploying outriggers.


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## Darxus (May 10, 2010)

And... no space for front suspension travel. I think I'm more willing to do a single sided swingarm, or as Todd suggested, a pair of single sided swingarms with an automotive type knuckle. But I don't think a wheel as small and light as I'd like exists made for a single sided swingarm (so the knuckle could be centered horizontally).

It would be nice if this didn't end up being a theoretical design exercise forever.


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## Darxus (May 10, 2010)

I think I solved my steering (height) problems.

This is an incomplete diagram of "focusing link" steering, apparently popular with LSR (land speed record) streamliners (it's lacking the shocks to keep the front end from flopping up):







from http://www.rotaryeng.net/roadable.html
It seems to basically have the advantages of hub center steering, without the complexity and corresponding cost. So it blows my mind that there is so little related information I could find on the web. At least with the name "focusing link".

The current 50cc LSR holder by Buddfab (233kph (145mph)) uses something similar that I think is better for my purposes:







from http://www.buddfab.net/buildphotos.html







from http://www.motorcycle-usa.com/287/1518/Motorcycle-Article/Salt-Addiction-Buddfab-Streamliner.aspx

It's a leading link fork, which might be the second most common type of motorcycle front suspension, except instead of the normal head with a pair of circular bearings at the top, it has a single spherical bearing (heim joint?), and the lower end of the fork is supported by a pair of links, creating a virtual pivot where those links would intersect if they were longer.










Orange is the fork (attached by heim joint at top center). 
Yellow is coil-overs. 
Blue is the swingarm (from leading link suspension). 
Purple is the links supporting the bottom of the forks, with heim joints at both ends.

This gives me 8cm (3.1") of travel along the axis of the coil-overs without needing to raise the body, or do something silly like a trap door for the steering head to pop through.


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## Duncan (Dec 8, 2008)

Hi,

Just looking at your energy needs 

http://www.diyelectriccar.com/forum...rcycle-build-need-help-suggestions-56252.html


energy consumption per mile..
Agni motored Aprilia sportsbike, 130kg. best 70wh/m worst 145 wh/m

Dual Agni motored TTX02 175kg. Best 100 wh/m worst 300wh/m (well, it is a race bike)

These are non faired bikes - terrible drag coeficients


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## Darxus (May 10, 2010)

Duncan said:


> energy consumption per mile..
> Agni motored Aprilia sportsbike, 130kg. best 70wh/m worst 145 wh/m


Thanks, but that's pretty useless without knowing the speeds.


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## Duncan (Dec 8, 2008)

They are sports bikes - got to be at least 10mph Duhh


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## Darxus (May 10, 2010)

I was thinking that spending $3,000 (in parts) to prove an electric commuter could be built that nobody but me would be crazy enough to use might be less interesting than spending $6,000 on one that a few more people would be crazy enough to use, so I spent more time on a four wheeled model. Additional cost being battery, controller, and motor to push more air and rolling resistance.

I like tandem seating. I previously had difficulty coming up with a four wheeled tandem seating arrangement that I liked, so I worked on side by side, making use of a Kamm tail (you can lop a teardrop off after tapering down to 50% of its maximum width and still get most of the benefit - stable vortexes fill in the tail):









Then I made another attempt at tandem:









I'd really like to see more info about total surface area vs. frontal surface area, because I could definitely reduce the total surface area here by raising the surface between the people and the tires up to the height of the top of the fenders. But I really find it hard to believe that pushing that much more air would be good. Vertically accelerating that air out of the way takes energy. And I have difficulty believing air is that sticky.

I think this windshield would have to be polycarbonate. 

I don't think a Kamm tail would work here, but... I'd really like to get my hands on a translation of Wunibald Kamm's book.

Clearly, I'm never going to stop changing my mind. If I'm ever going to build something, I'm going to have to accept that, pick a design, stop screwing with it, and build it.

*1986* Oldsmobile Aerotech, longtail. Set a bunch of records. This is what an aerodynamic car looks like without a Kamm tail.


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## Darxus (May 10, 2010)

*Minimizing wetted area*

Frontal area:









Frontal area after the most obvious optimization for minimum total surface (wetted) area:









Here, as I understand it, Duncan says the second one should have lower wind resistance:



Duncan said:


> You are suffering under the same misapprehension I was.
> For a "non streamlined shape" drag = Drag coefficient x frontal area - TRUE
> 
> If you can actually "streamline" your shape drag now becomes proportional to "wetted area"


He's not the only one I've seen say this. I find it hard to believe.


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## TomA (Mar 26, 2009)

Darxus said:


> I was thinking that spending $3,000 (in parts) to prove an electric commuter could be built that nobody but me would be crazy enough to use might be less interesting than spending $6,000 on one that a few more people would be crazy enough to use, so I spent more time on a four wheeled model.


All well and good, but the four wheeler is going to run you up against all kinds of regulatory trouble. You have DOT (safety, lighting and general configuration) and EPA (emissions) requirements to meet. Just because its electric doesn't mean you won't have to deal with EPA regs in some fashion. It will also very likely be uninsurable.

The regs applicable are to the year of mfr of the donor vehicle. No donor vehicle or purchased kit? That's such an uphill battle as to not be worth the trouble. Practically speaking, you must have a donor or kit base car. About the only practical way I know of to license something like a scratch-built car is to buy the title and VIN of something _really_ old, like a Model T Ford or '50s Fiat or something. There are services that have things like this for sale. Then, at least, you can insure it.

Cars built before 1966 have no EPA requirements applicable. I'm not sure when the FMVSSs kick in, but there are very few, if any DOT requirements for prewar cars. There _are_ minimum configuration standards, like how many lights at what height, bumpers, brakes, etc. in every state that apply to all vehicles no matter when manufactured, but with something titled as a 1926 Maxwell you may be exempt from a lot of that in some places. Its a crapshoot state-to-state and also depends who you run into at the DMV. Big-time uncertainty, there.

Bottom line? A scratch-built four-wheeler will probably be a devil of a thing to register and insure, in any jurisdiction. That's why so many home-builts and kits are 3-wheelers (motorcycle rules; much easier to deal with everywhere,) and virtually all of them are either registered on a donor VIN and/or an MSO (Manufacturer's Statement of Origin) from the kit car company. Even on 3 wheels, registering a completely scratch-built vehicle can be a royal PITA. On four, its an order of magnitude more difficult, or two...

Just a heads-up,

TomA


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## Darxus (May 10, 2010)

TomA said:


> All well and good, but the four wheeler is going to run you up against all kinds of regulatory trouble.


I'm curious how much of that applies in New Hampshire. My car is legally uninsured. But yes, I know 4 wheels has more requirements than 3, due to qualifying as a car instead of a motorcycle.

I know laws can be dumb, but I'm really not worried about emissions requirements on an all electric vehicle.


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## Darxus (May 10, 2010)

800x600 450 frame video.


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## Duncan (Dec 8, 2008)

*Re: Minimizing wetted area*

Hi Darxus

Ref your two frontal views
The "fatter" one would also need a longer "tail" for the fatter bits - to allow the air to flow off it

Whereas the thinner one could have a shorter tail where it is thinner

Would probably mean the lower frontal area would have less wetted area as well

This gets complex - besides I'm not sure that a "streamlined" shape would be practicable for a road vehicle

On a separate topic - I thought it was easy to get a scratch built machine licensed in the USA?


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## toddshotrods (Feb 10, 2009)

*Re: Minimizing wetted area*



Duncan said:


> ...On a separate topic - I thought it was easy to get a scratch built machine licensed in the USA?


Depends on what state you live in. Ohio, is a breeze. Have proof of where you got pretty much _everything_, meet the basic safety requirements (lights, horn, wipers, seat belts, etc), go through an inspection with the Ohio State Highway Patrol, pay up, and drive! Ohio has no emissions checks, no annual safety inspections, etc. PA is also pretty simple, but has annual safety and emissions inspections. For classic, and I think specialty, cars you can get a waiver on those, but it limits the amount of miles you can drive.

As far as insurance, even some of the major companies will provide liability coverage for whatever is legal in your state. They'll also often provide "stated" or "declared" value comprehensive coverage, but I wouldn't count on getting much in return when something happens. The specialty companies like Barrett Jackson, Grundy, etc, will insurance your baby and pay up in full if something happens (and provide liability so you can drive it), but they'll usually limit the amount of miles you drive and not allow you to use it for daily commuting. It has to be a recreational toy that you use for enjoyment with them.

The best advice is don't build anything, and don't buy anything, until you know what's required in your state. Don't go off hearsay, or what Uncle Bob did fifty years ago either. Go to the DMV or BMV and find out what's required. Get the paperwork and ask every question you can think of. I can't imagine anything worse than building your dream vehicle and then finding out you can't ever use it!  I originally started building the Inhaler withough knowing what was required in Ohio. I lived on the border of OH/PA then, and was going off what some people in PA who had been through the process told me. When I finally talked to the OSHP I was freaked out because Ohio requires more proof, and I didn't have it. In PA (at least back then) you send in receipts for the major stuff with three pictures, wait, wait, wait, and finally get documents in the mail. Then you go through the normal inspection processes there, where they verify everything and give you inspection stickers, then you can get you r plates - something like that. Worse case scenario in Ohio was they could confiscate my project at the inspection, if they had doubts about where I got the parts! I got rid of a bunch of stuff I couldn't verify, and started collecting receipts like stamps.  The good thing about Ohio is everything is done right there-right now. Go through live inspection, get papers, go get plates, call insurance, drive...


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## TomA (Mar 26, 2009)

Very interesting, Todd.

Do you start with a pile of parts and receipts, and no title, and wind up with an assigned VIN, a title for it, and a make and model year? Without a standard make and model year, most insurance companies are going to have a hard time writing a policy. Also, is there some kit/specialty/home-built/hobby exemption that allows you to have a "2011 Toddmoco Inhaler" and not meet the 2011 FMVSS? This is all quite astonishing, coming from my experience in NY, IL and CA.

Maybe the secret is to sell you my car, trailer it to OH, pay you to VIN, title and license it, and then have you sell it back to me. I'll keep you posted...

Once a vehicle is titled and registered in any state, its very easy to transfer everything to another state. That's how lost titles are "washed" in places like Alabama or wherever they're really lax on the requirements. 

