Comments on: Mission One Now a Full Fairing Electric Racer http://thekneeslider.com/archives/2009/05/26/mission-one-now-a-full-fairing-electric-racer/ Motorcycle News for Positive People Sun, 12 Feb 2012 09:09:53 +0000 hourly 1 http://wordpress.org/?v=3.3.1 By: Miles http://thekneeslider.com/archives/2009/05/26/mission-one-now-a-full-fairing-electric-racer/#comment-242278 Miles Fri, 29 May 2009 00:06:04 +0000 http://thekneeslider.com/?p=5991#comment-242278 @ pabs "wow that pretty clever took me a minute to figure out what you meant, i understand how each motor would be geared to provide optimum performance for lower or higher speed but i’m unclear how such an arrangement would provide gearing " As it was explained to me (in my Automotive Transmissions class in college) the second motor can travel forwards or backwards at 20 RPM, thus changing the gear ratios by a similar amount. I don't know how accurate that explanation is, but you can probably mock up one with some Lego Technics, or any differential you want to use (maybe a riding lawnmower, or a car up on jackstands with the driveshaft disconnected). " . . . also you’d be trading the weight of a gearbox for that of a motor one motor could also be on the outside of the ring so the two motors counter rotate to each other" Well, each motor could weigh half (and generate half), maybe a tiny bit more to make up for the frictional losses. Interesting info, this is the "transmission" the Prius uses: http://www.cleangreencar.co.nz/page/prius-transmission http://blog.autospeed.com/2009/01/22/new-diy-electric-car-opportunities/ @ pabs
“wow that pretty clever took me a minute to figure out what you meant, i understand how each motor would be geared to provide optimum performance for lower or higher speed but i’m unclear how such an arrangement would provide gearing ”

As it was explained to me (in my Automotive Transmissions class in college) the second motor can travel forwards or backwards at 20 RPM, thus changing the gear ratios by a similar amount. I don’t know how accurate that explanation is, but you can probably mock up one with some Lego Technics, or any differential you want to use (maybe a riding lawnmower, or a car up on jackstands with the driveshaft disconnected).

” . . . also you’d be trading the weight of a gearbox for that of a motor
one motor could also be on the outside of the ring so the two motors counter rotate to each other”

Well, each motor could weigh half (and generate half), maybe a tiny bit more to make up for the frictional losses.

Interesting info, this is the “transmission” the Prius uses:
http://www.cleangreencar.co.nz/page/prius-transmission

http://blog.autospeed.com/2009/01/22/new-diy-electric-car-opportunities/

]]> By: ROHORN http://thekneeslider.com/archives/2009/05/26/mission-one-now-a-full-fairing-electric-racer/#comment-242172 ROHORN Thu, 28 May 2009 03:28:52 +0000 http://thekneeslider.com/?p=5991#comment-242172 It needs a transmission about as badly as it needs a kickstarter. It needs a transmission about as badly as it needs a kickstarter.

]]> By: pabs http://thekneeslider.com/archives/2009/05/26/mission-one-now-a-full-fairing-electric-racer/#comment-242111 pabs Wed, 27 May 2009 21:29:55 +0000 http://thekneeslider.com/?p=5991#comment-242111 miles wow that pretty clever took me a minute to figure out what you meant, i understand how each motor would be geared to provide optimum performance for lower or higher speed but i'm unclear how such an arrangement would provide gearing also you'd be trading the weight of a gearbox for that of a motor one motor could also be on the outside of the ring so the two motors counter rotate to each other miles
wow that pretty clever took me a minute to figure out what you meant, i understand how each motor would be geared to provide optimum performance for lower or higher speed but i’m unclear how such an arrangement would provide gearing also you’d be trading the weight of a gearbox for that of a motor
one motor could also be on the outside of the ring so the two motors counter rotate to each other

