They're very light even with all that copper winding. I can get an off the shelf 15Kw (21hp) DC brushless r/c motor that weighs 2 kg. Add the controller to that and you're looking at 3-4 kg, tops. There is no combustion engine that comes close to that, not even a turbine can deliver that kind of power-to-weight ratio.
All one has to do is look at the revolution in the r/c field. The electric aircrafts shatter everything and are not even allowed to compete with the nitro/turbine ones because they cleaned up so much - they had to create an electric class just for them. Now, naturally they don't need to take much notice of endurance, so they can use light battery packs and overpower them, but still.
Electric makes sense. We just need a way to store the energy now. When that's licked, it's game over for the combustion engine.
Last edited by AdamFrisch; 15th Jan 2010 at 14:51.