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Luke's new race bike build thread.

Joined
Oct 28, 2008
Messages
14,539
Location
Manhattan Beach, CA, USA
I'm building a new bike for this Willow springs race June 18th.

I ordered $660usd in CroMo tubing in various sizes last night.
My friend Paul ordered some various bending/jigging/clamping tools for frame building and a new welding table.

The motor came today, hand delivered by its creator, who is a VERY awesomely smart guy. Thank you Diederik! (yes, he reads ES sometimes. :) )


The frame will be rigid rear, possibly sprung front, if and only if I can find a fork with an extremely stiff dampening rate, extremely rigid bodies and crown, and just a couple inches of suspension at the most. IMHO, 99.9% of suspension forks on bikes racing a kart track are going to be a big hinderer to riding rather than a help.

Brake will be dirtbike based this time rather than the Hayse stroker ace downhill brakes on 8.5" rotors that I used last time, which faded something awful at the death race, and regularly boil and warp rotors on the pink bike. Brakes are extremely important road racing, having something you know wont fade gives you the confidence to commit to corner entry speeds you wouldn't otherwise try. I would like to get the Brembo setup off a KTM if possible. Might just take the brake setup off one of my KTM's and borrow it for this bike.

So, step one to any build is sourcing and deciding on the pieces that will best work together, and step 2 is making all the custom parts and systems to attach them together and make them play well. I'm exiting phase 1 at this point, and excited to get going on phase 2 this weekend.


So, now I've got to find a decent controller for my motor... So, let's measure the resistance and see what ball-park we're in for controller loading.

jobyresistance.jpg



So, you will notice on that sexy sexy 6.5digit ethernet linked Kethley DMM and the Sorensen 8-125 power supply current set to 50amps, we have a phase winding resistance of ~50mOhm. The motor has a KV of 28. This basically means it won't be straining any controller, but it will need some voltage to get it up to speed, so let's see what we have for controllers in the 120v area.

Hmm... Hmm... so many to choose from! What to pick! What to pick! Since I'm not going to be running more than 10hp (as agreed with the fellow hosting this event), I think I will go with the baby size#2 sevcon, which will be just about right for my modest power needs here.

jobycontroller.jpg



Now we need a ~120v battery... something pretty light and stiff, with plenty of capacity.

Ahh, yes, here we go, didn't even have to get out of my chair to reach a compact little pack that will suit my needs. :)

jobybatt.jpg



So, now it's time for a little CADoodling to design a sprocket adapter for this fantastic motor that was built to mount a prop, and time to begin picking suitable frame geometry.

9days till the race, and so far, I've got some parts selected. :) Should be cake. :)
 
WOW, what is that thing? Also what type of batteries are those?
 
Whiplash said:
WOW, what is that thing? Also what type of batteries are those?


The motor is just a little 1,800gram toy. ;) It was actually made by some VERY sharp guys for use in going up into the sky on a kite with a 3ft chunk of carbon fiber bolted upon its face. (not a joke)

No motor under 4lbs should be worth worrying about. Right? Right? Ok, maybe a tiny bit of worry would be OK. ;)


The batts are just the cheapest hobbyking 20-30C hardpacks they sell. Something like $0.38-watthour I think. This is a low power application though, so they should do fine. :) If my Nano-tech shipment arrives before then, I will switch it up to Nano's if I have time, but likely this pack will just do fine for my modest needs here.
 
That's an interesting motor. Why the magnet pairs like that, I wonder, and are they alternate or same polarity, within the pair?

Since the motor appears to only have a bearing at one end, are you going to stick a pillow bearing on the other end of whatever adapter/shaft you use on it? I ask because if it's designed for a prop, the bearings and such at teh other end probably arent' setup for side-loading so much as axial, right? Kinda like a drill? (which is why I think a lot of the RC motors meant for helis and planes dont' seem to always hold up so well in chain drive stuff without bearing mods)



BTW: those blocked out squares make me more interested in what might be behind them than what is actually in the pics. ;)


EDIT (added): Found an article about the kites/motors:
http://blog.cafefoundation.org/?p=3303
 
Nice project Luke!

Btw.. do you plan on testing it on an dyno :wink: :lol:

Probably... AFTER the race! right :lol:

That motor must have strong glue holding the magnets!.. they are subject to the centrifugal force!

The winding look like a reversed HT motor stator with central rotor...

Do you have any numbers about the efficiency?

Doc
 
amberwolf said:
That's an interesting motor. Why the magnet pairs like that, I wonder, and are they alternate or same polarity, within the pair?

Since the motor appears to only have a bearing at one end, are you going to stick a pillow bearing on the other end of whatever adapter/shaft you use on it? I ask because if it's designed for a prop, the bearings and such at teh other end probably arent' setup for side-loading so much as axial, right? Kinda like a drill? (which is why I think a lot of the RC motors meant for helis and planes dont' seem to always hold up so well in chain drive stuff without bearing mods)



BTW: those blocked out squares make me more interested in what might be behind them than what is actually in the pics. ;)


It has a pair of 50mm ID thin section precision ball bearings in it. This is stronger bearing support than any hubmotor, RC motor, or even an Agni. Also, it only has to last 1 race, and if it breaks, that's OK too, racing is a game of learning and discovery.

