Andre':

Your last post mentioned 24v at 5A current. This 100W is over the maximum sustained power for a can motor, and your 10K rpm limit suggests that is what you had in mind. Additionally, I don't know of any that operate at 24v, you'd have to go with 12v at 10A current. And that is too much for the brushes in a can motor. A good "Cobalt" brushed motor could easily take 10A through it, but you can also get one would for 24v with no trouble. And it will operate happily all day long at 20K rpm or higher with its ball bearing support of the armature. Staying at a 10K limit will lower the efficiency also. But the self rectification through the commutator and brushes will be the biggest loss. By eliminating the brushes you also eliminate the items of greatest wear.

If you are at all familiar with AC electric motors you know about three phase motors, and their greater efficiency compared to single phase motors. The "Brushless" model motors are three phase units, the ESC converts the DC th 3P ac to run it. Since the model motors use permanent magnets instead of induction in the armature, they can be used as three phase generators, just like the alternator in your car other than the DC feed to the rotor in your car's unit. A similar six-diode bridge will convert the 3P generator output to a really clean DC, rather than the "Notchy" peaked output of a brushed DC generator. Each diode in the rectifier pack will have to be rated for the maximum system current, and probably be mounted on a heat sink as well. Both these will add to the cost, but just a small amount.

You will have to have some form of voltage regulation. The alternator in your car is controlled by varying the power into its rotor, changing the strength of the rotating magnetic field. Using permanent magnets you'll have to use external regulation, independent of the generator.

The only disadvantage, when compared to a 550 or similar "Can" motor is the cost. Compared to a cobalt brushed motor though, there's not that much difference in the cost of the generator set. Either one will need some form of voltage regulation.

Just a thought - If you replace the truck motors with 3P motors as well you could then use a battery set as part of your voltage regulation, and with some radio controlled jiggery-pokery in switching you could operate the "Generator" as an on board starter for the engine, then switch things back and drive the truck motors with the same ESC.

As Bob27 said, you will need a throttle controller for the engine, you could use an ordinary RC servo in parallel with the ESC for the truck motors to throttle the engine up when you call for more power to the trucks.

Hope I've made my thoughts clear.

Bill.