Electrics require a different way of thinking. First thing is to get the notion out of your head that "motor == engine." Next is to stop fretting about motor choice. Choosing the motor is the next-to-last step in the process of powering an electric airplane, not the first.

The main thing to remember is that the motor is not where the power comes from. It's where the power goes to. The power really comes from the battery, and that's where you have to start when powering an electric airplane.

It's also okay to plagiarize. Imitation is the sincerest form of flattery. The nice part about this method is you can fly now, and learn about electrics with something that you can hold in your hands, that actually WORKS. Just pick a recommended setup, or one you see in our 3D Electrics forum.

The motor numbers are just designations, like model names for cars and trucks. Technically, they describe one or more dimensions of the motor, but they're useless for determining whether or not a motor is suitable for a particular plane. Just like you have to look at a car's specifications to see if it's something that will work for you, you have to look at a motor's specifications, particularly its maximum ratings for cell count and current. That takes us back to the battery.

It's all about cell count (Volts) and current (Amps) combining to make Watts. Watts is a measure of power, and every plane needs power. The higher the desired performance level, the more power the plane will need. Depending on how we want the plane to perform, we plan on a certain number of Watts per pound of airplane weight. There is a complete set of rules of thumb for Watts per pound, but the two that most pilots will be concerned with these days are:

1. 125 Watts per pound (or more) for 3D
2. 100 Watts per pound for glow-like sport plane performance (i.e. overpowered R-R-R! )

Hope this helps a little.