# Project Soylent Green



## Inquisitor (Jun 21, 2008)

I would like to introduce my project and goals. Soylent Green is a minimalistic commuter EV to be built relatively cheaply. I know it would be far easier to take a donor vehicle and convert it, but an important aspect of the project is my enjoyment of the design and building process and just figuring out things. I’m fortunate in that my job is only seven miles away in an area that is relatively flat. Basically, I can ride a bike to work (and have) but the traffic is very bad all the time and I feel like I’m taking my life in my hands every time I try it. So without further explanation…


· A minimal weight and price vehicle
· Reverse Trike configuration
· Carries two people occasionally
· 45 mph top speed
· Enclosed for aerodynamics and keep out the rain
· one hour duration or approximately 20 mile range

I’ve started accumulating some of the hardware necessary and running numbers. I currently have…

· the motor 130 Volts, 10 Amp which claims to put out 2.5 horsepower continuous. I’m hoping for closer to 4hp for short periods. 










· I’m going to use a microprocessor (Arduino) for many things, including motor controller, tachometer, speedometer, BMS, temperature sensors, and charge controller and anything else I can think of along the way. Here it is bread boarded to control and LCD screen and as a tachometer. Its showing the motor at 37 Volts running at 1248 rpm.










· The rear wheel, tire, brake disk, brake caliper, rear sprocket, bearings, spacers and axle










· Front suspension off a Honda ATV which includes brake disks and calipers










I’m not really an artist, being more of an engineer so I’m showing the guts first and will do the “artist impressions” later once I’m on a roll. Here is the first cut at the chassis and suspension system. At the moment, it is not fully triangulated around the passenger compartment and is not intended to be fully representative. I plan to start doing some Finite Element Analysis in the next couple of days to fully analyze the structure. But I want to see how weak this minimal, first cut is.









Cost and Weight summary.
Item, Cost, Weight (lbs), Notes
Motor, $50, 15.8, 130 V, 10 Amp, 2.5 Hp
Full front suspension, $162, 28.5, Includes brakes
Front wheels and tires, TBD, 30.0, Not found yet
Rear wheel, $80, 20.5, Tire, brakes and misc.
Microprocessor, $20, 0.1, and misc. electronic parts
Rear suspension, ?, 4.3, Steel tubing already had
Minimal chassis, ?, 30.4, Steel tubing already have most


*Totals *$312, 129.6 lbs, More to come.


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## Inquisitor (Jun 21, 2008)

I hope it’s not a problem that I posted this on both the diyelectriccar.com and the endless-sphere.com. One forum seems to do things on a far larger scale and the other does smaller and lighter. I’m hoping that I can get constructive feedback from both camps. I think both have a lot to offer.
Thanks.


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## Ziggythewiz (May 16, 2010)

Inquisitor said:


> I hope it’s not a problem that I posted this on both the diyelectriccar.com and the endless-sphere.com.


By posting there you have incurred our wrath and shall be shunned!

Looks like you're off to a good start. There are a few here who have/are doing custom builds, but as you said, most of us take the easy way out by converting. 

Welcome, you're in for a fun ride!


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## Woodsmith (Jun 5, 2008)

Seems a good project, it will be interesting to see how it develops.



Inquisitor said:


> I hope it’s not a problem that I posted this on both the diyelectriccar.com and the endless-sphere.com. One forum seems to do things on a far larger scale and the other does smaller and lighter. I’m hoping that I can get constructive feedback from both camps. I think both have a lot to offer.
> Thanks.


Put a link to your endless-sphere thread. Sometimes it can be useful to see what other advice there is.


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## MalcolmB (Jun 10, 2008)

Looks like you've made a good start. Good idea posting on both forums – I'm sure you'll get very different advice.

I've thought about doing something like this for ages, but after building a recumbent pedal trike I was put off by the thought of driving alongside SUVs in traffic. There's a bit of a conflict between keeping the CG low and asserting some road presence. It'll still be a big step up from riding a bike though. A whip antenna with a high-viz flag might be a good idea.

I like the start you've made on the frame, and the running gear choice looks just right. That motor is relatively high voltage/high speed, have you estimated what reduction ratio you're likely to need? And, getting ahead a bit, have you decided on the materials for the skin?

Good luck!


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## Salty9 (Jul 13, 2009)

Subscribed. Have you checked? http://www.locostusa.com/forums/viewforum.php?f=39&sid=1d8c1d4fda4af2ad7041dc3cd479b92e


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## Inquisitor (Jun 21, 2008)

Woodsmith said:


> Seems a good project, it will be interesting to see how it develops.
> 
> 
> Put a link to your endless-sphere thread. Sometimes it can be useful to see what other advice there is.


 
Over there, I put it in the "Large EV General Discussion" while here most will consider it a toy.  
http://endless-sphere.com/forums/viewtopic.php?f=34&t=43496&sid=1bcb6510a57103ea27133a5ed2dd8dd9


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## Inquisitor (Jun 21, 2008)

MalcolmB said:


> ... I was put off by the thought of driving alongside SUVs in traffic. There's a bit of a conflict between keeping the CG low and asserting some road presence...
> 
> I like the start you've made on the frame, and the running gear choice looks just right. That motor is relatively high voltage/high speed, have you estimated what reduction ratio you're likely to need? And, getting ahead a bit, have you decided on the materials for the skin?


