Brushless Skateboard Project, help needed!

[Flyin_kiwi]

A mate of mine has been building up a brushless powered skateboard using RC electronics. He's got a whopping 1 KW motor (450ish KV I think) and an 80 amp plane controller driving a toothed belt to one of the rear wheels (Its geared down 2.5 to 1 I think). At the moment he's using his radio to drive it.

The problem: The board runs fine with no load on it, once you stand on it, it jiters like it is triggering overload protection on start up. If you push off and start it rolling then it can accelerate no problems. Any ideas on what to do to fix this? I'll have to get the actual hardwear specs off him. I suspect it may need a proper controller, any ideas on where a guy is to get one? I've done a bit of searching online and haven't found too much. Any help would be much appreciated.

Thanks!

[Ron W3FJW]

He's going to need a centrifugal clutch so the motor can start up and start developing torque to get him going. Motor KV may be too high for that use.

[jeffs555]

Ron is right you need a clutch. Most brushless motors used for RC are sensorless and will have problems starting under load. If you wanted to do it without a clutch you would need a sensored motor and controller.

[Ron van Sommeren]

And/or a sensored controller.

Power systems subforum
http://www.rcgroups.com/power-systems-13/

Search for 'scooter' or 'board'
http://endless-sphere.com/forums/index.php

http://www.vimeo.com/2833402

Prettig weekend ;) Ron

[GreenAce92]

man! those pylon planes are like rocks! without an engine they fall out of the sky lol

[Flyin_kiwi]

Interesting, I though brushless DC gave high torque from start up, so good to know that isn't exactly the case. Now that I think about it, the washing machine DC brushless motors developed at work are for high torque at low speed (Agitation) and are sensored. Might have to look into that, Thanks!

I'm giving him a hand at the moment build a lower KV motor for it using a 52mm dia 14mm thick stator and winding with 0.8mm copper from the afore mentioned washer motors. From what I have read on here I was thinking of winding it DLRK, is that the best way to go for this kind of use?

That is an awesome video of those high speed planes!! Some very good piloting, and camera work too, not the easiest thing to keep in shot. Any idea of the speed?

Thanks,
FK

[GreenAce92]

probably 180 or so that seems to be the average speed that i see all the time when i watch videos of pylon planes

[Ron van Sommeren]

That video should not be in that post. Anyway, the electric racers are now well beyond 400km/h.

@FK
Torque is not the problem here, it's the controller trying to figure out rotor position at startup.

[GreenAce92]

i was talking mph

[Flyin_kiwi]

Ah ok, so they do supply the torque if they can sense the bell position. On discussing it the other day we have a couple of ideas for clutches, but I'm still looking for advice on building the new motor, any ideas?

Thanks for the help, its much appreciated.
FK

[POWERGROOVES]

put a motor

63 inches of pur wipe out

PIG