TomA


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## toddshotrods (Feb 10, 2009)

TomA said:


> ...Do you start with a pile of parts and receipts, and no title, and wind up with an assigned VIN, a title for it, and a make and model year?...
> 
> ...Also, is there some kit/specialty/home-built/hobby exemption that allows you to have a "2011 Toddmoco Inhaler" and not meet the 2011 FMVSS?...


That's pretty much it Tom. I think it would indeed be titled as a 2011 Specialty Vehicle (or something like that), but without the emissions and crash requirements. I made it very clear that I was indeed taking a bunch of raw materials and miscellaneous parts and building a vehicle from scratch. No matter how I worded it, they basically just repeated make sure you have receipts - I can't stress how much that was emphasized.

I go to the OSHP inspection station with my vehicle and paperwork, pass (hopefully) the inspection, and get a VIN, and paperwork for the title. I take that to the BMV get my title and plates. Here in Columbus, the two distinct braches of BMV (one where they do titles and one where they do registration) are normally located a few doors from each other in little plazas. You can literally walk in and get the title in a matter of minutes (from a sell/transfer, to a duplicate, etc), walk a few doors down and get the plates. I just did that for my new-to-me daily driver last week.

This is a part of the reason I am still in Ohio, even though I hate winter with a passion. It is very friendly to custom automotive enthusiasts. My Honda Accord-based project has so much composite work that people don't know what type of car I started with. I still have it titled as a 1991 Honda Accord, and the few times I've been stopped (for bulbs out, etc) I think the real reason was for the officer to get a better look!  They ask a bunch of questions about how I did it, and where I'm going with it, say have a nice day/night, and watch the crazy car drive away!

Just before the recession hit, Ohio had a SEMA-sponsored bill on the table that would allow us to register scratch-built "antique" specialty cars as the model they most resemble. In other words, the Inhaler would actually be titled as a 1923 Ford Model T Pickup - not a specialty vehicle! I'm praying they get the budget sorted out and get it up for vote by the time I'm ready for registration.

Sorry for the hijack Darxus, but this information may all be useful to you...


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## Darxus (May 10, 2010)

toddshotrods said:


> Sorry for the hijack Darxus, but this information may all be useful to you...


Not at all, I was specifically hoping you would respond to this subject. Thanks. What you said is about what I was expecting - I know to keep _all_ receipts.

And yes, this kind of thing is part of why I live in NH.
http://www.freestateproject.com/ - Warning: Politics.


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## Third_degree (Jan 11, 2012)

Hello Darxus,

I'm sure you are aware of the NSU "flying hammock" 2-wheeled streamliners:

http://hedonia.net/art/dalniks.htm

They have nearly perfect aero shapes. Only word of caution as I watch your pursuit of reduced frontal area, you should know that the designer (Baumm), died in his creation as he tested on the "ring" in Germany. He sat so low that he was unable to see well enough as he crested a eidge and drove straight into a tree, as he could not spot the turn from his completely laid back head as low as possible posture.

Also, looking at some of your shapes (And as an aero buff), you could use sharper trailing edges, and reduce your departure angles to no steeper than 15 degrees (10 degrees to give some margin) in order to reuce separation.

FYI, I'm creating my own designs as well, and its cool to see we have had some similar ideas (Pod Car) for example.

I'm creating a tilting trike. Just to make it harder...


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## Duncan (Dec 8, 2008)

Third_degree said:


> Hello Darxus,
> 
> I'm sure you are aware of the NSU "flying hammock" 2-wheeled streamliners:
> 
> ...


Hi Third

I like the tilting trike idea - especially as it eliminates the need to go low - you can end up with low drag and a nice high eyeline


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## Darxus (May 10, 2010)

Mmm, thread necro.

I guess this is a good time to tell you folks where my mind has gone. A big part of my motivation to build an electric vehicle is Peak Oil. Concern that the global oil supply will deminish, oil will become more expensive, and everything that depends on it will go away. Including food. And other forms of energy will be at least very difficult to replace the oil with. 

So, electric car + solar arrays seemed nice. But the low energy density of even lithium cells, and cost, relative to fossil fuels, really wore on me, and I ended up feeling like there's no point if I won't be able to get another set of cells for replacement every few years. Nickle iron seems to be the best battery chemistry for long life, but HEAVY (significantly lower energy density). Unless you can tell me where to dig up lithium and how to make it into a battery in my home.

Did you guys know there was a time and a place where it was _common_ to run cars on wood gas? I think Eastern Europe in the vicinity of World War II? A gasoline engine is relatively easy to convert. Also, apparently you can run a diesel engine on rendered pig fat. I learned these things from The Colony, a "reality" TV show about surviving an apocalypse. Certainly not perfect, but it had some neat ideas.

But building something to commute in that lacks the excessive cumbersomeness of cars, while having the roof and stability that motorcycles lack, still sounds fun. And something based on a gasoline engine seems likely to be cheapest / most practical. I think a Suzuki TL1000 / SV1000 / V-Strom 1000 engine best suites my taste. Built similar to a Formula SAE car.

Yesterday I came across two photos of an incredibly sexy Formula Vee car, a race series based heavily on classic Volkswagen Beetles - same engine, suspension, wheels, etc. Bill Noble's Caracal D:

















I think it was the only enclosed Formula Vee - being the first, and having it outlawed shortly after. Beetles have incredibly sexy guts.



Third_degree said:


> Hello Darxus,
> 
> I'm sure you are aware of the NSU "flying hammock" 2-wheeled streamliners:
> 
> ...


Yup.


Third_degree said:


> Only word of caution as I watch your pursuit of reduced frontal area, you should know that the designer (Baumm), died in his creation as he tested on the "ring" in Germany. He sat so low that he was unable to see well enough as he crested a eidge and drove straight into a tree, as he could not spot the turn from his completely laid back head as low as possible posture.


That sounds fine to me 
Although I wouldn't limit my visibility that much, for use on the street.


Third_degree said:


> Also, looking at some of your shapes (And as an aero buff), you could use sharper trailing edges, and reduce your departure angles to no steeper than 15 degrees (10 degrees to give some margin) in order to reuce separation.


Thanks. I suspected that was true. It's an annoying problem, not wanting excessively long tails, and not sure exactly how Kamm tails work on, say, a cylinder, instead of a typical car shape. Having specific angles to work toward seems helpful. I want some computational fluid dynamics.


Third_degree said:


> FYI, I'm creating my own designs as well, and its cool to see we have had some similar ideas (Pod Car) for example.
> 
> I'm creating a tilting trike. Just to make it harder...


Cool. It is neat how related ideas converge. Do let us know how it goes. There is a relevant yahoo group for people building tilting vehicles: http://groups.yahoo.com/group/tilting
I've thought about tilting ideas a bunch, but never came up with anything I really liked. It seems often the tilting travel and suspension travel are combined, resulting in:
1) When at maximum lean, you have no suspension travel.
2) When leaned over, suspension movement is perpendicular to the road, instead of parallel to the lean angle (as in a motorcycle). I don't know of any actuall information on which is best.


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## Third_degree (Jan 11, 2012)

Good Stuff (Formula V)

Agreed as to motorcycle power. I found out about the Auto X-prize about 1 month before entry was due, so I never entered. However I did a lot of work on analysis, and math, and came to a surprising conclusion:

If you want to save the planet. Electric and hybrid dont work. As you point out energy density of gasoline is so dramatically ahead of battery power is the major issue.... followed by coal and oil being used to make most electricity, followed by charging eff of the batteries, and the only 30% recovery of braking energy of batery electric systems, and the extreme weight of the batteries.

Than when you can see the amazing speed that the hammock car got out of such tiny engines....

So my entry would have been basically a hammock car (shape, low rolling resistance for 2 wheels, etc) with tandem seating for 2. A small (250cc) motorcycle engine converted to direct injection, and turbocharged.

Issue ends up being the outriggers, etc. Thats why I went toward tilting trike... that has its own issues (Max lean, free lean? Electronic control?, do you switch between countersteer and conventional steer when locked upright, or at maximum lean?.... etc etc)

I have actually come up with solutions (And your suspension concern as well). 

I'll show when I have the CAD further along. My completed CAD design is a tadpol performance trike.... basically a T-rex with tandem seating (Aero concerns again) and a monocoque chassis. Even started to build it. But really liked the performance potential of my latest idea better, so have changed directions....

P.S....Do you live in NH?


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## Third_degree (Jan 11, 2012)

Oh.... incomplete response:

Kamm Tail:

The answer is the Aptera. They switch from bullet shape to a flat departure / Kamm type tail. Also the Olds Aerotech car from the 90's I think.... has a very good trailing shape. (See the long tail at the bottom)

http://www.carstyling.ru/ru/car/1987_oldsmobile_aerotech/

As to not making it too long... you are correct, you don't have to come to a complete point at the end. You can cut it off flat. But you can't have rounded trailing edges. In fact it is better if you cut it off. You see there is a balance between the drag associated between a void (separation) at a truncated shape, and the skin friction associated with a very long design. For examples look at the original VW 1 liter car. They just make a sharp cut at the tail.

http://www.treehugger.com/cars/volk...d-edition-of-1-liter-car-282-mpg-in-2010.html

If you round the trailing edges, the air tries to conform to the surface, and fails, making a vortex.

Sharp edges allow the air to break free cleanly.

In the case of the Aptera, they use the low pressure created at the cut-off tail to pull air through from internal vents, etc.


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## Third_degree (Jan 11, 2012)

Duncan,

Sorry for slow response (Trip to China)

Yes, the higher sight-line is part of what I wanted out of the tilting trike. Plus you have to go higher in order to have enough lean (45 - 50 degrees). My conventional tadpole trike is very low. I;ll show some shots from that one.


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## Third_degree (Jan 11, 2012)

You will notice that my tadpole is NOT a perfect aero shape. This design allowed simplified monocoque chassis construction (Aluminum honeycomb)....

I also thought it looked cool. Suspension design is dead on, with almost no change in roll center and very long arms made possible by the tandem seating. Wheelbase ends up a bit long (105")

Again aero is much better than a T-rex, but I have gone for style over reduced cross section and nice clean shapes.

My tilting trike is tandem seating, with a design goal of optimized aero, with reduced frontal area....

Thats why the Pod car makes a lot of sense (A perfect aero shape with 2 wheels to hold batteries, and another pod to hold t-people....

Keep verything the hight of the tires as much possible.... pretty cool.

My tilting trike does not do that (Again I decided against electric).... but the concept is very well based in my opinion...