*SUV’s – *Exactly! They’re a dime a dozen around here. I plan to be in the 45” inch range for height and it’s currently around 66” wide so it will be “in the way.” I plan to use a LOT of LED lights and probably will have a stalk sticking up with more brake lights on it to be IN THEIR FACE. 

*Motor/Gearing *– I have figured out the gearing based on the rated hp/rpm ratings to get my 45 mph, but my calculations are predicting dismal acceleration with that. I’ve been trying to figure out some way to do a two speed transmission… bike type derailers probably. 

*Skin *– Fiberglass. My biggest unknown is the windshield… I’ve started looking around the home built airplane forums for blown canopies how-to’s.


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## Inquisitor (Jun 21, 2008)

Salty9 said:


> Subscribed. Have you checked? http://www.locostusa.com/forums/viewforum.php?f=39&sid=1d8c1d4fda4af2ad7041dc3cd479b92e


No, but have now . Thanks... I skimmed through the first sticky. "_Chassis rigidity and FEA_". 

I am a lot more secure in doing FEA than most of them appear to be and trust it more. Far more than my ability to weld. And certainly since I can't just trial and error it a hundred times, I really don't have a better choice.


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## Salty9 (Jul 13, 2009)

I forgot to mention checking your state's vehicle requirements. Here in Oregon 3 wheelers are classified as motorcycles and requirements are less stringent than for cars.


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## Inquisitor (Jun 21, 2008)

Salty9 said:


> I forgot to mention checking your state's vehicle requirements. Here in Oregon 3 wheelers are classified as motorcycles and requirements are less stringent than for cars.


As a matter of fact, having read these kind of comments here on this forum was the main driving force for the 3 wheeler. I figured I wouldn’t have to meet crash barrier requirements and such. I will probably be in conformance with lighting. I want to be seen. No matter what I do for impact, running up against an Escalade is not a survivable situation. Even a Smart car doesn’t have much chance in that confrontation.

I haven’t checked here in Georgia yet, but I'm wondering if I will be able to squeeze under the moped rules and forgo any kind of licensing.


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## MalcolmB (Jun 10, 2008)

Inquisitor said:


> I’ve been trying to figure out some way to do a two speed transmission… bike type derailers probably.


Here's a novel (old) idea that might work for a lightweight trike: http://www.endless-sphere.com/forums/viewtopic.php?f=28&t=7679&start=0

You reverse the motor to get second gear.


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## Inquisitor (Jun 21, 2008)

MalcolmB said:


> Here's a novel (old) idea that might work for a lightweight trike: http://www.endless-sphere.com/forums/viewtopic.php?f=28&t=7679&start=0
> 
> You reverse the motor to get second gear.


Real cool idea! Unfortunately, it would eliminate the ability to put the car in reverse and/or use regenerative braking.


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## Inquisitor (Jun 21, 2008)

*Suspension Geometry using Finite Element Analysis*

I wanted to give an update on Soylent Green. I’ve gone through a little research looking for a free/open source Finite Element Analysis program. I settled on Z88Aurora (http://www.z88.de/). Although, it is sponsored by what appears to be college professors and their graduate students at a Germany university, they have been very helpful and are able to communicate with me in English. Also, all the documentation is available in English. Overall, it’s been a great experience. Per one of their primary goals, it is very easy to come up to speed using their software. They even have on-line video tutorials.

It has been twenty years since I’ve used FEA. I have been able to read through their documentation, build test cases and then build a first model of Soylent Green. I attribute this directly to their software. If you have ever used FEA software it is often a monumental effort just to get to first base… and that is after you have spent large sums of money and read through thousands of pages of documentation and/or a willingness to delve into Linux.

This first Soylent Green model is not for evaluating strength. It is to simulate the suspension geometry and motion it will go through in different load situations. For instance this video is under normal gravity, at maximum braking and maximum cornering. I need to make sure of the geometry for things like comfort, without bottoming out, tire position for cornering, and other things. Since springs “deform” a great deal as compared to steel tubing, only non-linear FEA programs can handle this situation. Z88Aurora, makes that very easy to accomplish.

Anyway, here is the video of the first model in action: http://screencast.com/t/ZsykEVolGrar


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## Salty9 (Jul 13, 2009)

Your comments about a trike surviving a collision with an Escalalde prompted me to consider ways to protect the trike occupant(s) in such a collision.

I had been planning a tadpole trike with the occupant(s) suspended from a roll cage in a web made of strapping forming a seat which includes a 5-point harness. I planned on the roll cage being rolled from high-modulus tubing. (I don't trust my welding either).

Your remarks about FEA led me to wonder if such analysis could be done on the occupant(s), roll cage, and restraints to determine shock absorber-snubber requirements?


