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The essential components of anairplane are a wing system to sustain it in flight, tail surfaces to stabilize the wing, movable surfaces (ailerons, elevators, and rudders) to control the attitude of the machine in flight, and a powerplant to provide the thrust to push the craft through the air.
An enclosed body (fuselage) houses the crew, passengers, and cargo, as well as the controls and instruments used by the navigator. Anairplane also requires a support system (such as wheels or pontoons) when it is at rest on a surface and during takeoff and landing.
Most airplanes in use today are monoplanes (i.e., aircraft with asingle pair of wings). They are termed high-wing when the wing is attached at the top of the fuselage, midwing when it extends from or near the centre of fuselage section, and low-wing when the wingstructure fastens to the fuselage structure at the bottom. The multiplane with two or more horizontal wing systems, one above the other, connected by a series of struts and wires, has virtuallydisappeared.
The few biplanes still in service are used mainly for sport flying or for agricultural crop dusting. Monoplanes may be characterized by the planform (top view) of their wings, which may berectangular, tapered, swept-back, or delta. A so-called variable-geometry concept incorporating adjustable sweepback is a compromise to obtain good high- and low-speed characteristics from the same...