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## John (Sep 11, 2007)

Third_degree said:


> If you want to save the planet. Electric and hybrid dont work. As you point out energy density of gasoline is so dramatically ahead of battery power is the major issue.... followed by coal and oil being used to make most electricity, followed by charging eff of the batteries, and the only 30% recovery of braking energy of batery electric systems, and the extreme weight of the batteries.


If you’re talking about complete solutions that tick all the boxes then yes electric cars aren’t going to stop our personal transportation from putting greenhouse gasses in the atmosphere not many solutions if any will. The problem then becomes how to minimize rather than eliminate emissions. Hybridization can reduce consumption and hence emissions for any given transportation need so it is difficult to say that it doesn’t work. The problem with battery electric hybrids is the power density of the battery to perform functions like regenerative braking. When a car brakes to a stop from say 100 km/h it can do this in as little as 2 seconds yet our batteries will likely have a power density of C3 meaning the quickest they can be charged or discharged is about 20 minutes or about 1/600th the rate we need if it was optimally sized for the regenerative function of a 100 km/h stop. So we have to fit a battery 600 times bigger than we need to perform this function in order to get sufficient power handling capacity. If we could find a battery with a C60 power density we could hybridize our vehicle with a battery 1/20th the size to add a simple regenerative function. This is an over simplification but you get the idea. As time goes by the power density of hybrid batteries is improving and consequently they are getting smaller, lighter, and cheaper and the hybridization penalty in weight and cost is shrinking. The other thing optimally sizing the battery would do is subject it to many more and deeper cycling of the battery which would be detrimental to its durability. People have experimented with flywheels and hydraulic accumulator as alternative energy storage systems for hybrids in the past.

One of the things that became evident to me when looking into electric powered model aircraft is that when considering weight you need to consider the weight of the entire propulsion system. Even though batteries have an energy density that is a tiny fraction of gasoline, electric motors typically weigh much less than internal combustion engines and have an efficiency that is typically four times the ICE. Electric motors also typically can use a much simplified transmissions compared to ICE’s due to their much wider torque band, torque from stopped, and reversibility. This could result in a much reduced overall drive train weight to offset the increased energy storage weight. In the USA about 50% of your power comes from coal. In NZ it is much less. I have come to accept that there is some validity in the long tail pipe argument but this is very much dependant on your local power generation mix.


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## Third_degree (Jan 11, 2012)

Great response John... Very good points. I'd like to flesh out my take a bit better:

Braking energy. Most efficient way to capture is to not change state. In other words don't covert from mechanical energy to electrical and back to mechanical again as done currently. Instead, use hydraulics and CF accumulator tanks. Energy density of energy storage is poor, but efficiency is much higher. You can recover 80 percent of breaking energy as opposed to 30% for electromotive. Goal is to store only enough energy to help with starts up to no more than 30 mph. So hybrid yes.... electric hybrids perhaps not.

50% energy is used on aero.... so truly streamline the vehicles, with greatly reduced frontal areas. so for a 4 passenger vehicle, take a basic GM EV1 shape, but stagger the seating to reduce cross section. That will solve the energy at speed, such that a very small, light engine is all that is needed for top speed (NSU achieved 212 MPH with 40 HP).

Now make the car very light, to reduce stop and go energy requirements, and use the Ohlins 2wd system found on 2wd enduro bikes as your energy recovery for breaking stored in a 10 gallon CF tank that forms the backbone of the chassis (Strength needed to contain 5K psi greatly exceeds dynamic forces).

Edison2, has performed most of this.... just add hydraulic energy storage, direct injection, and cross sectional reduction (and hopefuly some style.... there car is very ugly), and you are so dramatically more efficient than a prius and your there.

Freedom motors also makes some tiny rotary engines that are extremely light, small and efficient. Much better than wankle's rotaries due to the size. But the power is only good enough if the cars shape and weight are efficient enough.

All that being said I am very very hopeful for electric. Love the motor size as you point out. And hopeful for battery or supercap improvements in the future. But we have to factor in the extreme energy requirements to MAKE a battery. The mining needed to get lithium, and other chemicals to make current batteries is far higher than drilling operations for oil. And finally disposal of the batteries at end of life.


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## DavidDymaxion (Dec 1, 2008)

Can you provide a reference for a hydraulic accumulator that is 80% efficient? I thought any compression system lost a lot of energy to heat.

In any case, you can't recover anywhere near 80% in a practical regen system, even if the regen system itself were 100% efficient -- around 30% is the practical max due to unrecoverable losses like rolling resistance and aero drag. (BTW I checked this in my own electric car, regen down a hill was about 1/3 the power (Volts*Amps) as to climb the hill, that was the biggest ratio I was able to measure.) Note measuring Volts and Amps directly was a better number than the actually usable stored energy due to electrical inefficiencies.


Third_degree said:


> Great response John... Very good points. I'd like to flesh out my take a bit better:
> 
> Braking energy. Most efficient way to capture is to not change state. In other words don't covert from mechanical energy to electrical and back to mechanical again as done currently. Instead, use hydraulics and CF accumulator tanks. Energy density of energy storage is poor, but efficiency is much higher. You can recover 80 percent of breaking energy as opposed to 30% for electromotive. Goal is to store only enough energy to help with starts up to no more than 30 mph. So hybrid yes.... electric hybrids perhaps not.
> 
> ...


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## Third_degree (Jan 11, 2012)

Please see the following link relative to efficiency of a hydraulic accumulator for energy recovery. In short you are recharging the bladder...

http://lightninghybrids.com/hydraulic-hybrids/hydraulics-vs-electric

So 80% of available energy (Does not count energy lost to drag and so forth as you point out that are also not available to any hybrid system).

As John points out, its the speed of charge that kills the battery concept, unless you severely over-size the battery.


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## Duncan (Dec 8, 2008)

_John said

When a car brakes to a stop from say 100 km/h it can do this in as little as 2 seconds yet our batteries will likely have a power density of C3 meaning the quickest they can be charged or discharged is about 20 minutes or about 1/600th the rate we need if it was optimally sized for the regenerative function of a 100 km/h stop. So we have to fit a battery 600 times bigger than we need to perform this function in order to get sufficient power handling capacity. If we could find a battery with a C60 power density we could hybridize our vehicle with a battery 1/20th the size to add a simple regenerative function.

_*NO*
a 1000kg vehicle at 100km/hour has 375Kjoules of kinetic energy (or 100 watthours) a "normal" stop (not an emergency) would take over 10 seconds - an energy input of 37.5Kwatts
This should be easily absorbed by the batteries

Even if you wanted to brake down from 100Km/hr in 2 seconds you would only be absorbing 187Kw

You still need the mechanical brakes for an emergency _- 

_Your battery pack would be about 30Kwhours so 187Kw would be about 6C - my Headways are 10C continuous or 20C for 10 seconds_

_The mistake is that the battery pack is not sized for a single acceleration to 100Km/hr_

_You would not size your re-gen for an emergency stop -
If you looked at your energy return over a typical period you would not get enough payback at very high braking loads to justify the extra weight

It must be months if not years since I have done an emergency stop from high speed_
_


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## Salty9 (Jul 13, 2009)

High pressure gas also adds a layer of complexity you may not want to deal with. I was working at a shipyard overhauling a sub and they used hp air to spin up the steam turbine after overhaul and they were able to put a section of the turbine thru the pressure hull.


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## Third_degree (Jan 11, 2012)

Hey Salty,

I used to design gas turbine engines for IRES. My favorite part was testing the turbine to failure at 125K RPM. When it breaks (Tri-hub burst), it splits into three 13# projectiles going faster than a bullet. And yes, it makes 2" thick steel barriers look like tin foil. I had to design the containment shield for the test. I was glad I had the SR analyst check my math.... forces are insane!


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## Darxus (May 10, 2010)

Third_degree said:


> P.S....Do you live in NH?


Yes.



Third_degree said:


> Oh.... incomplete response:
> 
> Kamm Tail:
> 
> The answer is the Aptera. They switch from bullet shape to a flat departure / Kamm type tail.


Well, they are still going to get vortices rolling in from just the top and bottom. And I'm pretty sure it would work fine if you had a perfectly cylindrical tail lopped right off - donut shaped vortex. My concern is what happens when you lop off the end of a less regular shaped tail, like mine would work out to. I have a feeling it would work fine, as long as you stick to tapering down to at least 50% of the maximum cross section (which a lot of people seem to neglect), but I haven't seen much about doing that.



Third_degree said:


> Also the Olds Aerotech car from the 90's I think.... has a very good trailing shape. (See the long tail at the bottom)
> 
> http://www.carstyling.ru/ru/car/1987_oldsmobile_aerotech/


Yeah. Have you not seen my web page that goes with this thread? http://www.eternalmachinery.com/ecar/



Third_degree said:


> For examples look at the original VW 1 liter car. They just make a sharp cut at the tail.
> 
> http://www.treehugger.com/cars/volk...d-edition-of-1-liter-car-282-mpg-in-2010.html


Yeah, that thing is very much like what I want. I just want much cheaper, more off the shelf parts, no air bags etc., probably wider, and more sexy looking. And that's definitely a Kamm tail in an irregular shape - if I could just see the CFD analysis of it....

I'd particularly like to have its diesel engine. I'd prefer diesel. Lower cost, volume, and presumably weight per distance than gasoline. But I'm more concerned with using commonly available parts, which is pointing me toward gasoline. These pages have nice info on small displacement diesel engines: 
http://www.gizmag.com/go/4272/
http://en.wikipedia.org/wiki/Diesel_motorcycle

I bet a 1.2 liter Volkswagen Lupo diesel engine would be fun.



John said:


> Even though batteries have an energy density that is a tiny fraction of gasoline, electric motors typically weigh much less than internal combustion engines and have an efficiency that is typically four times the ICE.


Yup. Important parts of the equation, but electric still comes in way behind. Which would still work out fine for lots of people, I'm just not liking how it works out for me, needing to drive 69.4 miles round trip 5 days a week. 50.8 of which is at 65mph.


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## Third_degree (Jan 11, 2012)

Sorry, did not see that thread...

Thanks,

I live in Goffstown, NH


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## John (Sep 11, 2007)

Duncan said:


> _John said_
> 
> _When a car brakes to a stop from say 100 km/h it can do this in as little as 2 seconds yet our batteries will likely have a power density of C3 meaning the quickest they can be charged or discharged is about 20 minutes or about 1/600th the rate we need if it was optimally sized for the regenerative function of a 100 km/h stop. So we have to fit a battery 600 times bigger than we need to perform this function in order to get sufficient power handling capacity. If we could find a battery with a C60 power density we could hybridize our vehicle with a battery 1/20th the size to add a simple regenerative function._
> 
> ...


