Gyros are critical to the stabilisation of Radio Controlled Helicopters, and can also be utilised in Radio Controlled Aircraft. A gyroscope or gyro for short is a high precision electronic device. Using piezo technology the gyro senses the direction of flight of the model aircraft, and makes subtle adjustments to the rudder Servo if it recognises any deviation from it's course. In helicopters the gyro will automatically apply extra rudder to the model when the head rotation speed increases, which creates counter-torque in the body. If rudder or aileron is applied by the operator, this overrides the function of the gyro until that control is released, then the device will recalibrate itself to the new heading. For complicated stunt flying, or competition flying a heading hold or heading lock gyro is a must, giving far greater levels of stability in this fast moving environment