LightningRods mid drive kit

[LightningRods]

I don't want to put the motor on the boom regardless. Because of the Rotovelo's molded body the area behind the seat is outside of the body shell. I want to mount the motor and batteries outside of the body behind the seat. That way you don't have any noise from the motor and drivetrain inside of an echo chamber with you. Plus by adding a jackshaft behind the seat I can shorten the pedal chainline and have two stage gearing for higher gearing without using huge sprockets. Finally, having the motor and batteries low and centrally mounted is going to make the tadpole handle better. I really do want to build one. I'd like to see if I could get 1,000 mpg(e) at 50 mph.

 

[waynebergman]

LR I am around 130 lbs these days. Just about as skinny as you can get. I would be glad to pilot it for you for your record setting efforts.

 

[LightningRods]

You have the right physique. How would you feel about doing 100 mph in a plastic banana? :lol:

If we could hit 'the ton' I'd love to show that a rig like this can get over 100 mpg at over 100 mph. All performance is about efficiency.

 

[waynebergman]

Looks like I am all just talk now. I am getting pretty old now, but I did not plan on bringing my diapers for this one. Maybe keep me on your back up list.

 

[LightningRods]

I don't know that the Rotovelo would do 100 mph with 4 kW. The factory spec is for 40 mph @ 300 watts. It seems likely to me that more than 13x the power required to do 40 would send a very aerodynamically efficient shape 2.4x as fast. Another question would be how stable (or unstable) it would be at that speed.

 

[turbo1889]

In my experience the speed to power relationship is a square root relationship. Or in other words twice the speed is possible with four times the power input, three times the speed is possible with nine times the power input, four times the speed is possible with sixteen times the power input.

Speed = (Vehicle Specific Constant) x SQRT(Mechanical Power Output)

All that assuming you have the necessary gearing range and the vehicle is capable of traveling that fast without structural failure and or not being controllable and crashing.




So if the suggested "Yellow Banana Mobile on Electric Steroids" is rated for 40-mph at 300-watts mechanical input power then theoretically for that vehicle:

Speed(mph) = 2.3094 x SQRT(mechwatts)



Sounds like you should be able to easily hit 100-mph if power is the only limiting factor.

 

[LightningRods]

Sounds like you should be able to easily hit 100-mph if power is the only limiting factor.

I agree. I'm overkill on power. Stability and control will be the issue. I also worry about the tires. A blowout at 90 would suck. So much.

How fast is 100 going to look with your butt just a few inches off the road and your eyeballs not much higher?

 

[turbo1889]

Since the pod is open to the ground below the pedals also be sure to use clip in pedals and/or consider closing up those openings. Having a foot come off a pedal or in any way make contact with the ground underneath at 100-mph could be disastrous.

As to tires, I would think some of the heavier duty puncture resistant multiple layer Kevlar reinforced tires would probably do the trick with a little lower then normal air pressure to start so that the heat doesn't increase the pressure over the limit

Still there are a lot of little things that could go wrong at that speed and cause big problems.



If I remember correctly though the world record for fastest human powered cycle speed for a short sprint is like slightly over 80-mph and they used one of those fiberglass pods (only absolutely fully enclosed not even the head sticking out but rather clear sections of the aero-pod to see through) with a really athletic person who could really punch out some power for a short period. So its not like no one has ever tried to go really fast in one of those things before and managed to pull it off.

I think it can be done, and I hope you succeed.

Something possibly more useful though might be to scale down to a maximum speed of about 70-mph or so and use up some of the power to propel more drag inducing but still minimal weight and width motorcycle wheels and tires that are designed for those speeds with a little wider stance on a little heavier of a frame for better stability and strength but still with the light weight aero-pod body. Fast enough to run on the highway and hold pace with cars and with components that can handle those speed levels as a regular thing without problems. Which if it were me doing that I'd make the nose clear and the battery and motor area not clear so people could see I was pedaling but not see the motor. Would just love the look on the faces of people driving cars as a result.

 

[Warren]

Cedric Lynch said he regularly sees 25-26 Wh/mi on his CA at 50 mph. He ran 14 and more recently 18, 100 Ah Thunderskys to his Agni, so it isn't light. But he does have a bungee suspension with about 1.5 inches of travel.