The magnets are setup as they are, because it's the best way to do it. ;)

Size wise, every hubmotor will be bigger and wider than this little guy. The RC outrunner motors will be heavier and thicker. Fortunately, when you're >95% efficient with a perfect heatsink setup, you don't need to be very big to party with the big boys. :)
 
Doctorbass said:
Nice project Luke!

Btw.. do you plan on testing it on an dyno :wink: :lol:

Probably... AFTER the race! right :lol:

That motor must have strong glue holding the magnets!.. they are subject to the centrifugal force!

The winding look like a reversed HT motor stator with central rotor...

Do you have any numbers about the efficiency?

Doc


Yep, glue has to be good on inrunner motors. Fortunately, these guys know exactly what they are doing though. :)

Efficiency is >95%, and over a wide range of power levels and RPMs. No, that's not a typo, this is one of the best motor designs on the planet. I bet Miles and a few other folks have ID'd which company the motor is a prototype from. This will be the first time this company has ever had one of their motors power something that doesn't fly way up in the sky. :)
 
Hillhater said:
http://endless-sphere.com/forums/viewtopic.php?f=30&t=27571

http://www.jobymotors.com/public/views/pages/products.php


Yup. :)
 
Rad!

Can't wait to see how the elegant double rotor bearings hold up. What's the max erpm on the G8035? What size wheels?
 
Biff helped me get the hall sensors figured out positionally tonight, and glued into place. It rocks having a friend who is a professional motor engineer, and a bad-ass-super-smart-guy.



The sevcon's do 2,000hz maximum IIRC, so on this motor with 26 pole pairs (I think it was 26?), it should be able to spin her up to ~4,600rpm, which should be fine for my sub 10hp power needs.

Also, this motor doesn't have a datasheet, it's just an early prototype design.
 
Concerning it being an inrunner, once Miles clearly explained the benefits of the outrunner configuration of motor, I understood why it was beneficial for E-bikes because of the limited space on a bike frame. With the magnets being noticeably thinner than the coils, by placing the magnets on the outside of the magnetic interaction, the work is performed farther from the shaft to gain a small improvement in leverage, and torque-per-watt applied.

That makes sense if we are limiting ourselves to a setup similar to PaulD's deathrace bike. A ~72V system where we use a modest 30A on (using affordable off-the-shelf components), we can supply 2100W (3-HP).

Since you don't need long range, you are leaping far past everyone else and going straight to 120V!! At that voltage, it is my opinion that any theoretical 10% torque-per-watt advantage an outrunner of identical diameter might have...is far outweighed by this inrunners ability to shed heat, since the coils are attached to the stationary shell. If active cooling eventually proves to be helpful after severe testing, that would be a piece of cake to install.

I noticed that after PaulDs set-up was advertised, the 80-100 was suddenly out-of-stock. Like most of history, it appears that your opponents are tooling up to fight the last battle,...instead of the next one!
 
spinningmagnets said:
. Like most of history, it appears that your opponents are tooling up to fight the last battle,...instead of the next one!


I always gear-up assuming my opponents have doubled what they had the last time we met. :)

Then I like to push things hard enough during the race that it becomes the last race that machine ever does. lol

But in this case, I really have fallen in love with the motor and don't want to hurt it, and I agreed not to exceed 10hp, so all the parts are going to have a pretty cush life on this build.
 
lol, that motor looks like a work of art :) Cant wait to see the video footage of the race... hope you are going to strap a camera to the BACK of that thing so we can see how fast you smoke the competition. :evil:
 
Luke you're a lucky lucky man. Or well-connected, or both. You'll do that motor proud no doubt. Good skills.
 
Looking Good so far Luke,
In a word, Jealous!
I don't have access to all that cutting edge goodies.
Any ways, looking foward to seeing how it all comes together. Good also to see you with such an early start on the project. :wink:
 
You have sure been in eVehicle heaven since moving to CA. All the best with this build. Everything moving up a notch ... a big notch! :D
 
This is fun stuff to follow, I look forward to the race. I want one of those motors on a powered parachute. It would be as fun as Kiteboarding. Be sure to get videos of the race, it sounds like electrics are going to dominate once again.
 
Try www.actiontec.us for your suspension fork. Very cool in-head tube design and he can build it custom with different damping, spring rate, and travel. It requires a 1 1/4" head tube, but since you are building your own bike that should not be an issue. After all you have 9 days!

I used one of these on my streamliner and it worked great to make the bike stick like glue on the bumpy corners. I agree, for a track race only front suspension is desired.

-Warren.
 
nicobie said:
It appears that etard/thud might have a problem. :mrgreen:


Come on guys, you gonna let him talk about you like that?? LOL!
 
I love it. Its great seeing you build shit like this luke! And I like how its "not over 10hp" lol 10hp output at the motor at 2626 rpm is 20 ft/lbs or.... 10hp at the motor output at 525 rpm is 100 ft/lbs output!!!! Then you multiply the total torque of the motor by the reduction of your gearing for the rear wheel torque! So it all depends on the motor efficiency at the given rpm :wink:

In conclusion if you dont blow up you will win!
Good luck buddy!
 
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