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Aerodynamics And Aircraft

  Aerodynamics (Greek, ‘study of the power of air’) is the study of the flow of air or gases in motion. The main application of aerodynamics is in aviation. Aerodynamic analysis is also used to study the effect that wind will have on such artificial structures as bridges and tower blocks, on the flow of steam in turbines, or on the operation of wind-power generators.

The concept of flight was established by Leonardo da Vinci, who made sketches of devices similar to the modern helicopter and hang-glider. Although Leonardo\'s ideas were well ahead of their time, they were doomed to failure, as the principles of aerodynamics were unknown.

Aircraft flight is based upon the presence of four forces: thrust, drag, gravity and lift. As long as the forces of thrust are greater than drag, and lift is greater than gravity, the aircraft will stay up and move in the air. Thrust is provided by the engines and the lift is created by the wings of the aircraft. The lift is generated by increasing the pressure below the wing and decreasing the pressure above it by the shape of the upper and lower surfaces of the wing and its inclination to the direction of flight. These two forces combine to overcome gravity, and so make flight possible.

The first man-made flight took place, not in an aircraft, but by a balloon. The flight was made by the Montgolfier brothers in 1783. Initially hydrogen, which is the lightest known gas, was used to fill the balloon. Hot air was found to be cheaper and now helium is used for preference. Their flight was to herald the race to become the first man to fly. Work by people such as Otto Lilienthal, who constructed and flew gliders, opened up the way for first powered flight, which was achieved by the Wright brothers in 1903 at Kitty Hawk, North Carolina (the flight lasted just 12 seconds).

The aircraft remained in its infancy for the next 30 years as new developments took place. One major requirement was a light, reliable engine with good fuel economy, and the other was the availability of light material of suitable strength for the structure. During this time, the aircraft was given a wider and wider role, from delivering post to reconnaissance missions during World War I. It was also used for entertainment, especially with long-distance flights taking place in the hope that the pilot would collect major prizes. In 1927, Charles Lindbergh\'s single-handed crossing of the Atlantic was seen as a major technological breakthrough, and laid the foundations for long haulage transportation of people and goods.

By the start of World War II, the aircraft was at such a stage that its use in warfare was of paramount importance. It was also developed on the commercial side with the setting up of the first airline, KLM, in 1923. The original concepts of the use of the propeller driven by a piston engine remained until World War II when jet propulsion for military aeroplanes was first introduced. Commercial aeroplanes continued to use propellers driven by gas turbines until the introduction of the first commercial jet aircraft in 1949, the de Havilland Comet. Its introduction was to transform people\'s way of travelling, as foreign ports of call became more accessible. AA

See also jet engines.Further reading J Christie, High Adventure: the First 75 years of Civil Aviation.



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