How do I pick a motor which ask for a certain wattage

[rcKeith]

Hi

 

I've been flying electric for a couple of years now, but still find picking a motor for a plane a struggle. Let me explain.

 

If a ARTF or a kit says you need a 300 Watt motor do I pick a suitable kV and then just divide 300 by 12 (3 cell lipo) to get the current and see which motor is the best match. I know you use the watt per pound rule to work out how may watts you need but how do I pick a motor to match that.

 

Thanks for any advice

 

Keith

[Steve W-O]

The kv will depend on what prop you want to use, that will depend on how you want to fly ie 3D or long duration, what clearance there is for the prop etc.

 

For a 3 cell lipo it is common to use 10V for the voltage for calculations.

 

Current ratings given on motors are often the max permissable, sometimes they give the continuous rating, sometimes both, so better to choose the motor by the rated wattage, and then from that range of motors, the kv to suit your needs. The rating for a motor often include suggested prop sizes

 

A motor of 300W will weigh round about 100g

 

 

Very broad, and I'm sure there will be some better answers

Edited By Steve W-O on 21/03/2011 08:39:02

[Tim Mackey]

Cant say fairer than that Steve

 

RCK - have you checked the various threads and articles we have on here ( and in previous mags ) for help? Like maybe this

Or maybe these threads will help. If not, please ask away and we will do our best to demystify it further.

[rcKeith]

Thanks guys.

 

I get it now, I was sort of there,its filled in the gey areas. Real good info

 

Keith

[Tim Mackey]