Question: I see the term "Outrunner" in some of the Electric Motor information. What does "Outrunner" mean?

Answer: The following explanation should help you out.

a) A tradionaal "Inrunner" motor is the generally familiar design we have all become used to since electric motors were first invented. The inside of the motor rotates including the drive shaft to which is often attached a gear or pulley of some sort. The outside case of the motor is fixed. The case does not rotate and the case is often incorporates some sort of mounting flange or holes allowing the outside case and the motor itself to be bolted or clamped down to a platform or mounting system. From the outside of this traditional inrunner type of motor, only the shaft appears to rotate.

b) An outrunner motor has the shaft attached to the outside case of the motor and when the shaft rotates the entire outside case of motor rotates along with it. The inside of the motor is fixed and usually attached to a mounting plate of some sort at the back of the motor. This design has been around for many years but in modeling it is relatively new. Outrunner motors are generally brushless high power motors and offer the advantage of usually producing more power and being more efficient (using less energy) than inrunner motors.