# Emrax/Enstroj: 11kg 150Nm 30kw 1900rpm ???



## Jordysport (Mar 22, 2009)

Looks interesting dependent on price.


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## maxvtol (Nov 11, 2009)

gor said:


> any experience with this motor? numbers seems overrated - 5 times to it's counterparts ...


No experience with this motor, but power density looks to be similar to the more powerful RC motors I've seen. Will need lots of air to cool, and I'm sure it's sensorless, not sure how well it will work for EV.


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## Posthumane (Feb 21, 2010)

I recently inquired about these motors for another aircraft application. They are currently not for sale to individual customers, but will be soon. Right now they are only taking orders in batches of 50 or more. The price I was quoted was around 1900 euro. This is for the 200 VDC rated motors. They are indeed sensorless, and they sell the appropriate sensorless controllers as well for about 2500 euro.

As stated, they have a high power to weight ratio, which means that heat dissipation is critical. They specify 20m/s continuous airflow at 25 degrees Celsius. While that is certainly achievable in an aircraft, air cooling this motor in a a car or motorbike would be difficult. That being said, their specs also offer water cooling as an option, though I don't know if they are producing any motors with this option yet.

Perhaps it would be possible to try a group buy for people who are interested in these?


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## Jordysport (Mar 22, 2009)

Posthumane said:


> I recently inquired about these motors for another aircraft application. They are currently not for sale to individual customers, but will be soon. Right now they are only taking orders in batches of 50 or more. The price I was quoted was around 1900 euro. This is for the 200 VDC rated motors. They are indeed sensorless, and they sell the appropriate sensorless controllers as well for about 2500 euro.
> 
> As stated, they have a high power to weight ratio, which means that heat dissipation is critical. They specify 20m/s continuous airflow at 25 degrees Celsius. While that is certainly achievable in an aircraft, air cooling this motor in a a car or motorbike would be difficult. That being said, their specs also offer water cooling as an option, though I don't know if they are producing any motors with this option yet.
> 
> Perhaps it would be possible to try a group buy for people who are interested in these?


Jesus that is expensive, i will stick to my Kostov and Zilla thank you.


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## gor (Nov 25, 2009)

Posthumane said:


> I recently inquired about these motors for another aircraft application. They are currently not for sale to individual customers, but will be soon. Right now they are only taking orders in batches of 50 or more. The price I was quoted was around 1900 euro. This is for the 200 VDC rated motors. They are indeed sensorless, and they sell the appropriate sensorless controllers as well for about 2500 euro.
> 
> *As stated, they have a high power to weight ratio, which means that heat dissipation is critical. They specify 20m/s continuous airflow at 25 degrees Celsius. While that is certainly achievable in an aircraft, air cooling this motor in a a car or motorbike would be difficult.* That being said, their specs also offer water cooling as an option, though I don't know if they are producing any motors with this option yet.
> 
> Perhaps it would be possible to try a group buy for people who are interested in these?


20m/s= 72km/h=45mph
1kw blower normally provides 200-300 CFM at 185-215 mph airflow


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## samborambo (Aug 27, 2008)

Jordysport said:


> Jesus that is expensive, i will stick to my Kostov and Zilla thank you.


11+ motor units @ 1500 euros each. Their BLDC controllers are 2000 euros each for 11+ units. That's around US$4800 for a 50kW peak system. 

I think their controller is a bit expensive. A Kelly controller like http://www.newkellycontroller.com/product_info.php?cPath=70&products_id=727 is US$2000 but would be suitable for the Enstroj motors ordered wound for half the voltage / twice the current.

They do have an option for hall sensors. Shaft encoding is also an option with some other controllers.

Perfect motor for a sports motorbike with A123 20Ah pouch cells.

Email Roman at Enstroj for more information. He was very responsive to my email. I agree that a group buy would be a great option. Maybe EV Components want to carry some stock?

Sam.


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## frodus (Apr 12, 2008)

samborambo said:


> Maybe EV Components want to carry some stock?
> 
> Sam.


What is the intended market? Motorcycles?

Most motorcycle guys wouldn't be able to afford $5k for motor/controller, and its not very likely that someone would use one in a car.

I can ask, but It'l likely be a No unless we can prove a need/organize 11+ people to buy them before we purchase.


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## samborambo (Aug 27, 2008)

frodus said:


> What is the intended market? Motorcycles?
> 
> Most motorcycle guys wouldn't be able to afford $5k for motor/controller, and its not very likely that someone would use one in a car.
> 
> I can ask, but It'l likely be a No unless we can prove a need/organize 11+ people to buy them before we purchase.


I suppose you get what you pay for in power to weight and efficiency. What's the next best option, the Etek BLDC?

Sam.


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## frodus (Apr 12, 2008)

Nah, maybe the Agni motor.

I mean its a good power to weight, just not powe/weight to cost ratio.


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## Posthumane (Feb 21, 2010)

Samborambo, when did you get your prices from him? I'm going off an email from about 2 weeks ago. It's good news if they've gone down since then. I agree that the price is a bit steep for a motorcycle application.

For an aircraft application where weight is critical they are a good option, and at a lower price than motors from OEM suppliers with similar power/weight ratios (such as UQM). We are considering using two or three of these in series for the electric long-ez project at PanLogie Aviation. Roman does seem to be quite responsive as you say. I don't know if I'd be able to lead a group buy of these at the moment if there aren't many other interested parties, as $30k is a bit much to risk at the moment.


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## crowley.daniel (Sep 16, 2011)

Has anyone bought and used one of these Emrax motors? I've seen lots of people recommending them as possibilities, but haven't seen anyone giving a review?

Cheers,


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## lkcl (Sep 16, 2011)

gor said:


> any experience with this motor? numbers seems overrated - 5 times to its counterparts ...


it's an "outrunner" - in other words, the electromagnet is stationery and the magnets are what spin, on the *outside* - i.e. on the inside of the rotor.

if you've heard of the "LRK TorqueMax" design, this is what this motor appears to be.

the consequence of this design is that it is insanely efficient, and produces pretty much constant torque at virtually all RPM ranges.

PML Flightlink were the first people to do a wheel-hub motor based around the LRK Torque-Max design, and they initially did *not* believe the efficiency ratings, and produced datasheets of 6kW, 11kW and 15kW for their three prototype wheel motors. when they actually tested them, they had to hurriedly redo them as 7kW, 13kW and 18kW! 

the other thing about the LRK TorqueMax design is that they _should_ be achieving 97 to 98% efficiency. if they've only got 95% then there's actually quite a bit of room for improvement still to go.

but - yeah, these guys _deserve_ to succeed. 11kg when everyone else is doing 100kg, and the pricing really is about the same, because it's the copper and the magnets that are the major cost factor. if you look at the price for example of the Warp 11 (which is about 30kW) it's $3,000. so this really is about the same kind of price.

now, i looked up the price of the kelly 144v controller: it's $USD 600 (not $EUR 2500 for the recommended 200v one) and you get a reduction in rated torque to _only_ 86Nm (144Nm peak for 2min), and _only_ 21kW, for a big hefty cost saving. yes you could probably find a cheaper 21kW motor but i don't think you'll ever find a competitor product that's 11kg in weight, 95% efficient and has a peak torque that high.

so yeah damnit support these guys so they don't go the way of PML Flightlink!

l.


