I have an electric motor for my model planes that has extremely powerful magnets and a dozen or so coils.

 

It is call an outrunner. No brushes. Coils are stationary. The magnets are in the outer shell which rotates.

 

Ball bearings. Very well made. three wires out in a "Y" winding pattern. Just 3 diodes makes it an alternator

with a DC output. Weight is under one pound. Can take up to 40 amps as a motor. Unknown as an alternator. Flies a 6 pound model.

 

 

They come in many sizes and capacities. A motor controller is used to generate a moving flux field to make it a motor.

 

These are very high efficiency motors and were designed for disc drive in computers. They are electrically quiet and are brushless.   

 

Could make a very compact RAT. Ram Air Turbine emergency power source. Maybe enough for ignition anyway.

 

Available in hundreds of sizes down to pencil eraser size.

 

Just a thought.

 

Lynn E. Hanover