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## Inquisitor (Jun 21, 2008)

Salty9 said:


> Your comments about a trike surviving a collision with an Escalalde prompted me to consider ways to protect the trike occupant(s) in such a collision.
> 
> I had been planning a tadpole trike with the occupant(s) suspended from a roll cage in a web made of strapping forming a seat which includes a 5-point harness. I planned on the roll cage being rolled from high-modulus tubing. (I don't trust my welding either).
> 
> Your remarks about FEA led me to wonder if such analysis could be done on the occupant(s), roll cage, and restraints to determine shock absorber-snubber requirements?


You remember those frames that hold multiple steel balls where you pivot one up on the end and let drop and the one on the other end flies up. If you drop two, two on the other end will fly up? With an Escalade tipping 6000 lbs and a Smart car around 1500… it’s like dropping four balls when there is only one left. Do you remember what happens with the one?

Ignoring car parts piercing the body, the next thing that kills people in a car wreck is sudden deceleration. Under a certain deceleration, people live… over… they don’t. As the difference in mass (weight) between the two colliding bodies differ, the lighter one feels higher deceleration, the heavier one lower deceleration. Imagine a bug hitting the windshield of the Escalade. The Escalade occupants won’t even notice the very miniscule deceleration (that does occur) by the impact. The bug’s experience is a little more, shall we say… abrupt. 

Ignoring car body crushing (for a moment), its primarily about the difference in the weight of the two vehicles. A person on a bicycle, like the bug, has no chance. A person in a 600 pound EV (like I’m planning)… no chance. A person in a Smart Car… no chance. As you get closer to the Escalade’s 6000 pounds, your odds get better and better. A typical four door sedan at around 4000 pounds will still feel a higher deceleration than the Escalade occupants, but they’re a lot more likely to live than the bug.

_As a side note, at this point… You know all those government crash worthiness ratings… there is some fine print. The crash survivability rating is based ONLY against vehicles of the same type. They are meaningless when comparing two different vehicles and especially two of hugely different weights. In other words, you want your 16 year old daughter in an Escalade… and everyone else in the world doesn’t want your 16 year old daughter in an Escalade!_

Now, let’s look at crush zones. The thing about deceleration… it’s calculated based on the distance you go from say 40mph to zero. If you do it in six inches, you have no chance, if you do it in 100 feet, it’s like normal braking at a stop light. Because of the crash survivability ratings, car manufacturers have spent more testing and FEA time trying to improve that distance part. If your car is VERY rigid, you decelerate very quickly and you die. If it crushes and deforms, it absorbs energy and doesn’t transmit the deceleration to you, so you live. Air bags decelerate your body over a longer distance. A five point harness will actually increase you deceleration as compared to a lap belt / airbag combination and thus increase your likeliness to harm. 

So for a very long winded answer to your question… FEA, in general, can help design a car against vehicles of similar weight. It can show you that your chassis is two soft and will crush you or two rigid and decelerate you too quickly. Generally, you would want the part directly around you to be very rigid so things don’t crush into you. But you want the rest of chassis in front of your feet and behind your back to be less rigid so that it does crush and thus absorb energy that you don’t have to take. Unfortunately, chances are, you won’t be running into other vehicles of the same weight as yours. Although there are FEA programs that can do that kind of crushing (and some are free) the one I picked can’t.

So… really the only answer is… don’t get into a crash. I know that sounds like a stupidly obvious statement. But it’s the strategy of most light vehicles. Sports cars must be light to perform; they’re also nimble so they talk about avoiding the accident that the Escalade can’t serve to miss. Motorcycles don’t mess with any kind of crash worthiness because of this weight difference. They also consider that the odds of living go up because you are catapulted away from the offending vehicle. If your destiny is to hit a tree, well you still lose. If, on the other hand, you are fortunate to land on flat ground and decelerate over a long distance, you get a bad case of road rash, but otherwise, you live.


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## Inquisitor (Jun 21, 2008)

*So what is the FEA for?*

Well, first and foremost, this is a hobby project. I’m not making this car to be my only car that I have to depend on for me and my family’s transportation needs. I used to do a lot of FEA analysis a long time ago and I wanted to mess around with it again. I don’t have any fear of it and I know its limitations and its strengths. It is very accurate when used properly. It also can be very inaccurate and misleading if not used properly. Pretty stress and deflection plots don’t mean its right!

What I’m using FEA for is to check suspension geometry, and to make the chassis strong enough to handle all normal, working conditions… not crash conditions. For these relatively simple tubular frame chassis, it can show you where you’re using too little or too much material. So it can tell you where to increase the number of tubes or the size of a tube… or in the other direction, show you where you can remove or reduce the size of a tube. It allows you to build a stiffer, stronger and lighter structure. 

Since every pound of increase in the frame requires a bigger motor. And a bigger motor requires more batteries. And batteries are by far the most costly item on the car. I may save hundreds or maybe even thousands of dollars on batteries. Besides there is something I want to try that absolutely requires a minimum weight vehicle.


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