Aerofoil: A winglike structure, flat or curved, designed to obtain reaction upon its surfaces from the air through which it moves.
Aerofoil section: A section of an aerofoil made by a plane parallel to the plane of symmetry of the aerofoil.
Aeroplane: See Airplane.
Aileron: A movable auxiliary surface, usually part of the trailing edge of a wing, the function of which is to control the lateral attitude of an airplane by rotating it about its longitudinal axis.
Aircraft: Any form of craft designed for the navigation of the air—airplanes, airships, balloons, helicopters, kites, kite balloons, ornithopters, gliders, etc.
Airplane: A form of aircraft heavier than air which has wing surfaces for support in the air, with stabilizing surfaces, rudders for steering, and power plant for propulsion through the air. This term is commonly used in a more restricted sense to refer to airplanes fitted with landing gear suited to operation from the land. If the landing gear is suited to operation from the water, the term “seaplane” is used. (See definition.)
Pusher.—A type of airplane with the propeller in the rear of the engine.
Tractor.—A type of airplane with the propeller in front of the engine.
Airship: A form of balloon, the outer envelope of which is of elongated form, provided with a propelling system, car, rudders, and stabilizing surfaces.
Nonrigid.—An airship whose form is maintained by the pressure of the contained gas assisted by the car-suspension system.