Be careful not to calculate average power requirements for braking effort. The power needing to be absorbed isn’t consistent. It is proportional to speed. Work = Force x Distance, Power = work / time, speed = distance / time so distance = speed x time, deriving for instantaneous power required at any given speed, Power = force x speed. 100 km/h = 27.778 m/s. 27.778 / 2 seconds = 13.889 N/kg or 13889 N for a 1000kg vehicle so power = 13889 x 27.778 = 385809 W or 386 kW. This would taper down to 0 W at stop. For the 10 second stop this falls to 77.16 kW peak. I calculate about 107 Wh for the stop or about 0.1 kWh. Your battery pack at 30 kWh is still 300 times the needed capacity for regenerative braking. Granted we probably shouldn’t try and size our regenerative braking capacity for every braking eventuality.


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## Duncan (Dec 8, 2008)

_Be careful not to calculate average power requirements for braking effort. The power needing to be absorbed isn’t consistent.

_True - the peak requirement is twice the average - still only 380Kw - and the problem there is more likely to be the motor and drive-train rather than the batteries!_

_The net effect is that electrical re-gen is reasonable and all of the hydraulic or other systems are unnecessary _
_


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## DavidDymaxion (Dec 1, 2008)

That's a link for someone selling the system -- hate to be cynical but I distrust statements that say "Toyota currently estimates their brake regeneration system at 30 percent efficiency, _*while hydraulic brake energy regeneration efficiency is over 80 percent, since hydraulics are not limited by battery charge limits during the regeneration cycle."*_ First I doubt the 80% number even as a best case, and secondly even if it was 100% efficient it would be closer to Toyota's 30% number if overall system efficiency were calculated. Buyer beware!

Can you provide an unbiased link for efficiency? Surely some university or government lab has investigated such things.

Don't forget hydraulic systems also have lessened efficiency at high rates. High rates => more heat generated => more lost energy.


Third_degree said:


> Please see the following link relative to efficiency of a hydraulic accumulator for energy recovery. In short you are recharging the bladder...
> 
> http://lightninghybrids.com/hydraulic-hybrids/hydraulics-vs-electric
> 
> ...


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## Third_degree (Jan 11, 2012)

Noted as to bias... however the EPA did there own independent study (That's why UPS trucks are hydraulic hybrids), and Ford has a similar system in trucks. Trucks have been basis so far because non-CF accumulator tanks are cheap, but heavy. Weight is less of a negative for a hydraulic system because of efficiency of system, and torque of hydraulic motors being able to easily overcome weight during acceleration.

EPA also focused on large trucks as that has the largest potential improvement (compared to making a compact more efficient).

As to doubting efficiency, physics is very clear on this. Each energy conversion carries a penalty. Using motor as generator consumes 10% (for a very high end brushless AC motor). Storing that energy in the battery, takes another hit (and can only be done at a given rate, and takes an AC to DC conversion as well), and generates, heat, and finally taking that energy and converting back to the motor (After AC to DC conversion again, another hit.... 

By contrast, hydraulics are all mechanical (no change of state). So losses are in fluid dynamics, and some heating. Physics is pretty solid on this one.

Here is link to VERY comprehensive EPA study, and why it progressed to full hydraulic hybrids.

http://www.epa.gov/otaq/technology/420r04002.pdf


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## Third_degree (Jan 11, 2012)

Another link regarding hydraulics...

http://auto.howstuffworks.com/hydraulic-hybrid3.htm


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## Duncan (Dec 8, 2008)

a_nd can only be done at a given rate,

_You are back on this again - the rate required for effective re-gen is NOT BATTERY LIMITEDThe reason hydraulics are used is that they are used in addition to the diesel
If you have an electric system then you use the same system for bothHydraulic motors are not 100% efficient - pumping losses can be huge! 
The accumulator uses nitrogen, compressing the nitrogen increases its temperature - the heat energy is lost
Then you run the process backwards - with all of the losses 

Its NOT super efficient and more importantly for your project its definitely NOT lightweight


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## Third_degree (Jan 11, 2012)

Duncan,

David requested a link which I provided. The anger is not needed. I am VP of mechanical engineering. I have 14 Patents ranging from robotics to gas turbines. I'm not a hack, and I have built robotic systems based on this that were lightweight and efficient.

Please feel free to review the EPA, and other articles for yourself. What conclusions you derive after reviewing the available information is up to you.

The complete Ohlins system used to create 2wd motorcycles is 14 lbs, including a pair of hydraulic motors and accumulator. The original link given was for CF accumulators which solve the weight problem for the energy storage device.

At a given rate is true. As I indicated you are using the system for low speed only in stop and go traffic, which is the point of any regenerative system. You are only getting a boost to get the vehicle rolling. You don't need it for the highway, which is why hybrids get better mileage in the city than the highway.

Charging a battery generates heat too. But it is not pure wasted heat energy of a normal braking system.


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## Third_degree (Jan 11, 2012)

http://saeeng.saejournals.org/content/2/2/505.abstract

http://www.scribd.com/doc/55027675/Hydraulic-Hybrid-Drive

I have also performed my own testing that is proprietary... 

Lots of smart people working on this. Every system has a sweet spot. Ultracaps exist for the same reasons as hydraulic systems. To overcome weaknesses in energy recovery using existing battery technology i.e transient response time....


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## Duncan (Dec 8, 2008)

Hi Third
Pardon me for being a GOM (grumpy old man) I look forwards to seeing your lightweight hydraulic system


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## DavidDymaxion (Dec 1, 2008)

The EPA is a much better link, thank you, and I have learned some things. Hydraulic regen is:


Cheap (2ish year payback)
Can be lightweight
Available with current technology
For engine off scenarios, like electric/gas hybrids do, the numbers I saw were 34% and 50% improvement in fuel economy for "full hydraulic."

Now let's look at the EPA number for some cars that come both with regular gas engines, and hybrids:

Civic hybrid 44 44
Civic 28 39
Civic HF 29 41

Toyota Camry Hybrid 43 39
Toyota Camry 25 35

If we combine the numbers like the EPA study, that's an average fuel economy improvement of 31%. BTW the Honda engines were 1.5L and 1.8L, the Camry 2.5L and 2.5L.

The EPA simulations project 34% SUV and 50% car better fuel economy for hydraulic regen. Ford did an actual car that got 24% better, but without an engine-off feature. Actual gas/electric hybrid numbers were 31% better for 2 examples that I computed. So it looks like it is possible hydraulic regen is more efficient than electric regen -- but I would caution that's a simulation, not a real world result for the hydraulic case.


Third_degree said:


> Noted as to bias... however the EPA did there own independent study (That's why UPS trucks are hydraulic hybrids), and Ford has a similar system in trucks. Trucks have been basis so far because non-CF accumulator tanks are cheap, but heavy. Weight is less of a negative for a hydraulic system because of efficiency of system, and torque of hydraulic motors being able to easily overcome weight during acceleration.
> 
> EPA also focused on large trucks as that has the largest potential improvement (compared to making a compact more efficient).
> 
> ...


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## PapaWoodie (Apr 15, 2012)

Hi,

Just encountered this thread today and read all through the posts.

Have a couple of comments, in general.

Regarding the coal / long tailpipe theory against electric cars, there
are a couple of points that are ignored. First, the refining process
for gasoline uses an extremely high amount of electricity. Most EV
conversions use less electricity per mile than goes into one gallon
of gasoline production and delivery (at the pump). In other words,
these full featured cars, based off existing vehicle stock, using LiPO4
batteries, can travel farther on the volts consumed prior to the gallon
of gas arriving in the tank, than the vast majority of ICE vehicles can 
achieve through burning the actual gasoline. 

In comparing ICE vs. EV, the EV has a roughly 8:1 efficiency ratio.

Regen braking, despite the tested and published numbers, is a relative
matter. Driving efficiently to minimize braking, and coasting freely
when practical, will greatly reduce the 'claims' of regen's returns. 
The biggest paybacks from regen braking come from the most wasteful
driving -- fast acceleration and rapid deceleration. And, yes, we all 
encounter instances where that occurs, but to what extent is it the
'norm'...? And is it worth the added expense and complication to our
vehicles? How many more batteries could be substituted for the
same cost, or weight, otherwise involved?

LiPO4 batteries are now reasonably priced. They offer in excess of
several thousand cycles of life at rated capacities, if charged and
discharged appropriately. Just don't over charge or over dis-charge.
And start with a bottom balance pack.

The A123's are now being sold (out of China or Korea), and available
for anywhere from $17 to $35 each for the 20Ah (18.5 Ah) pouch
type format. A pack constructed of these can yield a 60Ah 120V pack
that weighs roughly 225 pounds and measured about 5 to 6 inches
tall in a 2 foot by 4 foot flat battery pack. Placed under a car or even
integrated into the sub-frame, the weight is kept low, which is desirable
and advantageous for reason of stability and minimizing intrusions
into the passenger and luggage compartments. 

The pack as described, involves staggering two rows, each 6 pouches
long and 3 pouches high. The rows face their tabs toward the other,
offsetting one row against the other so that the appropriate + and - tabs
can be jointly connected to adjacent pouches. The 18 cells, thus
connected, yield 120V at 20Ah (3p12s). Stacking 3 such modules 
raises the pack to 60Ah nominal capacity.

A123 pouch cells have been demonstrated to reliable perform up to 20C.

The cost of cells for such a pack would be $2160 at $20 per cell. 
At $35 each the coast rises to $3780 for the pack. This is not too high 
a price premium over a similar capacity lead acid pack. And it reduces
weight by about half a ton. Factoring cycle life and range decline over 
lifespan, the lead acids will likely need replacing in 2 to 3 years. The 
lithium pack would likely last for the lifetime of the vehicle, or a good 
10 to 15 years.

Further, the modularity of this pack design allows one to start off with a
smaller range expectation, and expand capacity in the future, if longer
range was then desired or required. One could start with a 40Ah 120V
pack, in a lightweight vehicle, as proposed here, and readily increase it
to an 80Ah 120V pack, by putting additional 'layers' into the flat pack.

An 80V 60Ah pack, for the motor last discussed above would require 72
cells -- $1440 to $2520 [at $20 or $25 each] at about 150 pounds in a
suitable battery box.