]]> By: Miles http://thekneeslider.com/archives/2009/05/26/mission-one-now-a-full-fairing-electric-racer/#comment-242061 Miles Wed, 27 May 2009 17:52:27 +0000 http://thekneeslider.com/?p=5991#comment-242061 @ Highspeedhamish Color me dumb, but why isnt there a frikken transmission on these things? Surely the lower the rpm the less drain on the batteries. Its not like your going to full throttle it in a corner and risk a hide side. Electric motors have one moving part, and AC motors have one friction part, sealed bearings. I think they can easily spin faster than a standard internal combustion engine. IF you wanted a transmission, might I suggest a dual motor powered planetary gearset? Simply have two electric motors on a planetary system, by varying the speed and direction of the motors you can generate infinite "gear ratios", and probably a thousand pound feet of torque. An important consideration is where the opposing force is coming from? The batteries and rider, that is finite. It is best to take that into account when designing the torque used for acceleration. BTW, I think the motors used can generate 300-400lbs of torque quite easily and reach over 15,000RPM, so no need for gear ratios. Another thing to think of is the wind resistance, there is no need for the bike to go over 200mph, and I am sure it can have plenty of acceleration and reach triple digit speeds with only one gear. (Think about the Diesel F1 cars, they went to 5 gears and they don't even have the low end torque of electric motors, and I am guessing they don't have the RPM capability either.) @ Highspeedhamish
Color me dumb, but why isnt there a frikken transmission on these things? Surely the lower the rpm the less drain on the batteries. Its not like your going to full throttle it in a corner and risk a hide side.

Electric motors have one moving part, and AC motors have one friction part, sealed bearings. I think they can easily spin faster than a standard internal combustion engine.

IF you wanted a transmission, might I suggest a dual motor powered planetary gearset? Simply have two electric motors on a planetary system, by varying the speed and direction of the motors you can generate infinite “gear ratios”, and probably a thousand pound feet of torque.

An important consideration is where the opposing force is coming from? The batteries and rider, that is finite. It is best to take that into account when designing the torque used for acceleration.

BTW, I think the motors used can generate 300-400lbs of torque quite easily and reach over 15,000RPM, so no need for gear ratios.

Another thing to think of is the wind resistance, there is no need for the bike to go over 200mph, and I am sure it can have plenty of acceleration and reach triple digit speeds with only one gear. (Think about the Diesel F1 cars, they went to 5 gears and they don’t even have the low end torque of electric motors, and I am guessing they don’t have the RPM capability either.)

]]> By: JC http://thekneeslider.com/archives/2009/05/26/mission-one-now-a-full-fairing-electric-racer/#comment-242002 JC Wed, 27 May 2009 13:22:07 +0000 http://thekneeslider.com/?p=5991#comment-242002 The torque curve of the motor changes drastically depending on if you are talking an AC motor or a DC motor. The DC motor has huge torque at zero and low rpm, and then the torque falls off as rpm increases. This results in little passing acceleration, and makes for a lower high speed relative to the motors peak power potential. It would benefit from a transmission, even if it was just a two speed. FWIW, Killacycle (dual DC motors) uses the motor controller to switch between the motors in parallel and the motors in series, essentially creating a two speed transmission electrically. The Tesla roadster uses an AC motor, and even it initially tried to develop a two speed transmission, and gave up due to reliability and cost and went with a single gear reduction and in part made up for it by modifying the motor controller. They lost little of the top speed and changed the 0-60 by not that much by losing the second gear. Most car EV conversions use the existing gearbox, even if they only use one or two of the gears. Unfortunately a motorcycle with it's (in most cases) integrated motor/gearbox isn't as easy to add a transmission, and it becomes a relatively large expense and weight when all you really wanted was a second gear and not 5 or 6. Ok, rambling aside, it makes it obvious the solution is AC motors in motorcycles, and these have not caught on very quickly in the EV conversion world due to higher cost. The torque curve of the motor changes drastically depending on if you are talking an AC motor or a DC motor.

The DC motor has huge torque at zero and low rpm, and then the torque falls off as rpm increases. This results in little passing acceleration, and makes for a lower high speed relative to the motors peak power potential. It would benefit from a transmission, even if it was just a two speed.

FWIW, Killacycle (dual DC motors) uses the motor controller to switch between the motors in parallel and the motors in series, essentially creating a two speed transmission electrically.

The Tesla roadster uses an AC motor, and even it initially tried to develop a two speed transmission, and gave up due to reliability and cost and went with a single gear reduction and in part made up for it by modifying the motor controller. They lost little of the top speed and changed the 0-60 by not that much by losing the second gear.

Most car EV conversions use the existing gearbox, even if they only use one or two of the gears.

Unfortunately a motorcycle with it’s (in most cases) integrated motor/gearbox isn’t as easy to add a transmission, and it becomes a relatively large expense and weight when all you really wanted was a second gear and not 5 or 6.

Ok, rambling aside, it makes it obvious the solution is AC motors in motorcycles, and these have not caught on very quickly in the EV conversion world due to higher cost.

]]>