Gas Vane

a device for controlling aircraft, rockets, spacecraft, and the like during those parts of a flight where air vanes are not effective. Gas vanes vary in design from plates that change the thrust direction of a gas flow to complicated guide vanes. In aircraft for vertical takeoff and landing, gas vanes are used during takeoff and landing conditions (until horizontal flight is achieved); in rockets and spacecraft they are used during the initial portions of a flight and for control in nonatmospheric conditions.