At some point a good overall weight estimate is necessary. Only then
can you begin to compare energy requirements to other similar sized
vehicles. If you comparison averaged 100 watt hours per mile, you
would be able to size an appropriate pack for the desired range. Of
importance to note, is the Watt hour used per mile per pound of overall
weight. Ignoring aerodynamics for now, you can begin to calculate pack
size. Factoring in the improvement of aerodynamics, especially where
such data is provided, you could reasonably adjust your pack size down
by a portion of that. On the other hand, keeping a similarly sized pack,
in spite of those drag improvements, will only provide a greater range,
one with a very satisfying margin of comfort, taking into account detours,
side trips, giving test rides, all without worry of depleting your pack.

But perhaps I've said too much....

Great ideas! Look forward to seeing something being built.


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## Third_degree (Jan 11, 2012)

I'm hopping for this to be the solution:

http://science.howstuffworks.com/environmental/green-science/algae-biodiesel.htm

At least production of it consumes CO2, but harvesting must be optimised

Must look at energy consumed for production such as mining of Lithium...
What country has 90% of this element? China, what does China use for power.... Coal... do they even use emissions controls on the mining equipment.... no....

I LOVE electric cars. But they hinge on the Lithium Air battery taking hold... and other advancements.

Can't deny that the battery is not only not energy dense, but dirty as well to produce, then to dispose of


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## John (Sep 11, 2007)

Third_degree said:


> I'm hopping for this to be the solution:
> 
> http://science.howstuffworks.com/environmental/green-science/algae-biodiesel.htm
> 
> ...


I thought most lithium came from the lithium triangle (Chile, Bolivia, Argentina) I suspect you are thinking of Rare Earth Elements most of which currently come from China but only because they cornered the market by undercutting everybody else not because the natural resource is only there.

Algae culture is something to hope for. Algae can be grown in salt water (read seawater) and so may not impact freshwater supplies. Ideal growing areas would be arid areas close to the ocean where land is cheap and unproductive and seawater doesn't have to be piped very far. This way food crops and freshwater supplies would not be displaced. Also these regions should have higher direct sunlight hours than more temperate or tropical areas. Algae do after all grow hydrocarbon strings from carbon dioxide, water, and sunlight. Having a thermal power station nearby as a CO2 source would also be handy.

We haven't even begun to recycle lithium batteries yet but once more of them are used I think this will happen. This will reduce their impact considerably.


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## Third_degree (Jan 11, 2012)

Thank you for correction (Lithium). You are absolutely right, I must have been thinking rare earth.

And yes, the fact that we don't eat algae is a bonus. The whole Ethanol debacle.... man, I hate when government attempts to be scientists... Less than brilliant

I have re-read your post several times. Great information. I am helping a start-up design an electric motorcycle, and your post was helpful.


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## Darxus (May 10, 2010)

They installed four electric car charging stations in the garage at work, maybe a couple months ago. Got me thinking about electrics more.

My biggest question at this point, is, how do you determine how much of the air should go over the car, and how much should go under? If it was in a tiny tunnel that might be easy. I'm still trying to figure out how to create a program to generate an ideal shape.

My other question is, is there any reason a Sears-Haack body isn't ideal at 65mph (105kph)? It's the theoretical ideal for near- and super-sonic. Although I haven't found anything about minimum length/diameter ratios. And I'm concerned about flow separation in crosswinds due to the pointy front.

I've been playing with Sears-Haack bodies. I know this overall shape isn't ideal, but I think it's fun.

I also still have no idea how to deal with windshield laws. 

And I really need to play with some CFD.


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## Third_degree (Jan 11, 2012)

I continue to enjoy your designs. And in fact they are why I joined the group.

The shape as you know is idealized, but also assumes in space. Meaning airframe. That is so the flow-lines and pressures are equal on all sides.

The closer you are to the ground, the more ground effect you have. That in effect pulls the flow lines tighter under the car, and the velocity increases. As you know this higher velocity (lower pressure) is beneficial to prevent lift. In less aerodynamic cars that have messy under-bodies, the flow slows down and lift is generated.

Same issue for side to side. As a result I would suggest spacing your side-pods further apart to limit the velocity (and skin friction) on the side of the body.

As to distance from the ground... from a pure aero-drag stance, you actually want a fair amount (Like a foot) to minimize the ground effect. But you have to balance this with handling concerns such as height of CG, and having some downforce is useful too. Those issue would want to see you lower it. Perhaps a compromise between typical road cars (5") and the more aero shapes found on solar powered cars which are a foot or more... 

As to cross winds, that is a vector. A 60 MPH forward speed and a 20 MPH side wind still has you somewhat aligned...

Any separation would happen more due to the round body than pointy nose however (The departure angle of a round shape greatly exceeding the number needed for laminar flow).

At that point your options would be golf ball dimples (better on cross winds, but worse drag rest of time), or localized trip strips to attempt to keep the flow attached.

I believe these efforts would be not worth it however. Straight line optimization would have more bang for the buck.

On a side note. I hope your passengers know and like each other very very much


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## Darxus (May 10, 2010)

Third_degree said:


> I continue to enjoy your designs. And in fact they are why I joined the group.


Aw, thanks.



Third_degree said:


> Same issue for side to side. As a result I would suggest spacing your side-pods further apart to limit the velocity (and skin friction) on the side of the body.


I have often played with widely spaced wheels, partially for that reason (well, less specifically, to reduce aerodynamic complication). But that creates a mess with suspension running between the side pods and center (I recently learned catamaran / trimaran terms, maybe I should start using them....). Or at least some kind of connecting beams (containing steering linkages and drive half shafts), and then much more complicated suspension within the pods. At the moment, I don't think it's worth the increased frontal area.



Third_degree said:


> As to distance from the ground... from a pure aero-drag stance, you actually want a fair amount (Like a foot) to minimize the ground effect.


Yep, but I'm much less concerned with what the ideal height is, than how to determine how high the leading edge is compared to the (vertically) thickest part of the car.



Third_degree said:


> Any separation would happen more due to the round body than pointy nose however (The departure angle of a round shape greatly exceeding the number needed for laminar flow).


Sure, but if it had a more round nose, perhaps that would help the wind curve around and attach to the body? I realize there's a limit to how much benefit you can get from that, but I believe it's the entire reason the leading edge of most airplane wings are cylindrical and not sharp, to avoid flow separation at higher angles of attack / sudden stalling.

Oh, that's an interesting point that separation is more likely on a round body. Hadn't thought about that. Still don't really want to make a sail out of the thing....



Third_degree said:


> At that point your options would be golf ball dimples (better on cross winds, but worse drag rest of time), or localized trip strips to attempt to keep the flow attached.


I've read golf ball dimples are a very unusual case and unlikely to be applicable to anything else. Although introducing turbulence to maintain attachment can still be valid.



Third_degree said:


> I believe these efforts would be not worth it however. Straight line optimization would have more bang for the buck.


Thanks.



Third_degree said:


> On a side note. I hope your passengers know and like each other very very much


I'm not planning on anyone riding in the back seat but my girlfriend, or using it to carry groceries. Two capabilities I feel are very worth having. The level of coziness and reduced cumbersomeness are largely inspired by my motorcycling experience.


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## Duncan (Dec 8, 2008)

vastly too much "wetted area" 

you would be better with a single streamlined shape with more frontal area but less wetted area 

As well as the wetted area problem the intersections between the shapes will cause major problems - I would expect you to end up with a lot of drag from those areas


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## Third_degree (Jan 11, 2012)

The best analogy for the designs (which I'm sure you are aware of) are the Aptera, and Edison 2 vehicles....

The Edison 2 using the structural connection from main body to side pod that you described, and the side pods than house the suspension and steering...


Aptera opting for the messy connection style as you describe, and movable pods.

As I believe your intent is to house batteries in the pods, the Edison concept carries weight (yes pun intended).

Quick response to wetted area by Duncan.... That is obviously part of the equation, but a lower order driver than Cd and cross sectional area...

Multiple bodies are a way of minimizing cross section, and also allowing streamlining is shorter length. So if he did a perfect streamlined shape, long enough for shallow departure angles, and wide enough to house everything. He would have a low Cd, but a very large, long, larger croses section, and heavier vehicle.

The trick as you point out is keeping the connections between bodies clean as well.


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## Duncan (Dec 8, 2008)

Third_degree said:


> Quick response to wetted area by Duncan.... That is obviously part of the equation, but a lower order driver than Cd and cross sectional area...
> 
> Multiple bodies are a way of minimizing cross section, and also allowing streamlining is shorter length. So if he did a perfect streamlined shape, long enough for shallow departure angles, and wide enough to house everything. He would have a low Cd, but a very large, long, larger croses section, and heavier vehicle.
> 
> The trick as you point out is keeping the connections between bodies clean as well.


The points about length and weight are correct 

BUT if you do have a "streamlined" shape the drag is purely a function of wetted area - the cross sectional area becomes irrelevant 

The Cd and cross section are only useful for shapes where there is form drag


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## mizlplix (May 1, 2011)

NOTE: the term "Plexiglass" is usually miss used. Most automotive or racecar "Plexiglass" is Lexan, a really different animal.

Plexi is soft, cracks and breaks quite easily. It is a WW2 product.

Lexan is some tough stuff. It is a quality, late model acrylic that is twice the tensile strength of Plexiglass and much harder to scratch. It can be bought with a "H" suffix, meaning it is hard coated. The H Lexan can be wiped off over and over without hazing or scratching.

PLEXI has become just a generic term for window plastic sheeting.

Miz


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## Third_degree (Jan 11, 2012)

Total drag is Cd x CSA....

Motorcycles have terrible Cd, but tiny area.... That's why a Hyabusa can do 200 mph with less than 200 HP, but a Shelby 500 with a Cd that is half of the Hyabusa's needs 650 HP to do the same.


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## Duncan (Dec 8, 2008)

Third_degree said:


> Total drag is Cd x CSA....
> 
> Motorcycles have terrible Cd, but tiny area.... That's why a Hyabusa can do 200 mph with less than 200 HP, but a Shelby 500 with a Cd that is half of the Hyabusa's needs 650 HP to do the same.



