PDA

View Full Version : Direct drive heli motors


aramsdell
04-10-2010, 03:17 PM
A couple of years ago I was following a couple threads for direct-drive heli motors for large helis. I think I saw an ad for a small heli with DD recently. Is anyone still working on this for E-Helis?

Twmaster
04-10-2010, 08:08 PM
What do you mean by 'direct drive'? The rotor shaft is direct to the motor?

aramsdell
04-11-2010, 12:47 AM
The maine shaft is more or less the motor shaft too. I've seen some large diameter motors, in Europe I think, and they wre looking promising. They need to be very low kv to get the power from a high voltage pack and thus keep the esc amps down.

kenchiroalpha
04-11-2010, 01:20 AM
Hi
There out of stock at the moment but the Xtreme dd tail rotor works very well
http://www.xtremecx2.com/servlet/the-233/Xtreme-Direct-Drive-Tail/Detail
Take care
Hank

aramsdell
04-11-2010, 03:35 AM
I was thinking something more like this. http://www.rcgroups.com/forums/showthread.php?t=587208

Larry3215
04-11-2010, 03:56 AM
They are pretty rare motors as far as I know. The kV needs to be extremely low for larger helis

On my 50 sized Raptor e-550 for example, Im running 10S into a motor with a kV of 750 but the gearing it about 11 to one. So a direct drive motor would need a kV of about 68 and be able to handle 2000+ watt peaks and about 750 watts continous AND only weigh about 10 ounces.

Thats a pretty tall order :)

On my Dragonus Im running a 3300 kV motor with gearing of about 15/1 so it would need a direct drive motor with a kV of 220 or so that could handle 300 watts or so. Thats a kV way below what a normal outrunner would have.

Those are some very interesting motors for sure.

kenchiroalpha
04-11-2010, 03:56 AM
Hi
Ahh
Heres some good reading if your into DIY motors
http://www.flyelectric.ukgateway.net/motors.htm
And kits
http://www.gobrushless.com/shop/
Take care
Hank

cyclops2
04-29-2010, 12:10 AM
Only KVs & or gears.
People understand gear ratios quickly.
Not so quick on how to generate the same torque in the motor only.

If the rotor speed is a little off. Gears are much cheaper & quicker to adjust.

Look how many years it took to go from expensive inrunners to efficient outrunners.

Maybe the Heli guys will get a break from some motor maker. Some day

groundrushesup
04-29-2010, 12:16 AM
Wasn't the foamy heli offering from Multiplex supposed to be more or less a direct-drive setup with a big-honkin' Low KV outrunner?

Edit: yep, it is.

http://www.multiplexusa.com/new-products/funcopter.html

Larry3215
04-29-2010, 01:50 AM
Only KVs & or gears.
People understand gear ratios quickly.
Not so quick on how to generate the same torque in the motor only.

If the rotor speed is a little off. Gears are much cheaper & quicker to adjust.

Look how many years it took to go from expensive inrunners to efficient outrunners.

Maybe the Heli guys will get a break from some motor maker. Some day

Well, as far as I know we are still working on that one. Only the most expensive outrunners even come close to the efficiency of even average inrunners.

Only outrunners like the Pletenberg and the very few others in that quality class even come close to the efficiency of most inrunners. Even the Plety's dont beet similarly priced inrunners for efficiency.

Cheaper is true for outrunners, more efficient is not true pretty much across the board.

It seems to be the nature of the beast. Outrunners are easier and cheaper to build, but the design has built in limitations that just make it less efficient than an inrunner built to the same or even a lower quality level.

Unless of course you actually believe guys like Little Screamers or the reviews at Hobby City :)