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Airplanes Wallpapers have collection of desktop pictures from 640x480 and up to 1600x1200 pixels. An aircraft is any machine capable of atmospheric flight. Aircraft fall into two broad categories: Heavier than air aerodynes, including autogyros, helicopters and variants, and conventional fixed-wing aircraft: aeroplanes in Commonwealth English, airplanes in North American English. Fixed-wing aircraft generally use an internal-combustion engine and propeller or jet engine to provide thrust, which moves the craft forward through the air. The movement of air over the airfoil produces lift, which allows the aircraft to fly. Exceptions are gliders which have no engines and gain their thrust from gravity and thermal currents. That is, in order to maintain their forward speed they must descend in relation to the air (but not necessarily in relation to the ground). Helicopters and autogyros use a spinning rotor (a rotary wing) to provide both lift and thrust. The abbreviation VTOL is applied to aircraft other than helicopters that can take off or land vertically. Similarly, STOL stands for Short Take Off and Landing. Lighter than air aerostats: balloons and airships. Aerostats float in air in the same way that a ship floats in water, by displacing the air around the craft with a lighter gas (helium or hydrogen),or hot air. The distinction between a balloon and an airship is that an airship has some means of controlling forward motion and steering, while balloons simply drift with the wind. See also: List of aviation, aerospace and aeronautical terms There are several ways to classify aircraft. Below, we describe classifications by design, propulsion and usage. (source: wikipedia)