Any vehicle capable of travelling in the Earth's atmosphere. By far the most common aircraft is the airplane (aeroplane or plane). The airplane is a heavier-than-air flying machine that depends upon fixed wings for lift in the air, as it moves under the thrust of its engines. This thrust may be provided by an airscrew (propeller) turned by a piston or turbine engine, or by the exhaust gases of a jet engine or rocket motor. Gliders differ from planes only in their sole dependence upon air currents to keep them airborne. The main body of a plane is the fuselage, to which are attached the wings and tail assembly. Engines may be incorporated into (or slung below) the wings, but are sometimes mounted on the fuselage towards the tail or, as in some fighter aircraft, built into the fuselage near the wings. The landing gear (undercarriage), with its heavy wheels and stout shock absorbers, is usually completely retractable into the wings or fuselage. High-speed fighters have slim, often swept-back or adjustable wings that minimize air resistance (drag) at high speeds. Heavy air freighters need broader wings in order to achieve the necessary lift at take-off. A delta wing is a broad wing, or fuselage extension, that is aerodynamically suited for both large and small high-speed planes. A plane is steered by flaps and ailerons on the wings, and rudder and elevators on the tail assembly. This deflects the pressure of air on the aerofoil surfaces, causing the plane to rise or descend, to bank (tilt) or swing and turn in the air. Radar systems aid navigation and an autopilot keeps the aircraft on a steady, fixed course. Pressurized cabins allow passenger planes to fly at heights exceeding 10,000m (33,000ft). See also airship; aerodynamics; aerofoil; balloon; gliding; helicopter
See aerodynamics ; aerofoil ; aeronautics ; aircraft ...
pronunciation (1907) : a powered heavier-than-air aircraft with fixed wings from which it derives most of its lift
n 1 US and Canadian a heavier-than-air powered flying vehicle with fixed wings Also called: aeroplane