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## lkcl (Sep 16, 2011)

frodus said:


> What is the intended market? Motorcycles?
> 
> Most motorcycle guys wouldn't be able to afford $5k for motor/controller, and its not very likely that someone would use one in a car.


because i can guess, with a high degree of confidence, that it's an LRK TorqueMax design (and i can see it's an "out-runner" from the engineering diagrams on the web site), i have confidence in this motor because although it is unusual i understand it.

so yes i am planning to use this in a car - not as wheel hub motors but as connected to a standard 4-speed or 5-speed transmission.

reason: i have to hit an 80% or greater efficiency for the drivetrain for the application i have in mind. if i can get 85 or even 90% efficiency (yes, direct-drive wheel hub motors would be great but it's too expensive and also cannot get up gradients) that's just bonus. i'll be happy with overall 80%, and this motor, with 95% efficiency at the higher end of the RPM range is just what's needed.

i'd say this is complete overkill for a motorcycle  you'd have to be a complete nutter to use it - like... ooo i dunno... drag-strip racing or something.


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## lkcl (Sep 16, 2011)

http://www.alibaba.com/product/si10...X_electric_motor_up_to_50kW_weight_11kg_.html
roman's brought the minimum order quantity down to 5, on there...

http://www.tradekey.com/product_view/id/1119836.htm
... and down to 2 MOQ on here 

please don't all crowd him at once - the windings on these out-runner motors are little buggers to build: it's very time-consuming (see the newly-renamed company page for PML Flightlink who split into two and are still going strong - http://www.printedmotorworks.com/in-wheel-motors/ )

l.


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## IamIan (Mar 29, 2009)

FYI ... I see a minimum order of 1... Price by request.
http://www.alibaba.com/product/si10...X_electric_motor_up_to_50kW_weight_11kg_.html


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## gor (Nov 25, 2009)

IamIan said:


> FYI ... I see a minimum order of 1... Price by request.
> http://www.alibaba.com/product/si10...X_electric_motor_up_to_50kW_weight_11kg_.html


quote from ES 
"Motors are 2590 Euro each, and the PikTronic controller is recommended (as testing has proven it capable) but costs 3790 Euro. Ouch!"
http://endless-sphere.com/forums/download/file.php?id=60492&sid=b42a14f475ea108e40eac7f4280f85cf&mode=view
-what eur/usd now? $/kg, $/kw ? (i'm too lazy to look : (((((


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## iti_uk (Oct 24, 2011)

Wow, the liquid-cooled option would be perfect for my future project.

I wonder if the price will come down over the next year or so...

Chris

Update:

I requested a price list (attached). If I were to go ahead with my 4-motor design, that would come out as;

4 motors + liquid cooling = 10,360 EUR
4 controllers = 15,560 EUR

There's also the encoder/resolver plus other odds and ends, but that 25,920Euro number immediately puts it well outside my price range!

25,920 EUR = 34,849 USD = 22,294 GBP



Perfect though this motor would be for my application, I think for now I'll have to look elsewhere.

Chris


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## e_abuzer (Jan 10, 2012)

lkcl said:


> because i can guess, with a high degree of confidence, that it's an LRK TorqueMax design (and i can see it's an "out-runner" from the engineering diagrams on the web site), i have confidence in this motor because although it is unusual i understand it.
> 
> so yes i am planning to use this in a car - not as wheel hub motors but as connected to a standard 4-speed or 5-speed transmission.
> 
> ...


lkcl; How would this motor drive a 1250kg car down the road? Say with the controller they 're suggesting? (Range/speed)
They also mention that you can double the motors and control with 1 piktronik... 
CB..


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## RoughRider (Aug 14, 2008)

this axial flux motors always look good on the papers...

there are many of them outthere...such as Agni or Apex or...

they get the good numbers for torque and power only at very high Voltage...over 400VDC

they also are not waterproof...so, water and dirt can get into the motor and damage it...

This emrax needs 12l/min of watter cooling flow @ 20°C to get its power numbers...that is alot of cooling and at very low temp of only 20°C(not very realistic conditions for a car or motorcycle)


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## IamIan (Mar 29, 2009)

RoughRider said:


> This emrax needs 12l/sec of watter cooling flow @ 20°C to get its power numbers...that is alot of cooling and at very low temp of only 20°C(not very realistic conditions for a car or motorcycle)


where did you see 12 l/sec ????

The spec I see listed on the top of this thread and on their web site is 0.2 l/sec.


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## RoughRider (Aug 14, 2008)

You are right...

it should be 12l/min...


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## IamIan (Mar 29, 2009)

RoughRider said:


> You are right...
> 
> it should be 12l/min...


Do you think 12 L / Min is unusually high or difficult rate of flow for a vehicle's engine/motor coolant system?


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## iti_uk (Oct 24, 2011)

IamIan said:


> Do you think 12 L / Min is unusually high or difficult rate of flow for a vehicle's engine/motor coolant system?


200cc/sec... not too bad.


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## RoughRider (Aug 14, 2008)

i have seen motors with 6-8liters/min...

so...yes 12l/min seams high to me...


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## iti_uk (Oct 24, 2011)

115 L/min water pump.

I guess as long as the cooling jacket chanels aren't too restrictive, 115 L/min would just about cover the 12 L/min requirement... 

There's even an 80 L/min one for those who like to live on the edge.

Chris


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## IamIan (Mar 29, 2009)

RoughRider said:


> i have seen motors with 6-8liters/min...


Which motor are you thinking of?

Is it otherwise competitive with this one in terms of power output and motor weight?


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## arbartz (Sep 27, 2013)

So I know this is a bit of an old thread, but I just heard about these motors and they seem perfect for my application. That being the Formula Hybrid car. I was searching around for a powerful hub mountable motor and a member on this forum suggested these motors. 

I would like to have a system with two hub motors up front and one larger motor in the rear coupled in parallel with our 250cc engine. Given the limitations in battery power by SAE for our competition I have determined that the best configuration we could get would be a 96V system. I'd be using Headway batteries and could provide 560A continuously, with a 1400A burst. So that would give me 53.76kW or up to 134.4kW of power to play with. 

Since this thread started, is there any new information or testing done by any of you? If so, do you guys think this would be a good motor for my application? 

Thanks!


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## lkcl (Sep 16, 2011)

http://www.enstroj.si/Electric-products/emrax-228-motorsgen.html

looks like they are still going, and apparently are working with audi on an electric version of the tt, in their transmissions.

arbatz... i know the common wisdom is to use wheel hub motors but please consider that the common wisdom is fundamentally flawed for dozens of extremely good and quite technical reasons.

the simplest explanation is that electric motors are *NOT* efficient (throughout their entire power band), they simply have DIFFERENT efficiency characteristics [from combustion engines].

in other words what you need to do - if you want something that is going to be both reliable, simple, drivable and also be efficient enough to stand a chance of winning the race, you want to look at the drive-train of the Volvo XL1 Concept Car and copy it pretty much verbatim as best you can [afford].

the volvo XL1 concept car basically uses a triple clutch arrangement to put *either* the electric motor *or* the [500cc diesel] combustion engine *or both* into play, depending on both efficiency and performance demands at the time. they also have an *eight* stage automatic gearbox - automatic because the computer-control selects the most efficient options and you need computer control (really) to do that.

also what's nice about using a triple clutch arrangement is that you can drop the starter-motor entirely, because you can engage the clutches between the two motors and jump-start the combustion engine.

that advice just saved you weight.

reducing vehicle weight in a race environment is *important*.

anyway if you would like my help further please do contact me directly i'll be happy to help you out as it'd be kinda cool - i'm an embedded systems programmer amongst other things.


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## arbartz (Sep 27, 2013)

Thanks for the response lkcl! I'd certainly be interested in speaking with you further about this project.


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## IamIan (Mar 29, 2009)

arbartz said:


> I was searching around for a powerful hub mountable motor
> 
> If so, do you guys think this would be a good motor for my application?


