gust (wind). A temporary increase in the speed of the wind. A gust lasts for a very short period of time, and it is usually followed by a wind whose speed is lower than normal.
gust lock (aircraft control systems). A ground lock for aircraft controls, used to prevent the wind damaging the control surfaces by knocking them against their stops. Gust locks may either be built-in features of the control system or external locks that are slipped between the movable surface and the fixed structure.
All gust locks are required to have some kind of warning device to indicate to the pilot that they are installed or engaged.
gyro. See gyroscope.
gyrocompass. A form of navigation instrument that uses a gyroscope as a stable reference for a direction-seeking pickup. The direction-seeking pickup of a gyrocompass lines up with the magnetic field of the earth just as an ordinary magnetic compass, but the gyroscope keeps it from oscillating.
gyrodyne. 14 CFR Part 1: “A rotorcraft whose rotors are normally engine driven for takeoff, hovering, and landing, and for forward flight through part of its speed range, and whose means of propulsion, consisting usually of conventional propellers, is independent of the rotor system.”
gyro horizon (aircraft flight instrument). A gyroscopic flight instrument that gives the pilot an artificial reference for the pitch and roll attitude of the aircraft. A gyroscope with an erection system that keeps it perpendicular to the earth’s surface controls a bar that remains parallel with the horizon. By referring to this instrument, the pilot can keep the aircraft level when the natural horizon is not visible.
gyroplane (type of aircraft). A type of rotorcraft whose main rotors are not connected to the engine except for the initial spin-up. Aerodynamic forces cause the main rotor to spin during normal flight. An autogiro is a form of gyroplane.
14 CFR Part 1: “A rotorcraft whose rotors are not engine driven, except for initial starting, but are made to rotate by action of the air when the rotorcraft is moving; and whose means of propulsion, consisting usually of conventional propellers, is independent of the rotor system.”