Err - No

If you have a streamlined shape (IF) then the streamlines rejoin and there is no form drag

Drag then is proportional to wetted area

Streamlined shapes are rare in automotive circles so that equation is a good compromise BUT if you are going for a stream-liner it's wrong


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## Darxus (May 10, 2010)

Spent some time working on the aerodynamics of the intersection. Then when trying to figure out what tires the Edison 2 used, found Continental's new tires desigend for electrics, and switched to their 125/80R13M. Then I decided to try simplifying things, a lot.









I have always found just the tires + people + motor models... sexy. And the question is what to wrap around them. This model is so very much simpler. One of the things it vastly simplifies is the windshield problem - I think laws require safety glass, and safety glass is basically only available almost flat, cut out of existing windshields. 

Stupid laws.

I'd still like a good way to determine the optimal height of the trailing edge.

And all the flat surfaces I could do with sheet metal... I'm guessing lo-cost builders use sheet metal instead of fiberglass when they can for some good reason, I'd like to know what that is. And I'd really like to be able to pull the entire skin off to show off the internal sexyness, but with this skin it seems like it would almost be a shame not to stress it at all, maybe welding to the frame?




Duncan said:


> you would be better with a single streamlined shape with more frontal area but less wetted area


That doesn't make sense to me. I was going to go into this a lot more, but Third_degree seems to agree with me.



Duncan said:


> As well as the wetted area problem the intersections between the shapes will cause major problems - I would expect you to end up with a lot of drag from those areas


Definitely agree there, that's exactly what I was referring to when I said I know that shape wasn't optimal.




Third_degree said:


> The Edison 2 using the structural connection from main body to side pod that you described, and the side pods than house the suspension and steering...


Oooh. I had looked into the Automotive X Prize cars a fair amount, but never knew the Edison 2 packed its suspension _inside_ the wheels. I feel like I tried to figure out what they were doing for suspension before but couldn't find anything. Found more this time, but... damn that looks complicated = expensive. 



Third_degree said:


> Aptera opting for the messy connection style as you describe, and movable pods.


I just read Aptera went out of business 



Third_degree said:


> As I believe your intent is to house batteries in the pods, the Edison concept carries weight (yes pun intended).


Yeah, but the section containing the batteries would almost need to be supported from the center section completely independently of the connection to the wheels to avoid substantial increase in frontal surface area. Complicated.


I really appreciate the feedback.


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## Third_degree (Jan 11, 2012)

Duncan said:


> Err - No
> 
> If you have a streamlined shape (IF) then the streamlines rejoin and there is no form drag
> 
> ...


 
"no form drag" suggests Cd=0. Even the NSU flying hammock had a Cd of 0.10. It held one of the longest standing land speed records because of it's tiny cross section. It's competition had Cd values that were also 0.1, +/- .01

Without re-writting my thesis... The more air you push out of the way (Cross section), the more work must be done, the more heat is generated, and the higher the skin friction. And since the ideal streamlined shape must get longer to converge the flow lines at the exit of a larger cross section, your wetted area went up anyway.

The smaller cross section wins when it comes to speed and energy needed. Works when talking bullets for sniper rifles, land speed records, Britten motorcycles (fully faired britten had lower Cd but slower, because cross section increased), or electric cars. Zero form drag is tough to come by in the real world.


On Windscreen notes:

Safety glass has plastic as central layer. I believe (But admit I don't truly know) That Lexan is allowed on a car, it's just the difficulty with windshiled wipers. Even the hardest coated Lexan will eventually scratch (Note the Monotracer uses a hard coated Lexan and has windshield wiper, but owners are suggested to use rain X and limit use of wipers).

My designs had three wheels in order to take advantage of motorcycle laws WRT to windscreens (However a full canopy turns it into a car in some states). But three wheels have other draw backs, why I am looking to tilt... yet another layer of complexity.


I understand your KISS theory of latest design...But it's not as cool looking I have to say.... Begins to look a bit Tango-ish almost. May be a way of combining the catamaran with the central body in a best of both worlds kind of way


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## Darxus (May 10, 2010)

Third_degree said:


> Safety glass has plastic as central layer. I believe (But admit I don't truly know) That Lexan is allowed on a car, it's just the difficulty with windshiled wipers. Even the hardest coated Lexan will eventually scratch (Note the Monotracer uses a hard coated Lexan and has windshield wiper, but owners are suggested to use rain X and limit use of wipers).


Huh, nice info, thanks. I think I tried to find out what the Monotracer used and wasn't able to figure that out either. What else do you know about the Automotive X Prize stuff that I should know?  



Third_degree said:


> I understand your KISS theory of latest design...But it's not as cool looking I have to say.... Begins to look a bit Tango-ish almost. May be a way of combining the catamaran with the central body in a best of both worlds kind of way


Heh, you think this looks like a Tango? I suppose, on some level, but the length / width / height ratios are a bit different 

Yes, it looks less fancy, but the simplicity is growing on me. So many things so much easier. And other than looking less fancy, is there any real disadvantage? I still think it looks nice. Perhaps somewhat classy even. I may still play with combinations of the two more.

Switched to a Kamm tail, since I have no doubts that it would work fine here. (Cranked up the Ambient Occlusion quality.)


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## Third_degree (Jan 11, 2012)

Hey Drax,

I had to play too.... So i did a cat / sears body.... Idea is trailing arm rear suspension, rear drive, batteries in side pods.

Front suspension is a bit odd.... leading link earles forks with large trail such that steering head very low. Steering rack to ackermine steering links to top of forks...

As to Tango reference for KISS design.... yes, unfair of me.... only width applies


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## Darxus (May 10, 2010)

Third_degree said:


> I had to play too.... So i did a cat / sears body.... Idea is trailing arm rear suspension, rear drive, batteries in side pods.
> 
> Front suspension is a bit odd.... leading link earles forks with large trail such that steering head very low. Steering rack to ackermine steering links to top of forks...


Wow, very nice. I was trying to clean up the intersection by extending the center out to the sides, your method definitely looks better. And it does look like you have enough width in those side pods to fit the necessary support structure in there. Front suspension you describe sounds very similar to what I last played with on a motorcycle design, and which I was, again, contemplating fitting into pontoons due to your suggestions.

I'm curious what you're thinking about final drive for that. You could just poke some half shafts through. You could do half shafts coming in the top of the pontoons, within the existing fairing, and chains down to the wheels. Heh. I need to try modelling a quad tilter using hub motors, but the EnerTracs seem ridiculously expensive.

What software did you do that with? I have no idea how I'd merge a Sears Haack body into a flat surface like that and radius the intersection with Blender.

I feel like there should be a forum just for wild and crazy ideas like this


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## Third_degree (Jan 11, 2012)

Hey Darx (Sorry for mis-spelled last time)

I used solidworks because renders a bit better (Though I didnt use the rendering tool), I can use ProE also....

Yes I was picturing basically a pair of electric motorcycles in side pods, with hammock in middle...

So motor at the suspension pivot location ahead of rear wheels with rear swing-arm suspension also like motorcycle... chain drive to rear wheels. Again motorcycle front suspension... Use software to match speed of rear wheels with encoders in front wheels to form electronic differential.

Allows super efficiaent shape.... will even have a lower pressure under car than top as velocity will be higher as it forms a venturi tunnel (But high enough as to not generate lots of drag, but some)

But as all wheels move straight up and down handling is only acceptable as can not control roll centers.


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## Darxus (May 10, 2010)

Third_degree said:


> Hey Darx (Sorry for mis-spelled last time)


No problem, that spelling is actually incredibly common.



Third_degree said:


> I used solidworks because renders a bit better (Though I didnt use the rendering tool), I can use ProE also....


That was my guess. I really should play (more) with it.



Third_degree said:


> So motor at the suspension pivot location ahead of rear wheels with rear swing-arm suspension also like motorcycle... chain drive to rear wheels. Again motorcycle front suspension... Use software to match speed of rear wheels with encoders in front wheels to form electronic differential.


I heard somewhere if you just hook two electric motors up to one controller, it automatically just works like a diff. Open / limited slip depending on whether you wire it parallel / series maybe?



Third_degree said:


> Allows super efficiaent shape.... will even have a lower pressure under car than top as velocity will be higher as it forms a venturi tunnel (But high enough as to not generate lots of drag, but some)


I'd rather bring the leading / trailing edges down / in to balance out pressure and reduce drag.

Roll centers are another thing I don't understand well enough.


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## Third_degree (Jan 11, 2012)

Hmmm

Was thinking would want to actively control as to provide steering thrust as with Accura's...

But could have a passive diff as you say with motor controller by setting to constand load, as scrubbing would lead to higher draw, and may compensate...

Good thought.

Roll centers are easy to control of upper lower wish-bone designs, and software is easily available to tweak.... But again, this design does not allow unless you want to muddy up the aero... The three wheeler I uploaded earlier had controlled roll center.

If the CG is kept very low with batteries in side pods, straight up and down may be reasonable approximation.... Possibly tilt the sides outboard a few degrees to force some negative camber to compensate.

As to equal pressure.... You have the ground below, and nothing above, so hard to equalize.... but the jacked up center body makes it pretty close with slight difference to help with stability in cross winds / highway speeds.


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## John (Sep 11, 2007)

Darxus said:


> I'd rather bring the leading / trailing edges down / in to balance out pressure and reduce drag.
> 
> Roll centers are another thing I don't understand well enough.


I've wondered about the tunnel car and whether it would be more efficient to have most of the volume displaced in the tunnel or the outside form of the car. You might be able to do a more efficient pressure recovery in the tunnel where the air flow is confined. You could also reduce the volume displaced by pinching the side pods (thinning their section width) where the pilot pod is fattest. I.e. reducing the displacement of the side pods where the displacement of the pilot pod is at its greatest so as to reduce the peak velocity increase of the airflow in the tunnel. I know this would reduce the volume in the side pods for batteries but some could be put ahead of the front wheels and some behind the rear wheels.

With the wheels moving straight up and down you will have a ground level roll center. With the center of gravity of the vehicle some distance above the ground any lateral acceleration will produce a roll couple to the roll center. The roll center is the geometric point relative to the vehicle body that doesn't move laterally as the vehicle body rolls (tilts) relative to the ground. It is the point where the force due to lateral accelerations is resisted by the suspension (the hinge point if you like). The further the center of gravity is from the roll axis of the vehicle the greater the center of gravity is moved laterally as the vehicle body rolls and the bigger the lever is to produce that body roll. The force due to lateral acceleration multiplied by the distance between the CG and the roll axis will give a torque trying to produce body roll and the spring rate at the wheels will generate the resisting force once the wheels are displace up and down on the outside and inside wheels to create the force differential multiplied by the vehicle track to get the equal and opposite resisting roll torque.


