Breakthrough e-bike design. Well, maybe not...

General Discussion about electric bicycles.
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EVTodd   10 kW

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Breakthrough e-bike design. Well, maybe not...

Post by EVTodd » Sep 16 2008 11:08pm

Ok... It's not an e-bike but maybe it can give you guys some ideas for outrunner motors. No need to reduce the rpms! LOL :lol:

http://qconlineauction.com/site/view_ad.php?v=237916

I hope no one flips over the bars on that one! Would be easy with all the weight up front.
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Link   100 MW

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Re: Breakthrough e-bike design. Well, maybe not...

Post by Link » Sep 16 2008 11:29pm

LOL

Freakin' awesome. Reminds me of the time I tried a battery powered leaf blower pointed behind me.
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EVTodd   10 kW

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Re: Breakthrough e-bike design. Well, maybe not...

Post by EVTodd » Sep 16 2008 11:37pm

I just noticed this quote too: "you cant get in trouble riding it around on the road in my neighbor so id call it street legal". Too funny.
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My Friction Drive Outrunner Setup: http://endless-sphere.com/forums/viewto ... &start=330

swbluto   100 GW

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Re: Breakthrough e-bike design. Well, maybe not...

Post by swbluto » Sep 17 2008 12:42am

It might be nice having twin motors on the back positioned so the air-flow wouldn't interfere with another "part" of the bike(including the rider), that way self-defeating air resistance wouldn't hurt the useful force the motor provides.

I kind of wonder what the energy efficiency of a propeller based motor system is, assuming optimal placement and propellers. It seems like it could operate at "top efficiency"(or close to there) no matter the velocity of the bike which would seem to be an immediate advantage. Another advantage would be it could be electrified by that 6 HP outrunner(or similar) and part of the air flow being generated could be used to self-cool the outrunner engine(Which is probably the way it was designed for being made for air-planes and the such) which is a significant problem with non-cooled outrunners. Another advantage is the obvious simplicity of it and low maintenance.

Methinks someone is eventually going to try this idea. :!: :mrgreen:

Even if the total conversion efficiency is 75%, 75% of 12 HP is 9 HP. That's some serious acceleration and speed. 8)

A quick http://www.kreuzotter.de/english/espeed.htm calculation puts an estimate of 50-60 mph. Now, if this idea might be so awesome, why hasn't it been exploited by motorcycles? Oh... that's right... the history of batteries and the kind of machinery needed to power propellers with gas. It could also have something to do with the power needed by ICE motorcycles and how the amount of suction created by that much power would seriously interfere with the enjoyability of the ride(And possibly drag down the efficiency factor with higher power requirements/suction). :shock:

I *really* want to try this. But, alas, not enough money. *sigh*
Last edited by swbluto on Sep 17 2008 1:04am, edited 1 time in total.

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Link   100 MW

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Re: Breakthrough e-bike design. Well, maybe not...

Post by Link » Sep 17 2008 1:03am

swbluto wrote:Now, if this idea might be so awesome, why hasn't it been exploited by motorcycles? Oh... that's right... the history of batteries and the kind of machinery needed to power propellers with gas. It could also have something to do with the power needed by ICE motorcycles and how the amount of suction created by that much power would seriously interfere with the enjoyability of the ride(And possibly drag down the efficiency factor with higher power requirements). :shock:
And possibly that someone has tried it and accidentally touched the propeller. :shock:

EDIT: 100MW mark. This deserves cake.

Last edited by Link on Sep 17 2008 3:33am, edited 1 time in total.
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Re: Breakthrough e-bike design. Well, maybe not...

Post by swbluto » Sep 17 2008 1:07am

Link wrote:And possibly that someone has tried it and accidentally touched the propeller. :shock:
Oh well. Sometimes sacrifices needed to be made for improvement.

Mao thought so, anyways. :P

(I think the use of a propeller cage would be... needed... which would increase the air-resistance but I don't think it should hurt the efficiency too much.)

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diver   1 kW

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Re: Breakthrough e-bike design. Well, maybe not...

Post by diver » Sep 17 2008 11:08am

I use to have a para plane . i had the chute off and was playing around with it on the road. I just did not realize how fast the prop would push this thing on pavement and went for the ride of my life, no brakes and a pull stick for steering. anyways after the pucker about pinched my hemorrhoids off ,i got it to stop . never again did i try that. this was a plane that flys by parachute and has three wheels with a rotax motor in back pushing a 4 ft three blade prop. I bet it hit over 50 before i new what the heck happened..lol

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Re: Breakthrough e-bike design. Well, maybe not...

Post by etard » Sep 17 2008 1:44pm

Why not just mount the propeller on your head, that way you just go where you look :shock: Haha
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Re: Breakthrough e-bike design. Well, maybe not...

Post by dogman dan » Sep 17 2008 2:14pm

Works best if you mount it straight up on the helmet.

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Re: Breakthrough e-bike design. Well, maybe not...

Post by Link » Sep 17 2008 4:23pm

dogman wrote:Works best if you mount it straight up on the helmet.
Image
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Re: Breakthrough e-bike design. Well, maybe not...

Post by snowcrow » Sep 18 2008 4:52am

EVTodd wrote:I just noticed this quote too: "you cant get in trouble riding it around on the road in my neighbor so id call it street legal". Too funny.
LOL....The only reason no one has flagged him down on the "street legal" thing, is out of fear of losing an appendage :shock:

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Re: Breakthrough e-bike design. Well, maybe not...

Post by rbelisle1 » Sep 18 2008 4:12pm


swbluto   100 GW

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Re: Breakthrough e-bike design. Well, maybe not...

Post by swbluto » Sep 18 2008 7:34pm

I just calculated the expected efficiency for a reasonably ideal high-quality system to be about 46-66% with 56% expected as average, not including battery losses. Compared to a direct-drive's efficiency of 70-80% with a peak efficiency achievable in the 80-85% range, it's clear that an RC motor(such as that one used to here) is more efficiently used as a direct-drive system, assuming adequate cooling and a reasonably ideal gearing. But the nearly constant force that'd provide all over the speed range *would* be nice, but it'd be more powerful as a direct-drive.

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