Propeller—See “Air-Screw.”
Propeller, Tractor—An air-screw mounted in front of the main lifting surface.
Propeller, Pusher—An air-screw mounted behind the main lifting surface.
Pusher—An aeroplane of which the propeller is mounted behind the main lifting surface.
Pylon—Any V-shaped construction from the point of which wires are taken.
Power—Rate of working.
Power, Horse—One horse-power represents a force sufficient to raise 33,000 lbs. 1 foot in a minute.
Power, Indicated Horse—The I.H.P. of an engine is a measure of the rate at which work is done by the pressure upon the piston or pistons, as distinct from the rate at which the engine does work. The latter is usually termed “brake horse-power,” since it may be measured by an absorption brake.
Power, Margin of—The available quantity of power above that necessary to maintain horizontal flight at the optimum angle.
Pitot Tube—A form of air-speed indicator consisting of a tube with open end facing the wind, which, combined with a static pressure or suction tube, is used in conjunction with a gauge for measuring air pressures or velocities. (No. 1 in diagram.)