The abuse a hub motor sees ... is something to carefully look at , if you are seriously considering that option ... The wheel environment is one of the most abusive in/on the vehicle ... temperature extremes , exposure to water and other external elements , shock vibrations (potholes) , etc... etc.

Doable .. and there are pros ... but you should also be honest with yourself about the cons as well.


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## lkcl (Sep 16, 2011)

IamIan said:


> The abuse a hub motor sees ... is something to carefully look at , if you are seriously considering that option ... The wheel environment is one of the most abusive in/on the vehicle ... temperature extremes , exposure to water and other external elements , shock vibrations (potholes) , etc... etc.


 effect on the weight of the wheel (drastic increase), increase in moment of inertia making it harder to speed up / speed down, increased gyroscopic effects - the list goes on and on and it's only in things like low weight low cost vehicles such as bicycles or scooters... [and even then only when there aren't any hills because on a hill you will be operating pretty much 100% within the stall torque range - the most inefficient and most overheating range]... that you should even remotely contemplate doing in-wheel motors.

i used to think in-wheel motors were such a fantastic idea... they _would_ be... if you could (a) build in a gearbox and (c) decouple the factors above from the actual wheel.

i think it was peugeot / citroen who did a research project to have active dampers which reacted 2,500 times a *second* to make the wheel move up and down in response to the road and the conditions, just to compensate for the extra weight of the motor. this is both insane and extreme, and in completely the wrong direction of the whole "mass decompounding" advantages that in-wheel motors are *supposed* to bring!!

bottom line: if you ever hear of anyone saying "i got a great idea! nothing you can say will make me change my mind! i'm gonna do a 4 wheel vehicle with in-wheel motors!" then smile politely, back away, and run like stink as soon as you get out of sight


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## lkcl (Sep 16, 2011)

arbartz said:


> Thanks for the response lkcl! I'd certainly be interested in speaking with you further about this project.


i mailed you though diyecar messaging system.


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## Karter2 (Nov 17, 2011)

lkcl said:


> .. i know the common wisdom is to use wheel hub motors but please consider that the common wisdom is fundamentally flawed for dozens of extremely good and quite technical reasons.-.....
> ..... if you want something that is going to be both reliable, simple, drivable and also be efficient enough to stand a chance of winning the race.


 so you dont think hub motors are up to the job then ?....
http://www.diyelectriccar.com/forums/showthread.php/ev-sets-0-60-record-130362.html


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## lkcl (Sep 16, 2011)

Karter2 said:


> so you dont think hub motors are up to the job then ?....
> http://www.diyelectriccar.com/forums/showthread.php/ev-sets-0-60-record-130362.html


look at the actual article; read what they wrote.

"Driven through an integrated planetary gearbox, the cars four individual AMZ M4 wheel hub motors produce 37 kW (50 hp), transmitting a tire-shredding 1630 Nm (1200 ft-lb) of total torque at the wheels."

it's *NOT* direct-drive. they used INTEGRATED PLANETARY GEARBOXES. that immediately solves the problem associated with direct-drive wheel hub motors running in their most inefficient stall-torque range.

also the entire vehicle - including wheels - is only 168kg - so they don't need excessively-heavy motors. and, because they do not need excessively-heavy motors they have been able to get away with all-carbon-fibre rims.

so that is how they deal with the usual problem of high inertia which can end up smashing the wheel and destroying it (or losing traction because the wheel is too heavy to get back down on the ground in a reasonable time) just by going over a small bump.

so, precisely as i just said only yesterday, they deployed an appropriate technical solution which solves the issues inherent with in-wheel motors.

but... carbon-fibre rims? is that commercially viable, do you think? perhaps when volvo's new mass-volume carbon fibre manufacturing technique is more widely commercially available: yeah. then all that is left is to convince car manufacturers to create vehicles that are 1/5th of the weight that they are now. just like the latest micro-cars.


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## IamIan (Mar 29, 2009)

lkcl said:


> they deployed an appropriate technical solution which solves the issues inherent with in-wheel motors.


And kept the pros inherent with in-wheel motors .. sound like a win win for that application.

As in any good design .. in the end of an honest examination of both pros and cons .. pick the right tool for that job / application .. sometimes that will be wheel motors , sometimes it isn't.


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## dcb (Dec 5, 2009)

IamIan said:


> And kept the pros inherent with in-wheel motors ...


I'm not exactly familiar with those, so this is what I came up with, let me know what I missed.

pros: potential space savings, potential weight savings.

cons: multi-motor control complications (weight, $$, space), reduced gearing options, more unsprung weight (handling), more weight at the extremes (harder to change direction, and harder to stop changing direction). Reduced motor configuration optimization options (length/diameter/rpm). Harsh environment. Flexing and more exposed high voltage connections. Typically less efficient.


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## IamIan (Mar 29, 2009)

dcb said:


> I'm not exactly familiar with those, so this is what I came up with, let me know what I missed.
> 
> pros:
> 
> ...


See my Comments on the above in Red (I added some formatting as well , intended for clarity.)


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## dcb (Dec 5, 2009)

I'm just trying to understand what an honest comparison looks like, not trying to trump up anything, the way I see it yaw inertia is a different concern than unsprung weight though, as is additional gyroscopic forces on the suspension/steering.

And if it has planetary gears, well you've got multiple transmissions that are unsprung too.

For strictly performance purposes, it seems when the weight of all that is less than ~1/2 the weight of an axle shaft of equivalent power capability, then it starts to makes sense. Is my thinking wrong there? I am assuming that if a wheel motor can be thusly reduced in weight, so can an inboard motor here.


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## IamIan (Mar 29, 2009)

dcb said:


> I'm just trying to understand what an honest comparison looks like


As much apples to apples as is possible.

If your goal is Lowest $ for __ performance (acceleration,range, etc) ... than compare the specs of specific components and you have your honest comparison.

If instead your goal is most usable space in a given vehicle frame ... then you again look at the specs of specific components and you have your honest comparison.

Most people in the real world have a priority list ... 1 more than 2 .. but 2 more than 3 ... etc ... there are numerous cases in the Real World of engineers who have chosen to use or not use wheel-motors depending on the specifics of their application ... sometimes the pros out weigh the cons ... and sometimes the cons outweigh the pros.



dcb said:


> not trying to trump up anything,


 I for one did not think you were 'trying to tump up anything'.

Sorry , if I gave that impression somehow ... anyway ...



dcb said:


> the way I see it yaw inertia is a different concern than unsprung weight though, as is additional gyroscopic forces on the suspension/steering.


Different yes ... but not a different con item... it just pointing out some of the many different effects of the additional unsprung mass in the rotating wheel.

Each different aspect of this same (increased wheel mass) is all just the branches of that same one con item of ... increased wheel mass.

At least from my PoV.



dcb said:


> And if it has planetary gears, well you've got multiple transmissions that are unsprung too.


Still the same single con item of additional wheel mass... no matter how many different ways it is brought up... additional wheel mass is a real and significant con ... but it is only one con item.

Like wise I do not give the space saving pro of the wheel motor 5 different pro items ... it is one pro item only... it doesn't matter if there are 5 or 50 different possible benefits one could think of for that space saving advantage.

Also .. as I noted before .. multiple motors is not an inherent aspect of wheel motors ... nor is multiple transmissions.

A proper comparison of types of multiple motors ... if you insist on 4 motors and 4 transmissions ... is to compare the wheel motor version of this ... to the non-wheel motor version that also has 4 motors , and 4 transmissions ... apples to apples... the 4 non-wheel motors combined with 4 non-wheel transmissions ... will almost always use more space and weight than the wheel motor version... The wheel motor version is a Pro for anyone that is doing such a 4 motor and 4 transmission system.

