In recent years, brushless DC motors and controllers have begun an unparalleled triumph in model construction and in all technical fields. This book is intended to show how a brushless motor works. The basic principle is discussed first, before all the key terms such as kV and rpm/V, operating voltage, load and idle current, torque, turns, electrical and mechanical power, losses, efficiency, etc. are explained. A brushless motor can't work without a brushless controller, it requires a three-phase AC voltage. To increase the speed properly, the controller must have information on the rotor position. This can be done by Hall sensors or directly via the motor