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## Third_degree (Jan 11, 2012)

Thanks John,

If we force a negative camber (Top of the front and rear wheels tip in relative to contact patch). Can we project that center line to create a virtual roll center? This is the trick with the angles, of a upper lower wish bone design, but as the wheels are not actually following that arc, that may be a stretch. But obviously the negative camber has it's own bennefit.

Can still incorporate an anti-roll bar with links.


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## Duncan (Dec 8, 2008)

John said:


> With the wheels moving straight up and down you will have a ground level roll center. With the center of gravity of the vehicle some distance above the ground any lateral acceleration will produce a roll couple to the roll center. The roll center is the geometric point relative to the vehicle body that doesn't move laterally as the vehicle body rolls (tilts) relative to the ground. It is the point where the force due to lateral accelerations is resisted by the suspension (the hinge point if you like). The further the center of gravity is from the roll axis of the vehicle the greater the center of gravity is moved laterally as the vehicle body rolls and the bigger the lever is to produce that body roll. The force due to lateral acceleration multiplied by the distance between the CG and the roll axis will give a torque trying to produce body roll and the spring rate at the wheels will generate the resisting force once the wheels are displace up and down on the outside and inside wheels to create the force differential multiplied by the vehicle track to get the equal and opposite resisting roll torque.


Hi John - with all due respect you have described exactly why "Roll centers" are mythical useless beasts

What you actually have is a series of couples

In steady state
The force due to lateral acceleration multiplied by the distance between the CG and the GROUND
Will equal 
The couple caused by the movement of the suspension
(wheel movement x wheel rate x track)

This is what happens - no roll centers involved - no unicorns either!

Just hold a model car and think of the external forces acting on it

If a vehicle rolls lots and is high there is a secondary torque caused by the sideways motion of the C of G - this is negligible in a car - important in a leaning trike

The other things you need to look at are;
The camber change as the suspension moves and the vehicle rolls
The camber change in dive and squat 

Its a pain - you want the camber to change in roll to compensate for the degree of roll 
But you don't want the camber to change as the car dives and squats!

You can't change the amount of side to side weight transfer in cornering 
It is set by the cornering speed your C of G height and your track
(you can juggle it from the front to the rear)

The fore - aft weight transfer in braking and accelerating is also set by the acceleration/deceleration your C of G height and your wheelbase


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## Third_degree (Jan 11, 2012)

Duncan,

As the suspension can only work up and down in this case, would you agree with just adding some negative camber to help account for the inability to keep the contact patch flat with body roll?

It's understood that it is not a perfect solution.


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## Duncan (Dec 8, 2008)

Third_degree said:


> Duncan,
> 
> As the suspension can only work up and down in this case, would you agree with just adding some negative camber to help account for the inability to keep the contact patch flat with body roll?
> 
> It's understood that it is not a perfect solution.


Hi Third
That would help, as would the obvious other pallatives
Keep C of G as low as possible
Go as stiff in roll as you can - causes problems with single wheel bumps 
Get the track as wide as you can

Or go for the leaning trike (or 4 wheeler) - where you lean into the corner like a bike - then up and down suspension is just what you want - but you need oceans of travel


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## Third_degree (Jan 11, 2012)

Agreed Duncan....

Why I am working on a tilting design myself.... But after modeling that, I may develop it a bit more.

Thanks for your input


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## John (Sep 11, 2007)

Duncan said:


> Hi John - with all due respect you have described exactly why "Roll centers" are mythical useless beasts
> 
> What you actually have is a series of couples
> 
> ...


I’m sorry Duncan but I have to disagree with you. I think there are two different situations at work. Weight transfer due to lateral accelerations and the Vehicle bodies response to lateral accelerations. While I agree with you about weight transfer, for body roll in most suspension systems the wheels don’t move vertically so the couple caused by the movement of the suspension is either not multiplied by wheel movement or not by track as the vector becomes at 90 degrees to the movement of the contact patch (not horizontally) which alters distance and height to CG of the roll couple. I realize this is a different method than I laid out in my earlier post but the net result should be the same. There is usually more than one way to look at a problem. In order for lateral forces to produce body roll the body roll has to result in a movement of the CG in the direction of the force applied to it. The CG has to yield to the force to drive the movement. The more the CG moves the bigger the lever driving the body roll. By your reasoning there is no anti dive or squat geometry and no roll reducing geometry only stiffer springs and lower CG’s combat such things

The location of the drive and the brakes can significantly affect dive and squat. If the brakes and drive are located on the trailing and leading arms the torque they generate is applied to the suspension arms. One way this torque effect can be removed from the suspension and applied to the vehicle body instead is by using double leading and trailing arms with the brakes mounted on hubs and in the case of the drive by mounting the motor/gearbox to the body.


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## John (Sep 11, 2007)

Third_degree said:


> Thanks John,
> 
> If we force a negative camber (Top of the front and rear wheels tip in relative to contact patch). Can we project that center line to create a virtual roll center? This is the trick with the angles, of a upper lower wish bone design, but as the wheels are not actually following that arc, that may be a stretch. But obviously the negative camber has it's own bennefit.
> 
> Can still incorporate an anti-roll bar with links.


If with the negative camber you mean to keep the trailing arm pivot parallel to the axle I think that would put the roll center below ground level. I think it is the direction of movement of the contact patch rather than specifically the axle angle that causes this. You could go in opposite directions with the axle and pivot getting some negative camber and lifting the roll center. I think you would want to limit how far you went with that though. You'll start introducing toe change with bump and droop and it could also have a mild jacking effect. Old cars with swing axles were notorious for jacking where the wheel tucks under and pushes the car upwards. With a single leading arm you could get that effect under brakes. The toe change due to body roll would be in a detrimental direction for handling.


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## Third_degree (Jan 11, 2012)

Good Post John,

Why I like the earles fork..... If connect the brake directly to link you get actual rise from the front brake! So I add a tourque arm to mount the caliper instead so I can tune the exact amount of dive I want (a bit of dive is useful for a motorcycle to add some bite to the front end before turn in), but want no dive at all if on a car....


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## Duncan (Dec 8, 2008)

John said:


> I’m sorry Duncan but I have to disagree with you. I think there are two different situations at work. Weight transfer due to lateral accelerations and the Vehicle bodies response to lateral accelerations. While I agree with you about weight transfer, for body roll in most suspension systems the wheels don’t move vertically so the couple caused by the movement of the suspension is either not multiplied by wheel movement or not by track as the vector becomes at 90 degrees to the movement of the contact patch (not horizontally) which alters distance and height to CG of the roll couple. I realize this is a different method than I laid out in my earlier post but the net result should be the same. There is usually more than one way to look at a problem. In order for lateral forces to produce body roll the body roll has to result in a movement of the CG in the direction of the force applied to it. The CG has to yield to the force to drive the movement. The more the CG moves the bigger the lever driving the body roll. By your reasoning there is no anti dive or squat geometry and no roll reducing geometry only stiffer springs and lower CG’s combat such things
> 
> The location of the drive and the brakes can significantly affect dive and squat. If the brakes and drive are located on the trailing and leading arms the torque they generate is applied to the suspension arms. One way this torque effect can be removed from the suspension and applied to the vehicle body instead is by using double leading and trailing arms with the brakes mounted on hubs and in the case of the drive by mounting the motor/gearbox to the body.



Hi John
Squat and dive can be reduced as you say by using the brake/acceleration torque
BUT
This is actually working by stiffening/softening the suspension the actual couples still balance
So - movement x actual suspension stiffness x wheelbase = Height of C of G x Mass x Acceleration

You can't get around it!

The same in roll -
movement x actual corner stiffness x track = Height of C of G x Mass x Lateral Acceleration

This works unless you have lots of roll when the lateral movement of the C of G comes into play

For a modern car with 4 degrees of lean and a C of G ~ 500mm off the ground this moves the C of G by 34mm - compared to a track of about 1.5 meters

_By your reasoning there is no anti dive or squat geometry and no roll reducing geometry only stiffer springs and lower CG’s combat such things_

I would change _stiffer springs_ to stiffer effective wheel rates
because there are things like anti-roll bars - but they work by increasing the corner rate

Anti dive/squat and anti roll work by effectively stiffening the wheel rates - the weight transfer is still the same - simple dynamics

Now if you start talking about the dynamics of corner entry - it starts to get a lot more complex

I realized the classic roll centers spiel was "sniffy" when an otherwise sensible guy started talking about having the roll centers outside the vehicle and having the vehicle pushed to the ground 

There is a rule of logic called - reductio ad absurdum

It means to reduce to the absurd - you follow a line of logic until it falls off the cliff - then you know it was silly

Roll center logic has silly things happening - things that defy Newtonian mechanics

Newton v Roll centers - not an even match!

_The CG has to yield to the force to drive the movement. The more the CG moves the bigger the lever driving the body roll. _

Unless you mean the simple logic that the higher the C of G the more it moves - which is true if a second order effect 
I can't see what this means?


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## Duncan (Dec 8, 2008)

Third_degree said:


> Good Post John,
> 
> Why I like the earles fork..... If connect the brake directly to link you get actual rise from the front brake! So I add a tourque arm to mount the caliper instead so I can tune the exact amount of dive I want (a bit of dive is useful for a motorcycle to add some bite to the front end before turn in), but want no dive at all if on a car....



That will work - but it works by stiffening the front suspension - it does NOT reduce the weight transfer - the back wheel will still lift if you overdo it!

If a stiffer front suspension cause the front wheel to wash-out it may (may) actually reduce your maximum braking


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## John (Sep 11, 2007)

Duncan said:


> Hi John
> Squat and dive can be reduced as you say by using the brake/acceleration torque
> BUT
> This is actually working by stiffening/softening the suspension the actual couples still balance
> ...