Or compare the total additional weight of a single transmission system that can properly distribute the power from a single central motor ... compared to 2 or 4 wheel motors... depending on if it is to be a 2 wheel drive or 4 wheel drive vehicle... even with 4 smaller transmissions fit inside of each wheel ... you are very likely to be less total weight than a much larger transmission / differential / etc .. that has to move the power supplied from a single central motor to all 4 wheels.



dcb said:


> For strictly performance purposes, it seems when the weight of all that is less than ~1/2 the weight of an axle shaft of equivalent power capability, then it starts to makes sense. Is my thinking wrong there? I am assuming that if a wheel motor can be thusly reduced in weight, so can an inboard motor here.


As soon as it is 1 mg less (not 1/2) ... it has a weight advantage.
As soon as it is 1 mL less ... it has a volume advantage.

The on board (non-wheel) motor requires a transmission in order to get it's shaft to the wheel ... even if it is only a single ratio shaft ... the wheel-motor does not 'require' this .. even if people might have good reason to want one in the wheel ... it is not a requirement and thus not inherent to wheel-motors.

That is automatically space and weight penalty to the non-wheel motor .. a penalty it can't get away from ... it needs the transmission (at least a shaft)... the best the non-wheel motor can hope for .. is it's other pros outweigh this con.

A Wheel motor gives no motor in the engine bay ... a central electric motor in the engine bay consumes that space ... thus it is always at a space penalty... it can't escape this con .. the best it can do is hope it's other pros outweigh this con.

- - - - - - - - -- - - - 

If you wanted a specific kind of comparison.

How about this very crude one , we can pick apart if you like.

Both Option A & B both use the exact same motor ... the Emrax pointed out in their thread... both use two of them... Both options are front wheel drive ... both have the same total electric motor power ... etc.

Option A puts one in each front wheel as two front Wheel-Motors.

Option B puts both together centrally located in the engine bay and then uses a transmission with differential (etc) in order to get the power to the two front wheels.

Option A has the penalty of additional wheel mass ... which is significant... has a penalty for the expensive motor in the harsh wheel environment... which is significant.

Option B has the penalty of all the space and weight lost to the transmission system to distribute the motor power to the wheels ... and it also looses additional space in the engine bay to the two motors themselves.

Both have pros and cons ... what is more important will depend on the application preferences.


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## Karter2 (Nov 17, 2011)

lkcl said:


> .
> bottom line: if you ever hear of anyone saying "i got a great idea! nothing you can say will make me change my mind! i'm gonna do a 4 wheel vehicle with in-wheel motors!" then smile politely, back away, and run like stink as soon as you get out of sight


Well, that comment was more than a little off base for the proposed project ......which has been proven to be very well served by "in wheel motors" !
Splitting hairs over detail like direct drive or integrated gearing does little to cover up rash comments !
As Ian explained very eloquently, ..it's "different horses for different courses".


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## dcb (Dec 5, 2009)

IamIan said:


> Both have pros and cons ... what is more important will depend on the application preferences.


That is why I qualified it for performance (i.e. formula). If you want a utility box then space is a key driver. But formula usually is all central, since the driver has to punch a hole in the air anyway, everything is crammed into the center tunnel in front and behind the driver (plus major handling concerns).

I agree there is a right choice for a right application, the question is what application?

I guess I keep the effects of outboarding separate too because that is the result, regardless of the cause. Another one of which is torsion must be handled at the extremes with hub motors, which also adds to the weight of the suspension and mountings (though unless you have inboard disks, you still better be prepared for some torsion at the wheels). Plus whatever suspension changes are needed to get the additional weight to handle better.

So, just trying to see if hubs are hype (worlds fastest 0-60?!?) or what I'm missing, in a formula type car setting that is (where even expense isn't a major consideration, and there is adequate space inboard, and handling is key, and the weight of a driveshaft is about negligible all told, a wash with a fair bit of extra cabling (+losses) and perhaps cooling lines and etc (less power per weight because the motors have to be a certain size?).

I guess my pattern recognition is going off here, that there is a "modularity" bias at work, and some wishful thinking as a result. But modular and optimized are often at odds.


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## IamIan (Mar 29, 2009)

dcb said:


> everything is crammed into the center tunnel in front and behind the driver (plus major handling concerns).


You have two separate issues there to consider the pros and cons of.

Handling .. Sudden changes would be a con for Wheel-Motor.

But .. Batteries can often be crammed into a tight space with far more shape flexibility than gear boxes and drive shafts , etc... If you put the motor central you just removed / displaced batteries .. if you put the gearbox / shaft / differential / etc central you also removed / displaced batteries... and BEV batteries eat both space and weight... for a 'performance' vehicle the location of that large volume of heavy battery will be a major effect on final vehicle performance.



dcb said:


> I agree there is a right choice for a right application, the question is what application?


Exactly ... there are several applications that a Wheel motor is the right tool for the job ... others' it is not... it has both pros and cons.



dcb said:


> So, just trying to see if hubs are hype (worlds fastest 0-60?!?) or what I'm missing


If that 'worlds fastest 0-60' is your only goal .. with no other mitigating factors (like , cost, turns, bumps, etc) Wheel-Motors beat the other type of option (central motor+gears+differentials+shaft+) .. it's that simple.



dcb said:


> In a formula type car setting


Unfortunately that isn't specific enough .. as outlined above .. they will have some pros for that setting .. but also have cons... 

You don't get your cake and eat it to .. you may want both , or all of the above .. but you have to choose which is more important , and by how much.

All those things you listed ... you have to prioritize them more ... is more laps per pit stop 5% or 10% more valuable than 0.1G sharper handling turn .. is the greater wheel mass worse than the less centralized battery mass (on the vehicle) , and by how much compared to other priorities... how much more important is that 0-60 time? ... etc.


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## dcb (Dec 5, 2009)

IamIan said:


> If that 'worlds fastest 0-60' is your only goal .. with no other mitigating factors (like , cost, turns, bumps, etc) Wheel-Motors beat the other type of option (central motor+gears+differentials+shaft+) .. it's that simple.


But, a hub motor car made that claim, and it was patently false, that was my point. That record is most definitely held by a dragster shaped car (another case of form follows function), not a car with an overly heavy front end and limited traction.

Of course inboard doesn't *require* any more gearing/differential than an outboard, especially in a locked rear axle dragster, though there isn't a lot of room for a motor between the wheels there.

So the 0-60 comment was me making the point that the remarkable claims are already coming false and hype laden.

There are always going to be economies of scale, where one large motor (or two even) simply works better than 4 small ones. It's that simple  If you can get all the weight on the back two wheels, then you don't need the complications additional weight of powering the front wheels. The front motors would necessarily be a smaller size for the reduced power they can deliver, it gets ugly when you try to optimize it as you have to change motors at that point to get the right weight for power delivered per axle (which reduces the power you can deliver because it weighs less).

Likewise the formula cars have very light wheels and suspension (and have even dabbled with inboard brakes). The gains from losing the axle shafts vs having uber-light wheels and central mass (and both have some gearing)? 

The answer for formula racing seems obvious to me, but the world needs its experiments I guess.

edit: according to this, "full sized" formula wheels are estimated to be ~2.8kg http://www.f1technical.net/forum/viewtopic.php?f=6&t=14213


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## IamIan (Mar 29, 2009)

dcb said:


> But, a hub motor car made that claim, and it was patently false,


What any one specific person or group or vehicle claimed or failed to do has no impact on the pro and con points I already pointed out.

Also I seriously doubt any actual group or car made such a claim ... I seriously doubt 0-60 time was ever the ONLY consideration .. which was the context of that comment that I made.

