Check out the Peck Polymers website. Lots of free-flight models and accessories. All I know about electricity is it powers my equipment to get my slobbering, hydrocarbon consuming models to respond. Can't help with using it to spin a prop. I started with "rubber motor" free-flight and I heartily encourage you and your son to enjoy the fun of free flight.

http://www.peck-polymers.com/ [Click on the "online catalog" from the intro site]

PS - the Hind is one of the best looking airplanes (IMHO) that ever took to the skies. Good luck.