Duncan you already know that work done equals force times distance. The center of gravity has to move in the direction of the force acting on it in order to do work on the vehicle springs. The work done on the springs increases and decreases their compression depending on whether they are loading up or unloading. The work done by the movement of the CG will equal the work absorbed by the springs which is again force times distance. If I could build a suspension geometry that resulted in not lateral movement of the center of gravity with body roll (and I can on paper at least) then there is no work done to be absorbed by the springs and consequently no body roll. I do this by placing the roll center of the suspension on the center of gravity. Note that this does not influence weight transfer which occurs as you say but is an entirely separate problem. If the wheels move vertically the vector perpendicular to the movement of the contact patch will be straight across the ground plane and its minimum distance to the CG will be the height of the CG above the ground. If the wheel moves outwards as it moves up then the vector perpendicular to the movement of the contact patch will point upwards from the ground plane towards the center of the car and the minimum distance to the CG will be somewhat less than its height above the ground. This will certainly mean less lateral CG movement with body roll (less work done) and a smaller moment arm generating the roll force (less roll torque). If wheels dont move verticaly it changes the calculation you've used. I could even build a body that swung like a pendulum and consequently rolled into the corner leaning like a motor cycle. In its simplest terms the pivot of the pendulum is the roll center the spring rate is infinite and the frame linking the pivot to the wheels is just a live axle. This works without violating Newtonian mechanics or affecting weight transfer. Why can’t more complex geometry’s also work? Any reaction the vehicle body has to the forces acting on it takes time and will reduce the sharpness of the responce to changes in direction. Sorry for the thread hyjack guys.


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## Third_degree (Jan 11, 2012)

Mythbusters golf ball car:

http://eatsleepgolfca.blogspot.com/2012/03/golf-ball-effect-dimpled-car.html


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## John (Sep 11, 2007)

Third_degree said:


> Mythbusters golf ball car:


That is really interesting. Because a car is not omni-directional like a ball they could have just applied the turbulators to specific areas of the car where they produce a beneficial effect rather than all over and instead of using dimples they could have used something directional and aligned to the airflow. With the tunnel car you effectively have a nozzle feeding into a diffuser. Diffusers are much more difficult to get right than nozzles and diffuser stall is a risk where a volume of spent air (separation bubble) stalls in the diffuser blocking its action using turbulators to mix the almost spent boundary layer with the higher energy air further away from the surface delays flow separation by reenergizing the boundary layer. The pressure recovery in the diffuser is never going to be back to ambient as some energy in the airflow is always going to be lost to friction this means some negative pressure will still exist at tunnel exit and this multiplied by tunnel exit area would give tunnel drag force. Turbulators could be used to help achieve a higher pressure recovery. Another method used on an experimental aircraft was to use grids of tiny holes in the aircraft skin to suck away the boundary layer as it became spent. This never moved beyond experimental as keeping thousands of tiny holes clear was a maintenance nightmare.


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## Third_degree (Jan 11, 2012)

I was shocked. The dimples are huge too..... It's not like 3M riblet film that is used just on transition areas.

There is also a product called Fastskins that says they increase MPG by 20%... does tiny dimples. I have not seen that independently verified though


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## Duncan (Dec 8, 2008)

John said:


> Duncan you already know that work done equals force times distance. The center of gravity has to move in the direction of the force acting on it in order to do work on the vehicle springs. The work done on the springs increases and decreases their compression depending on whether they are loading up or unloading. The work done by the movement of the CG will equal the work absorbed by the springs which is again force times distance. If I could build a suspension geometry that resulted in not lateral movement of the center of gravity with body roll (and I can on paper at least) then there is no work done to be absorbed by the springs and consequently no body roll. I do this by placing the roll center of the suspension on the center of gravity. Note that this does not influence weight transfer which occurs as you say but is an entirely separate problem. If the wheels move vertically the vector perpendicular to the movement of the contact patch will be straight across the ground plane and its minimum distance to the CG will be the height of the CG above the ground. If the wheel moves outwards as it moves up then the vector perpendicular to the movement of the contact patch will point upwards from the ground plane towards the center of the car and the minimum distance to the CG will be somewhat less than its height above the ground. This will certainly mean less lateral CG movement with body roll (less work done) and a smaller moment arm generating the roll force (less roll torque). If wheels dont move verticaly it changes the calculation you've used. I could even build a body that swung like a pendulum and consequently rolled into the corner leaning like a motor cycle. In its simplest terms the pivot of the pendulum is the roll center the spring rate is infinite and the frame linking the pivot to the wheels is just a live axle. This works without violating Newtonian mechanics or affecting weight transfer. Why can’t more complex geometry’s also work? Any reaction the vehicle body has to the forces acting on it takes time and will reduce the sharpness of the responce to changes in direction. Sorry for the thread hyjack guys.



Hi John

Like your energy conservation - could be useful for some calculations

let's go back to first principles - what is suspension for?

As you travel along the ground there are discontinuities - bumps 
If you had an infinitely rigid car and wheel you would see infinitely high forces (and break something) 

So the wheel has to be able to lift upwards when you hit a bump, 
And the vertical wheel rate will be limited dependent on the corner mass and the sportiness of the car

Your suspension *must *have this feature 

Your wheel may move in and out or front and back as well but these are extra movements - and normally severely detrimental!

Your suspension must have a vertical wheel rate - 

when you corner you develop a load shift - Newtonian mechanics

A change in load will move the wheel relative to the vertical wheel rate

Any weird and wonderful geometry that reduces that movement effectively increases the vertical wheel rate

Like Anti-dive operates by increasing the effective front wheel rate

This is an area where I was really pissed at the FIA (F1) when they banned active suspension - that is a way to get around this problem

Increasing the effective corner stiffness will reduce roll - but it will increase harshness and in the extreme reduce grip

Active suspension is the only way around this! - It will be developed for us eventually 

Now if somebody like Third Degree can make a system that has sensible wheel/corner rates but that uses an actuator to move the spring units in cornering then we can get semi active suspension - Citroen used something like this on some of their hydraulic suspensions

The key is in sensing the cornering and moving the spring units


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## Third_degree (Jan 11, 2012)

I don't have to...

Cadillac (GM) deveoped Magnetorheological fluid such that they can actively adjust damping.

New Ferrari does not even use anti-sway bars....

In fact the new Koenigsegg has the following design:

Triplex rear suspension
Christian von Koenigsegg has invented a new type of rear suspension system for a road car – Triplex rear suspension. The Agera R comes with the Triplex rear suspension system as standard and therefore has a shock absorber and spring connecting the right and left rear wheel. This system gives unique benefits as the two rear wheels can influence one another when desired.
There are multiple benefits of this system. For example, the Triplex system works in series with the normal springs and dampers, allowing their spring and damping rates to be lowered. This results in increased comfort and better handling on rough and wet surfaces without compromising dry track handling.
The Triplex system also has an anti-squat effect. Traditional anti-squat systems are designed into the geometry of the suspension. These systems do not add any components or weight. However they compromise the geometry of the suspension for other aspects of handling aside from anti-squat.
By adding the Triplex system, Koenigsegg can maintain true suspension geometries for handling, but still have the anti-squat feature and harvest other new found benefits. As the Triplex system compliments the normal dampers and springs, these can be made lighter. Hence, the added benefit does not significantly affect the overall weight of the car’s suspension.

As a roboticist I'm sure I can come up witha sensor array that could do some active control, useing a vision sensor from Leap Motion...


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## Darxus (May 10, 2010)

John said:


> I could even build a body that swung like a pendulum and consequently rolled into the corner leaning like a motor cycle.


I've wondered about this before. It seems like it would be good, if you could get it to work - for a car to lean the right way in turns. Has anybody done it, even in a small model? If not, why not? Is there a reason this wouldn't actually be useful?



John said:


> Sorry for the thread hyjack guys.


I certainly don't mind, I love this stuff.


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## Third_degree (Jan 11, 2012)

Hello Darxus,

As I mentioned before I got into electric cars from the automotive X Prize, as the rules and calculations favored electric cars. But as I looked into the cost effectiveness of different designs, a lightweight gas powered vehicle (Much like Edison 2), ends up making the most sense.

Also, what becomes instantly obvious is the enclosed motorcycle is simply as effecient as you can get. Lower cross section, lower weight, lower rolling resistance, even the tires have a lower cross section. It's really the best way to make an electric vehicle with the least expensive and lightest battery pack, that also has the lowest charge time....

The problem becomes the dorky training wheels. In fact making something with skids would not have the same poor perception.

So anyway, that line of reasoning steers one to a tilting trike or quad design as the best of all worlds giving the smallest cross section, steller handling (exceeding that of a car, or bike), and even giving a level of safety from low-sides, and high sides. 

Since that time I have researched, studied, and designed along those lines, and come to 3 basic designs (as others have as well)...

Free Leaner, Carver based Control, and FTC. My design is actually a hydraulic assisted free leaner, but as you study the carver design, they have really perfected it (The functional symplicity of the tilt is terrific). May be tough to beat it.... So Anyway... here you go.

As to FTC (Free to caster) Its effective, but actually ilegal currently, and reaction time is behind that of a free leaner or carver...

Enjoy the video of the carver!

http://www.youtube.com/watch?v=zb-MIuXTlEs


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## Darxus (May 10, 2010)

Third_degree said:


> As to FTC (Free to caster) Its effective, but actually ilegal currently, and reaction time is behind that of a free leaner or carver...


Wow, I didn't even know about free-to-caster. That's crazy  I'd rather just counter-steer (free to lean). (And of course wouldn't object to you using it if it makes you happy). 




TomA said:


> Regardless, I really think 750lbs of any batteries is going to render your project unworkable, or at least compromise it irreparably.


"With 2,000 lbs under the floor (mostly batteries), it is ballasted to achieve the rollover threshold of a sports car." - Tango, http://www.commutercars.com/.

I've been re-reading this thread, and thought this was interesting.


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## John (Sep 11, 2007)

Duncan said:


> Your wheel may move in and out or front and back as well but these are extra movements - and normally severely detrimental!
> 
> Your suspension must have a vertical wheel rate -
> 
> ...


Duncan, 
A picture is worth a thousand words.










http://www.diyelectriccar.com/forums/album.php?albumid=182&pictureid=1043

In the lower picture if you resolve all the forces acting on the suspension you would get the reactions at the contact patches the same as the simple weight transfer case. The watts link creates a roll center at the center of the verticle link. The CG will pendulum outwards causing the body to roll into the corner. The lateral forces are transfered to the live axle via the watts link. In vertical bump the springs would still produce their respective wheel rates. Note that the reactions at the contact patches in the weight transfer case are not verticle but contain a lateral component. Equal and oposite forces as required.

Darxus,
Having the body pendulum outwards on corners would be unhelpful as it would serve to exagerate weight transfer problems by shifting the center for weight transfer from the center of gravity up to the pivot point i.e. even further off the ground. It wouldn't be at all like a motor cycle where the pivot point is at ground level.


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