If you think otherwise .. please site your specific example.



dcb said:


> That record is most definitely held by a dragster shaped car


Either type in-wheel or non-wheel can have the same shape ... thus this point is irrelevant.



dcb said:


> Of course inboard doesn't *require* any more gearing/differential than an outboard,


False .. it needs at the very minimum a direct shaft and some angle adjusting gears... to get power from the central motor to the wheel.



dcb said:


> especially in a locked rear axle dragster, though there isn't a lot of room for a motor between the wheels there.


exactly ... the volume and weight of the axle itself (and its pieces) is an automatic con .. a penalty that the in-wheel does not have.



dcb said:


> There are always going to be economies of scale, where one large motor (or two even) simply works better than 4 small ones. It's that simple


Not 'always' ... as has already been pointed out .. and it isn't always beneficial either ... there is a maximum torque point ... if you had 1 billion kw of power ... no wheel has enough friction for a 100 kg vehicle will make use of it.



dcb said:


> If you can get all the weight on the back two wheels, then you don't need the complications additional weight of powering the front wheels.


which is achievable by either type ... 2 rear wheel motor or non-wheel motor + transmission .

And if you insist on a 4 four wheel drive for one ... than keep it apples to apples comparison and do the same for the other.



dcb said:


> The gains from losing the axle shafts vs having uber-light wheels and central mass (and both have some gearing)?


exactly .. you have to compare .. losing the space and weight of the axels and such is a Pro ... don't throw it away due to personal bias .. gaining mass in the wheel is a con ... don't throw it away due to personal bias... they oppose each other... there is no one always is better solution.



dcb said:


> The answer for formula racing seems obvious to me, but the world needs its experiments I guess.


Look closer .. remove the bias glasses ... there are pros and cons either way... once specific details of priorities are set ... X 5% more than Y .. G 1% more than X , etc ... than a winner eventually emerges.


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## dcb (Dec 5, 2009)

I don't think you have quite got the whole picture here...

There are "official" claims being made in the otherwise unqualified "fastest acceleration electric car" category.

http://www.guinnessworldrecords.com/world-records/6000/fastest-0-100-kmh-acceleration-electric-car

Building a formula car should be about engineering, not wishful thinking. To make a statement that "hubs are always going to be faster" is also wrong, because of countless issues, many of which have been stated here. I'm not sure if unsprung weigh in a dragster makes much difference, I only bring that up because that is the sort of shape you should expect to see when making an acceleration claim, and not seeing it should rightly make you question it. And technically a dual shaft motor with a wheel on each side still isn't a hub motor (nor is a pivoting inboard motor).

In a formula car you see another pattern, designed for lots of twisties, a bit of straightaway, bumpy chicanes, changing track conditions. Space is a consideration, but not the primary one. There are a lot of yawing, and bumping going on (and a myriad of other hub issues no-one is thinking about, i.e. gyroscopic forces at high speed). I cannot fathom how you think it is likely that formula racing is a good application of hubs, or even be willing to agree that it doesn't seem to make sense, but lets see how they do anyway?


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## IamIan (Mar 29, 2009)

dcb said:


> There are "official" claims being made in the otherwise unqualified "fastest acceleration electric car" category.
> 
> http://www.guinnessworldrecords.com/world-records/6000/fastest-0-100-kmh-acceleration-electric-car


That example is VERY VERY VERY far away from the ... "0-60 ONLY Goal" category referenced before.



dcb said:


> Building a formula car should be about engineering, not wishful thinking.


Agreed .. that's why I keep saying to weigh the pros and cons .. no amount of wishful thinking makes the cons go away nor the pros go away... There is no one size fits all , no matter how much one wishes for it ... it is not always wheel-motor ... it is not never wheel-motor ... the details define which pros and which cons end up mattering more in the final analysis.



dcb said:


> To make a statement that "hubs are always going to be faster" is also wrong, because of countless issues, many of which have been stated here.


Who are you quoting ??

I would certainly disagree with that quote as well... as I've repeated numerous times ... both have pros and cons .. you define the priorities and details of a specific context and weigh the options.



dcb said:


> I'm not sure if unsprung weigh in a dragster makes much difference, I only bring that up because that is the sort of shape you should expect to see when making an acceleration claim, and not seeing it should rightly make you question it.


Vehicle shape is still irrelevant.
Either path ... Wheel-Motor ... or ... Non-Wheel-Motor ... either one can have that shape of vehicle ... thus the shape of the vehicle is still irrelevant to this discussion about wheel motors.



dcb said:


> And technically a dual shaft motor with a wheel on each side still isn't a hub motor (nor is a pivoting inboard motor).


Who ever said it was?



dcb said:


> I cannot fathom how you think it is likely that formula racing is a good application of hubs, or even be willing to agree that it doesn't seem to make sense, but lets see how they do anyway?


When did I ever make this claim ?

I've been very consistent in repeatedly posting what I think ... but here ... have it again ... both have pros and cons ... define the specific details and priorities of a specific context ... and then weigh the pros and cons ... in order to see which option is the best fit in that case.


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## dcb (Dec 5, 2009)

IamIan said:


> Agreed .. that's why I keep saying to weigh the pros and cons


And that is exactly what I'm trying to do here. When I do, you say "you have to weigh the pro's and cons".

One thing though (thinking about formula cars, but others too), I wouldnt be too quick to dismiss having a multi-speed gearbox in EV's as a con, sure the weight/friction is, but attaining peak system power or efficiency at a variety of vehicle speeds is a big plus, for not a lot of weight or loss. To truly compare it you have to increase the size/weight of a hub system to match the performance.

Indeed the Formula E cars come with a 5 speed synchronous shift (lots of changes in vehicle speed).


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## IamIan (Mar 29, 2009)

dcb said:


> And that is exactly what I'm trying to do here. When I do, you say "you have to weigh the pro's and cons".


#1> Because weigh the pros and cons .. is my position on this... there is no one single option that is the best fit for all possible situations ... I've been consistent in this PoV ... sometimes Wheel-Motors are better ... sometimes they are worse... it seems to me like you are trying to insist on a single winner .. one that will always be better ... and so far you seem to be heavily biased anti-wheel-motor .. I don't agree with the one winner (it incorrect) , or the bias (it's counter-productive).

#2> 0-60 'only' has different pros and cons ... it drives a nearly straight line ... and has very different pros and cons from anything that needs 'handling' (sharp turns) ... both of those are also completely different pros and cons from street cars ... and all three of those are different pros and cons Formula E series races ... different for off road BEVs .. etc ... etc ... every time you shift to a different context ... you change the priorities and the pros and cons.

#3> Even if you stay in one specific field ... say a 0-60 'Only' goal .. there too there are different paths and methods that each have different pros and cons... The Emrax (topic of this thread) .. is one type of option .. there are others ... it can be used a variety of different ways in-wheel with gears , in-wheel without-gears , direct drive , belt drive , planetary gear, etc ... etc.



dcb said:


> One thing though (thinking about formula cars, but others too), I wouldnt be too quick to dismiss having a multi-speed gearbox in EV's as a con, sure the weight/friction is, but attaining peak system power or efficiency at a variety of vehicle speeds is a big plus, for not a lot of weight or loss.


Who is dismissing having a multi-speed gearbox in a EV ??

I don't recall anyone asking , or even suggesting to 'dismiss' it ???

I for one have consistently and repeatedly ... you know what's coming next ... said to weigh the pros and cons .. nothing is just being 'dismissed'.


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## dcb (Dec 5, 2009)

IamIan said:


> And kept the pros inherent with in-wheel motors .. sound like a win win for that application.
> 
> As in any good design .. in the end of an honest examination of both pros and cons .. pick the right tool for that job / application .. sometimes that will be wheel motors , sometimes it isn't.