I believe he runs Schwalbe e-bike tires.

http://www.bikeweb.com/node/693

http://www.schwalbetires.com/bike_tires/e-bikes

An enclosed trike will have higher rolling and aero drag, but I'd guess no more than .3-.5 times higher, so 32.5-39.0 Wh/mile at 50 mph.

 

[LightningRods]

Certainly a much more useful exercise would be to show that the velomobile can reach and maintain normal legal freeway speeds and then record the incredibly small amount of energy required. Trying to go 100 mph is just showing off, plain and simple.

Not that I am above such things.

 

[emaayan]

the banana-rod looks suspiciously like your dream machine... i'm gonna stop now before the PTB's would spank me here again.

 

[turbo1889]

Certainly a much more useful exercise would be to show that the velomobile can reach and maintain normal legal freeway speeds and then record the incredibly small amount of energy required. Trying to go 100 mph is just showing off, plain and simple.

Not that I am above such things.

Nor should you be !!! If you got it, flaunt it !!! (So long as excessive speed isn't endangering any other innocent bystanders of course.)

Same sort of show off mentality in my idea of making the nose of the pod clear so that everyone could see the rider pedaling going down to the road at 70-mph without seeing the motor. Major show off quotient in that idea.

 

[emaayan]

you try and integrate it with a torque sensor ,so it would half -right sort of..

 

[SolarRay]

What iron loss in a small block at high speed?
2000..3000..4000..5000..6000..7000..8000rpm
Anyone conducted these measurements?

 

[recumpence]

Bear in mind, that kind of speed is really difficult. The fairing makes an enormous difference. But, you will find it will take far more power to hit 100 mph than you may think on the surface.

Normal though is 4 times the power gives twice the speed. However, in practice there are far too many variables to consider. My experience is that it is closer to 6 times the power required for a doubling of speed. But, a fairing is something I have not used.

Anyway, bicycle drive components become very sketchy with the kind of power required for such a speed run.

If you truly want to shoot for 100, I would say run a BMX chain to the left side of the wheel. It can handle much more power that way.

Matt

 

[LightningRods]

Hi Matt! Thanks for checking in. I was wondering if this project would interest you.

I'm really not concerned about having enough power. I don't think it would take anywhere near the amount of power that one of your DaVinci Astro drives put out. What I am concerned about is staying under control at that speed. I've had high speed wobbles on bicycles at around 50 and motorcycles at about 120. Those definitely count among the most terrifying experiences that I've had. IF I get the Rotovelo as I want to I'll no doubt take it real easy and sneak up to 50, 60, 70 and then see if I have the clankers to go any faster.

For the purpose of hitting a top speed on flat ground you're absolutely right. Hill climbing and low speed acceleration aren't an issue. Single run would probably be the best bet just to keep things as strong and simple as possible. Less to go wrong is good here.

I loved your crazy fast yellow recumbent. No doubt what got me thinking along these lines. Your twin Astro drive in a fully faired velomobile would need to go to Bonneville.

 

[Marc S.]

An enclosed trike will have higher rolling and aero drag, but I'd guess no more than .3-.5 times higher, so 32.5-39.0 Wh/mile at 50 mph.

A velomobile like the Rotovelo will have slightly higher rolling resistance (cr 0.0075 for two, compared to cr 0.0096 for three touring tyres) but vastly lower aero drag. Aero drag will be about 1/3 or less compared to a mountain bike. The Ebike Simulator predicts just under 20Wh/mile at 50mph.

Check for yourself: http://www.hembrow.eu/personal/kreuzotter/espeed.htm

 

[Marc S.]

I really like the idea to implant your drive into a velomobile! Thats exactly what I like to do when I get one. (that will take some more saving, though)

But, why did you choose an unsuspended Trislet Rotovelo for this kind of speed?
Because of its rugged shell?

My choice would be one of the more refined and efficient models, like the WAW (front suspension, 26" rear wheel, detachable front and rear body parts, about 25-28kg) http://www.katanga.eu/gallery

I haven't had the chance to ride one yet, but the WAW is well regarded in its high speed corner handling.
Here is a look at the rear wheel without the tail body part. There might be enough space to bolt your drive unit to the rear bulk head.

