Flight controls allow pilots to control the collective and throttle (usually linked together), the cyclic controls (pitch and roll), and the tail rotor (yaw). Controlling these in unison enables the helicopter to perform most of the same maneuvres as full-sized helicopters, such as hovering and backwards flight, and many that full-sized helicopters cannot.
The various helicopter controls are effected by means of small servo motors, commonly known as servos. A piezoelectric gyroscope is typically used on the tail rotor (yaw) control to counter wind- and torque-reaction-induced tail movement. This "gyro" does not itself apply a mechanical force, but electronically adjusts the control signal to the tail rotor servo.
The engines typically used to be methanol-powered two-stroke motors, but electric brushless motors combined with a high-performance lithium polymer battery are now more common and provide improved efficiency, performance and lifespan compared to brushed motors, while decreasing prices bring them within reach of hobbyists. Gasoline and jet turbine engines are also used.