Which was a response to the "record breaking" formula SAE car discussion, which is where I chimed in...
http://www.diyelectriccar.com/forums/showthread.php/ev-sets-0-60-record-130362.html


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## dcb (Dec 5, 2009)

IamIan said:


> If that 'worlds fastest 0-60' is your only goal .. with no other mitigating factors (like , cost, turns, bumps, etc) Wheel-Motors beat the other type of option (central motor+gears+differentials+shaft+) .. it's that simple.


I think that is not remotely conclusive, and you are dismissing all gears here (i.e. multi speed transmission) and ignoring the constraints put on the motor size/configuration by the wheel.

And of course the main objection is that this isn't the fastest 0-60 electric vehicle, just look at the NEDRA site and do a mote of interpolation (and they aren't hub motor vehicles coincidently), and they don't look like formula cars (which are designed for a different purpose and are likely never to be the fastest form for a drag race).


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## Duncan (Dec 8, 2008)

Hi dcb
IMHO while there is something in the "Horses for courses" argument about the only time that hubmotors have proven their worth
(For small machines anyway - in really big trucks (400tonne) they are very common)
Is in this
https://www.hq.nasa.gov/alsj/LRV_OpsNAS8-25145.pdf


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## dcb (Dec 5, 2009)

That's a good use, stuff has to be small/light as possible on a ship, and the wheels can turn farther than with a shaft. That is very much a utility vehicle. The ability to have a smaller turning radius *could* be a factor in a 4wd formula race if there are enough hairpins, formula sae is a fairly low speed race (avg 35mph top 60mpg ish), guess time will tell.


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## IamIan (Mar 29, 2009)

dcb said:


> IamIan said:
> 
> 
> > If that 'worlds fastest 0-60' is your only goal .. with no other mitigating factors (like , cost, turns, bumps, etc) Wheel-Motors beat the other type of option (central motor+gears+differentials+shaft+) .. it's that simple.
> ...


I never said I was dismissing gears , wheel constraints , etc... and I wasn't .. I weighed the pros and cons for that narrow context .. I am happy to go through it step by step .. and I am very certain , in the end you will agree ... I suspect you will just not like the answer .. more than likely dismiss it as being the useless context that it actually is ... oh well.

Ok .. so here forward this context is ONLY :

*"World's Fastest 0-60 Wheel-Driven vehicle ONLY goal -- No other mitigating factors."
*
No shifting contexts , no substitute contexts , etc.

And yes it is conclusive... although it's (in my opinion) a silly and nearly useless context ... but we have to agree on one specific context in order to make any progress ... the shifting and changing is counterproductive.

I'll start off giving you some hints to help get you in the right frame of mind ... and if you like we can then continue step by step.

#1> By 'Wheel-Driven' .. A central motor and transmission could still be used ... but I wanted make it clear the context was not about things like rocket propelled vehicles... which originally was an unwritten assumption I made in the initial statement you quoted .. I wanted it clean and clear here , so I included it.

#2> That one example = meaningless .. it is does not fit into this narrowly defined single context.

#3> NERDA = meaningless ... Formula (any series) = Meaningless ... Complying with NERDA or any formula series rules is not a requirement for this narrow specifically defined context... there is one and ONLY one goal in this narrow context.

#4> Sense that is the ONLY goal .. we can spend any amount of $ we wish ... if it were to cost $100 Trillion dollars for a single use vehicle .. that is perfectly fine .. because $ is not a factor .. in this narrow specifically defined context.

#5> Because that is the ONLY goal with no other mitigating factors .. I can cherry pick everything in order to achieve that one and only goal .. A custom 'road' sure , custom tires made of anything I want sure , custom picked driver sure , etc...etc... Anything that would shave time off that 0-60 time.

- - - - - 
Now I think that should clearly set the context and help with the frame of mind.

If you want to shift to a different context .. than the priorities , pros, and cons will change... and with them the results might change .. the wheel motor will not always be the right tool for all possible contexts (as I've been stating very consistently).

If you wish ... with this narrowly defined specific context in mind .. we can go through step by step how the pros and cons weighed out , will come to that result... as useless as , such a narrow context, is.


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## IamIan (Mar 29, 2009)

Duncan said:


> Hi dcb
> IMHO while there is something in the "Horses for courses" argument about the only time that hubmotors have proven their worth
> (For small machines anyway - in really big trucks (400tonne) they are very common)
> Is in this
> https://www.hq.nasa.gov/alsj/LRV_OpsNAS8-25145.pdf


Excellent example 



dcb said:


> That's a good use, stuff has to be small/light as possible on a ship, and the wheels can turn farther than with a shaft. That is very much a utility vehicle.



A context with pros and cons that favors a wheel motor.
Who are you .. and what did you do with the wheel-motor bashing dcb ??  (I jest in case you can't tell)


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## dcb (Dec 5, 2009)

I was trying to think of a good application (space more important than high speed performance aka racing), and duncan presented one. I was thinking maybe a self propelled crate in a factory, or maybe some science fair project powered by a palm-pilot 

re: context, I think what you are *trying* to get at is simply a=f/m (and multiple gear ratios can mean a lot more f on average, just saying, especially if we are getting into unobtanium). And there *may* be additional weight with inboard (though you seem to be ignoring the planetary gears in the hub), but if you have superconducting motor leads, then I can have impossibly light half shafts (single use?). But of course the wheels themselves ARE a constraint, for you. And you didn't say anything about power levels so I can always cherry pick a larger motor and/or a smaller tire with less weight and rotational inertia


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## Karter2 (Nov 17, 2011)

dcb said:


> I was trying to think of a good application (space more important than high speed performance aka racing), and duncan presented one. I was thinking maybe a self propelled crate in a factory, or maybe some science fair project powered by a palm-pilot


How about a bicycle wheel hub motor ?...
...there are a few million of those running around already !


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## dcb (Dec 5, 2009)

Karter2 said:


> How about a bicycle wheel hub motor ?...
> ...there are a few million of those running around already !


Yup, plus it has the added benefit of helping to prevent you from turning in the direction you want to go  (even when it isn't providing power)


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## Karter2 (Nov 17, 2011)

dcb said:


> Yup, plus it has the added benefit of helping to prevent you from turning in the direction you want to go  (even when it isn't providing power)


.?? You will have to explain that a little ?
If you are thinking of the gyroscopic effect of the motor mass, you may have an exaggerated imagination.


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## dcb (Dec 5, 2009)

It is exactly gyroscopic effect, unless hub motors can magically defy physics too. Not saying it is huge (though it can be more annoying to scary on the front).


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## IamIan (Mar 29, 2009)

dcb said:


> re: context, I think what you are *trying* to get at is simply a=f/m (and multiple gear ratios can mean a lot more f on average,


Almost .. not just F=ma .. but sure let's start there... then just for the basic starters ... add in momentum... we'll keep it as simple as those two for now.

Gears , shafts , etc .. all have mass ... which is an automatic momentum penalty / con.

Gears add nothing .. they reduce net power and energy output .. none are 100% efficient .. the output power and energy is always less than the input power and energy.

You might be tempted to think that the trade off of more RPMs on input to more torque on output will compensate .. but in this context of 'only' it doesn't work .. that only works in other (more limited) contexts. (see additional bellow)



dcb said:


> And there *may* be additional weight with inboard (though you seem to be ignoring the planetary gears in the hub),


Not ignoring .. I don't know why you keep repeatedly making this same error .. I'm weighing the pros and cons ... and in this 'only' context .. I'm not going to use any gears in the hub .. the cons ... in this context .. outweigh the pros of doing so.