Anyway, before getting the Rotovelo, check-in at the very friendly velomobile forum for some tips: http://www.bentrideronline.com/messageboard/forumdisplay.php?f=15

 

[emaayan]

http://www.electricbike.com/motor-tech-learn-the-terms-part-1/

"and the best high-powered mid drive is about to become available to the public this month…the Lightning Rods kit (look for our review next month)".

hmm, no pressure...

 

[LightningRods]

A velomobile like the Rotovelo will have slightly higher rolling resistance (cr 0.0075 for two, compared to cr 0.0096 for three touring tyres) but vastly lower aero drag. Aero drag will be about 1/3 or less compared to a mountain bike. The Ebike Simulator predicts just under 20Wh/mile at 50mph.

Pretty respectable. I calculate a 38 mile range from my present very modest 48V 16 ah battery pack. There's plenty of room under the body to at least double that capacity. 76 miles is getting into Nissan Leaf territory. Your butt would give out before the battery did.

At 20Wh/mile I come up with 1,685 mpg(e)! Do we really love the oil producing countries and Big Oil that much?

 

[emaayan]

A velomobile like the Rotovelo will have slightly higher rolling resistance (cr 0.0075 for two, compared to cr 0.0096 for three touring tyres) but vastly lower aero drag. Aero drag will be about 1/3 or less compared to a mountain bike. The Ebike Simulator predicts just under 20Wh/mile at 50mph.

Pretty respectable. I calculate a 38 mile range from my present very modest 48V 16 ah battery pack. There's plenty of room under the body to at least double that capacity. 76 miles is getting into Nissan Leaf territory. Your butt would give out before the battery did.

At 20Wh/mile I come up with 1,685 mpg(e)! Do we really love the oil producing countries and Big Oil that much?

hmmm, that would be like 83 km on my triangle battery , on 60 kph? oh the torture of waiting..

 

[LightningRods]

I really like the idea to implant your drive into a velomobile! Thats exactly what I like to do when I get one. (that will take some more saving, though)

But, why did you choose an unsuspended Trislet Rotovelo for this kind of speed?
Because of its rugged shell?

I've already been working with a couple of customers in Holland who have velomobiles. They are just using my current kit on the boom. I feel strongly that a mid bike motor location with a jackshaft would be hugely superior. Whether I get my own velo or not (mostly a matter of money) I will be developing electric drives for them.

Yes the reason I like the Rotovelo is the impact resistant 'Frisbee' plastic shell. I hate worrying about body work. After fuel costs and insurance, dealing with body damage is one of the most annoying and constant expenses of owning an automobile.

Thank you for the link to the velomobile forum. I'll do some lurking and see what I can learn.

 

[LightningRods]

http://www.electricbike.com/motor-tech-learn-the-terms-part-1/

"and the best high-powered mid drive is about to become available to the public this month…the Lightning Rods kit (look for our review next month)".

hmm, no pressure...

Sweat, sweat, sweat. It's pressure like this that makes me continue to revise and fiddle with the kit rather than just jump into production. At this point there is nothing for me to do but put them out there. I AM NOT PERFECT AND NOTHING I MAKE IS PERFECT! I do the best that I can and plan to continually improve my work based on feedback from customers.

I'm glad that I did limited releases on a lot of my more experimental parts. I've been able to make huge improvements in performance and reliability. WIth a bit of luck I may even come close to living up to my P.R.

 

[emaayan]

http://www.electricbike.com/motor-tech-learn-the-terms-part-1/

"and the best high-powered mid drive is about to become available to the public this month…the Lightning Rods kit (look for our review next month)".

hmm, no pressure...

Sweat, sweat, sweat. It's pressure like this that makes me continue to revise and fiddle with the kit rather than just jump into production. At this point there is nothing for me to do but put them out there. I AM NOT PERFECT AND NOTHING I MAKE IS PERFECT! I do the best that I can and plan to continually improve my work based on feedback from customers.

I'm glad that I did limited releases on a lot of my more experimental parts. I've been able to make huge improvements in performance and reliability. WIth a bit of luck I may even come close to living up to my P.R.

just be careful not to say you'd release it when "it's done" http://en.wikipedia.org/wiki/Duke_Nukem_Forever#Development

 

[LightningRods]

No, I know better. It's never done.