Nimh batteries are NOT the way to go. I have recently turned my back on them when they required constant peaking for max output. They are heavy, loose charge very fast, and must be cycled around every 20 days or so. Lipos is what I use now for my r/c cars/boat/planes/helis. As dt mentioned, with lipo you hold the plane in your hand and give it not even 100% full throttle and just release it. A 6 cell 3800mah NIMH pack weighs a pound, a 7.2V 5000mah lipo pack weighs half of that, holds its voltage longer and allows for larger current draws. However, lipos are dangerous if not taken care of. They do blow up and they do set people's cars/houses on fire if not kept in safe spots. They only do that if cells are unbalanced, or have been damaged but the damage went unnoticed. They are also very expensive
. Your idea is a great one, as a matter of fact about 2 weeks ago I started thinking of the same thing, but instead converting something like a hatchback. I looked into it and it seems that a DC motor is more optimal than AC. A brushless motor of that size would be more expensive than brushed, and probably hard to find. DC brushed are sold at websites like this one
http://www.electroauto.com/
I'm experimenting with hydrogen right now
Vova