Any use of gear , shafts, etc by the central motor ... which is has to use to connect to the wheel ... is always going to be a mass penalty .. not maybe .. it is a certainty.



dcb said:


> but if you have superconducting motor leads, then I can have impossibly light half shafts (single use?).


Superconducting motors are 100% completely possible .. only expensive .. your shafts are still limited to the limits of what material science can produce .. even if you have no $ limits .. you have physical limits ... and material strengths have finite limits .. no matter how much $ you spend ... I can exceed those material limits with magnetic field strengths of superconductive motors... and I can do it in a relatively small motor.

The shaft no matter how light ... is still a mass and thus momentum penalty .. and is still less than 100% efficient conversion from input to output ... I do not have to share either such penalty in the wheel-motor .. in this context.



dcb said:


> But of course the wheels themselves ARE a constraint, for you. And you didn't say anything about power levels so I can always cherry pick a larger motor and/or a smaller tire with less weight and rotational inertia


Correct .. the only power limits are physcial limits... what is possible.

At the superconductor levels ... larger motor is a con or penalty ... it doesn't help you any ... it hurts you.

Magnetic field strength decreases with distance ... a larger motor is not automatically more powerful ... especially in this context ... where I can go to the superconductor motor levels.

At the super conductor level the tiny motor has zero resistance ... I can put nearly any arbitrarily large flow of electrical current through a very tiny superconductor motor .. so small ... that there is more than enough space in the wheel for a superconductive motor powerful enough to itself reach the material physical limits ... further power becomes useless.











- - - - - - 

So far ... your version has a heavier vehicle ... with a momentum penalty ... and less total drive output power ... it's in the hole ... and in this narrow (and useless) context .. it won't climb out .. but only go deeper into the hole with further examination of more pros and cons.

The wheel-Motor wins this narrow 0-60 'only' context... it is that simple.


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## dcb (Dec 5, 2009)

I think you might have an EE bias (no suprise here), to think that there are no major advances to be made in materials.

Obviously gears do help in the right circumstance (i.e. when your vehicle isn't making peak power because it isn't yet moving fast enough), but you are talking about approaching infinite power, which means I get infinite power, and infinite power with selectable ratios is more infinite at a variety of speeds, to paraphrase John Green  Pretty much more power available at every vehicle speed except 1. Granted it reduces peak power by a tiny bit, but it allows you to attain more power more often while your speed changes.


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## IamIan (Mar 29, 2009)

dcb said:


> I think you might have an EE bias (no suprise here), to think that there are no major advances to be made in materials.




You'd like to think that wouldn't you 
Incorrect .. That is not what I think... Sense I also never made such a claim ... I do not know where you pulled that false assumption about me from ?
possible future material advances doesn't help enough to make a difference .. materials have finite limits .. no matter what they are made from ... in physics the concept also comes up in discussions involving 'degenerative matter'.
It is not opinion ... it is fact .. that a superconductive cable can transfer more power (electrically) than any possible material could physically tolerate the stress of in the same size and weight... your shaft would have to be larger and heavier than the superconductive cable just to transfer the same power .. thus a size and weight penalty... on top of the less than 100% efficiency penalty in power as well.
Appealing to fictional advances that do not exist .. and may not ever exist .. is useless and counterproductive.
First because if you are dependent on fictional tech ... in order to try and catch up with current real proven tech .. well  .. is all I'll say about that.
Second .. if Fictional advances are allowed .. that's not a one way street .. I can make just as many fictional advances as well ... which thus ends up being completely useless and counterproductive to even go down that at all.
 




dcb said:


> Obviously gears do help in the right circumstance


Just not this one.

They hurt you .. and are a penalty .. in this context.



dcb said:


> but you are talking about approaching infinite power, which means I get infinite power,


Only up to the finite material limits ... which do exist.

Once at that point any further power is useless.

Even if your central motor is also a superconductive motor is can't be any more powerful .. and the losses and finite limits of the shaft and gears put you at a lower net output ... and are heavier.



dcb said:


> Granted it reduces peak power by a tiny bit, but it allows you to attain more power more often while your speed changes.


He admits the loss of max net power output ? ... great ! ... so you have less power to accelerate with.

And you weigh more.

Your still 2 in the hole.

Also ... it will never be able to give more power output ... we are already at the materials physical's limits with both motors .. the smaller and lighter superconductive wheel-motor just doesn't have the additional penalties.


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## dcb (Dec 5, 2009)

IamIan said:


> ...
> He admits the loss of max net power output ? ... great ! ... so you have less power to accelerate with.


Lets return to earth for a little bit, look at a hp (power) graph for a motor, realize that it is rpm dependent, and realize that with direct or fixed gearing that peak power is also speed dependant. With two gears, you get two opportunities to come within/ say, %98 of peak power while building up your speed. More opportunities with more gear ratios. That is to say, you have MORE net power available, except at one speed (but we are accelerating, not one speed).

Besides you still haven't quite explained how, given your motor is made out of materials, you are going to shrink it to nothing to reduce tire mass. I think that is as far fetched as anything. You will possibly increase the efficiency, but size is gonna be a problem for you.

P.S. I win


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## IamIan (Mar 29, 2009)

dcb said:


> Lets return to earth for a little bit, look at a hp (power) graph for a motor, realize that it is rpm dependent, and realize that with direct or fixed gearing that peak power is also speed dependant. With two gears, you get two opportunities to come within/ say, %98 of peak power while building up your speed. More opportunities with more gear ratios.
> 
> Besides you still haven't quite explained how, given your motor is made out of materials, you are going to shrink it to nothing to reduce tire mass. I think that is as far fetched as anything. You will possibly increase the efficiency, but size is gonna be a problem for you.
> 
> P.S. I win


Let's sum up.

There are two motors ... both superconducting equally crazy powerful motors.

You want to loose power going through a less than 100% efficient gear box .. and add additional vehicle weight ... and add time delays needed to shift gears .. and you insist that less final power at the wheel in a heavier vehicle with spending more time to shift ... will some how have a faster acceleration ??? ... best of luck 

- - - - - 

I never claimed my motor would be 'nothing' ... why would you even expect me to explain something I never claimed ??

I also never claimed to reduce tire mass .. so again .. why would you even expect me to explain something I never claimed ??

Although ... I will agree ... all three would be far fetched... both of those you listed and me randomly explaining things I never claimed (and disagree with) ... 

I did already explain the size and weight... did you see how tiny small that 12,500 Amp superconducting cable was in my that posted picture ? 12,500 Amps produces a rather strong magnetic field ... capable of considerable Force .. even at zero RPMs.

Even if superconducting motors paralleled the curve of normal copper motors (like you seem to suggest) ... even if we take that leap .. you still have a % of power loss from gears ... and additional weight penalties from having the gears and shaft.



dcb said:


> P.S. I win


Yes you did .. You proved your bias is far to strong for me to penetrate .. congratulation , I yield to your impregnable bias ..   (it's a joke)


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## dcb (Dec 5, 2009)

but wait, it is standard day conditions, and you forgot to include a 60lb liquid nitrogen generator to keep your less than room temp super conductors cold, and your motors detonated at the start: DNF! 


The explosion blew the wheels completely off. Mine detonated too, but I was able to push it off a 50m cliff to get it up to 60mph FTW! I was then taken to the hospital and pronounced DOA.


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## aeroscott (Jan 5, 2008)

dcb said:


> Lets return to earth for a little bit, look at a hp (power) graph for a motor, realize that it is rpm dependent, and realize that with direct or fixed gearing that peak power is also speed dependant. With two gears, you get two opportunities to come within/ say, %98 of peak power while building up your speed. More opportunities with more gear ratios. That is to say, you have MORE net power available, except at one speed (but we are accelerating, not one speed).
> 
> Besides you still haven't quite explained how, given your motor is made out of materials, you are going to shrink it to nothing to reduce tire mass. I think that is as far fetched as anything. You will possibly increase the efficiency, but size is gonna be a problem for you.
> 
> P.S. I win


 How does your graph from a conventional motor relate to a super conducting motors performance . The fields are huge , no iron core to saturate, just back iron (around the outside of the motor). conventional 
motors need more field at low rpm , so more amps are needed (less eff.) as speed is increased less amps or more torque (higher eff.) . 
The superconducting motor has much higher eff. over its range . If higher eff. at higher speed the gains are going to be small.ie The closer you get to 100% the smaller the gains.


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## dcb (Dec 5, 2009)

Well given that room temp super conductors don't exist (and I can't make up imaginary materials either), you do need to account for on-board cooling too. But since he isn't declaring that the lower limit for this imaginary motor is a singularity, then we are well into "it depends" land, certainly not into "hub motor wins, it's that simple" land. Plus I don't know of superconducting batteries or BJTs.


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## Duncan (Dec 8, 2008)

If you leave superconducting motors out of the equation
(Not YET ready for us amateurs)
Then the reason for reduction gearing is simple
Motor torque is roughly proportional to weight

A motor plus a 4:1 gearbox is lighter than a motor capable of producing four times the torque


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## dcb (Dec 5, 2009)

That is true, but you are trading rpm for torque (plus a bit of loss) and not actually increasing power (depending on vehicle speed), and power is torque * rpm. If you have more power, you can make more torque for the same rpm (or more rpm for the same torque).


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## aeroscott (Jan 5, 2008)

If the motor has been reduced 100 times but torque remains the same . The gear box will be huge compared to the motor.


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## dcb (Dec 5, 2009)

Don't worry, there are tiny yet huge power gearboxes right around the corner  They are made 1 atom at a time.


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## Duncan (Dec 8, 2008)

dcb said:


> That is true, but you are trading rpm for torque (plus a bit of loss) and not actually increasing power (depending on vehicle speed), and power is torque * rpm. If you have more power, you can make more torque for the same rpm (or more rpm for the same torque).


Only true with a gearbox - then you can select the rpm and torque

With a motor you get a maximum amount of torque roughly related to the mass of the motor
And that is limited - want more torque - need more motor


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## Duncan (Dec 8, 2008)

aeroscott said:


> If the motor has been reduced 100 times but torque remains the same . The gear box will be huge compared to the motor.



The limiting factor will be the output torque - so the output will be a fixed size.

If you only need a low speed then it makes sense to use a small motor and gear it


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## dcb (Dec 5, 2009)

Duncan said:


> If you only need a low speed then it makes sense to use a small motor and gear it


Generally agree, small motor = low speed. Though there is some downsizing of motors going on thanks to more liquid cooling going on.


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## Duncan (Dec 8, 2008)

dcb said:


> Generally agree, small motor = low speed. Though there is some downsizing of motors going on thanks to more liquid cooling going on.


Yep - with liquid cooling you can get more torque/kg

But as you pointed out then you need all of the other cooling paraphernalia

I like the "idea" of hub motors - but in the cruel real world they are rarely a good idea


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## IamIan (Mar 29, 2009)

dcb said:


> but wait, it is standard day conditions, and you forgot to include a 60lb liquid nitrogen generator to keep your less than room temp super conductors cold,





dcb said:


> Well given that room temp super conductors don't exist


Funny ... but you fell again for a classic blunder ... the most famous is never get involved in a land war in Asia ...you again made the error to assume I forgot .. I didn't ... I .. wait for it ... that's right ... I weighed the pros and cons ... I have no such 'standard day' requirements ... I can do this whole thing in any conditions I can possibly fabricate ... and I only need it to stay superconducting for the time period of time needed to accelerate from 0-60 ... 

I can even build the entire track in the cold vacuum of space .. because that is possible ... and I have no $ restrictions.



dcb said:


> Don't worry, there are tiny yet huge power gearboxes right around the corner


Still apealing to fictional technology in hopes that it will let you catch up to existing technology ? .. see previous comments on this approach.

You still have less power at the wheel , have a heavier vehicle , and lost time to gear shifting .. only with those biased rosy glasses on does this not look to be a slower accelerating vehicle. 



Duncan said:


> If you leave superconducting motors out of the equation
> ...
> A motor plus a 4:1 gearbox is lighter than a motor capable of producing four times the torque


yup .. as said previously ... different context = different pros and cons , and very possible to get different results.

and even there ... you have limits ... they don't use giant gear boxes for diesel locomotives to convert torque and RPM from the combustion engine down to the wheels ... such a required gear box would be larger and heavier than skipping it ... so they don't do that ... they use a HEV approach ... even with the additional weight +space+ losses of converting ICE shaft through generator to electrical ... through control electronics ... to a electric motor ... the result is smaller , lighter , and more efficient than what gears could possibly do.

That having been said ...take that concept ... combine it with an Emrax motor (back on topic of this thread) ... as of July 2014 they are up to peaks of 160kw and 450NM of torque out of a 19.9 kg (~44lb) motor... in the Audi conversion Emrax is doing with one of their motors Link .. AFAIK that gear box goes up a max ratio ~13:1 motor to output shaft ... woudl be near a peak of ~5,000 NM is some crazy wheel torque.


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## IamIan (Mar 29, 2009)

Duncan said:


> I like the "idea" of hub motors - but in the cruel real world they are rarely a good idea


Agreed .. although for me not for peak torque or drag times ... I don't need more than ~60kw total vehicle max ... I like the vehicle space savings ... take all the motor and transmission out of the engine bay entirely.

But ... soo expensive a device to be put in such an abusive environment .. that's the killer for me


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## dcb (Dec 5, 2009)

Sorry, standard day conditions, I already called it  And any cooling/heating needs to be suited for continuous operation, you are not gonna pull a smokey yunick on me.


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## dcb (Dec 5, 2009)

oh, and props to your Wallace Shawn imitation


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## IamIan (Mar 29, 2009)

dcb said:


> Sorry, standard day conditions, I already called it  And any cooling/heating needs to be suited for continuous operation, you are not gonna pull a smokey yunick on me.


Nope on both 

Prior to your comments about 'standard day' ... I had already previous called:

*"World's Fastest 0-60 Wheel-Driven vehicle ONLY goal -- No other mitigating factors."
*
Continuous is also not required for me ... I 'only' have the one goal in that context .. I can have a single use device only lasting long enough for the one 0-60 pull *

*Of course you can admit defeat and change to a different context .. *

*


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## dcb (Dec 5, 2009)

I already won, and died from my injuries though?!?


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## IamIan (Mar 29, 2009)

dcb said:


> I already won, and died from my injuries though?!?


My bad


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## IamIan (Mar 29, 2009)

dcb said:


> needs to be suited for *continuous operation*


The full impact of (*Bolded*) It just occurred to me ...  (for funny)

Suited for continuous operation ... sooo that means you can only do the 0-60 acceleration using some continuous energy source ... like solar.

Because you have to be able to have continuous operation ... which itself rules out any option that would not be able to be sustained ... continuously .. sooo you can't stop for refueling ... not after 1 hour .. not after 100 hours .. 1 million hours , etc ... and because this is about the vehicle itself achieving this 0-60 time .. and not being boosted by other vehicles or devices .. you can't even do a kind of 'mid-air' refueling (from some other device).

- - - - -

So given the above ... 'continuous' ... that seems to rule out all vehicle types but the solar racers .. like the GM Sunraycer.


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