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A gas-turbine is a form of engine in which a continuous stream of hot gases is directed against the blades of a turbine, causing it to turn. In most cases the gas, usually air, is first compressed in a compressor before passing into combustion chambers, where a portion of the gas is mixed with fuel and burned. The rest of the gas bypasses the combustion chamber and mixes with the hot gases emerging after combustion. This is then forced through nozzles to drive a turbine. Part of the power from this turbine is used to drive the compressor; the remaining power can be used in various ways, depending on the function of the engine: it may drive the propeller shaft of a turboprop aircraft or ship, the drive-shaft of a locomotive, or an electric generator. Alternatively, a turbine just big enough to drive the compressor can be used, and the remaining energy of the hot exhaust gases used to give a high-speed exhaust jet and hence a forward thrust; this is the jet engine. Gas-turbines are used in electricity generation for standby and peak-load service, in portable power plants, and in combined-cycle power generation. The high power-to-weight ratio of gas-turbines has led to their use in aeroplanes, and also in diesel locomotives and naval vessels.
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A jet engine is a form of gas-turbine engine used in aircraft, in which the thrust is generated by a jet of exhaust gas discharged from a nozzle at the rear of the engine.
Jet engines were developed concurrently in the UK and in Germany. Whittle's centrifugal flow turbojet was patented in 1930 and first tested later in the same year. The first jet aeroplane to fly was the German Heinkel He 178 in 1939, powered by an engine designed by von Ohain. In a turbojet, air is taken into the engine and compressed, then mixed with fuel and burnt. The combustion gases then pass through a turbine, the power from which drives the compressor, after which the remaining energy in the gas is converted to kinetic energy in the exhaust cone and propelling nozzle, and ejected as a high- velocity jet. The configuration of the propelling nozzle is critical for maximum efficiency at a given speed. Turbojets are most efficient at high speeds: for speeds below 800 km/h a more efficient type of engine is the turboprop. This works on the same principle as the turbojet, but most of the energy of the combustion gases drives the turbine, which is used to power a propeller as well as the compressor. A small amount of forward thrust is also obtained from the
exhaust gases. A major use of turboprop engines is in helicopters. In the bypass jet engine two air compressors, one low- pressure and one high-pressure, are used. After passage through the first, low-pressure compressor, part of the air intake bypasses the combustion chamber and turbine. The combination of this cold air jet and the hot exhaust jet gives a much larger mass of air and therefore increased thrust, without an increase in fuel consumption. This principle is taken even further in the turbofan engine, which incorporates a large fan to accelerate still more air outside the engine proper, as well as using the bypass principle. Current research priorities include the reduction of polluting emissions from jet engines, and the development of ceramic engine components, which are lighter and can work at higher temperatures than metals.
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The Aero Commander Turbo Commander is an American executive pressurised transport aircraft first flown in 1964. The Aero Commander Turbo Commander is a high-wing cantilever monoplane powered by two AiResearch TPE 331-43 turboprop engines providing a top speed of 459 kmh and a range of 1610 km. The Aero Commander Turbo Commander carries a pilot and four passengers in a separate cabin as standard, with optional layouts for up to eleven passengers.
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The Aero Commander Turbo II Commander is an American executive transport aircraft first flown in 1964. The Aero Commander Turbo II Commander is a pressurised version of the Aero Commander Grand Commander, and is powered by two AiResearch TPE 331-43 turboprop engines providing a top speed of 450 kmh and a range of 1690 km fully laden. The Aero Commander Turbo II Commander carries eight passengers as standard, but is otherwise the same as the Aero Commander Grand Commander.
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The AIDC T-1 Chung-tsing is an American-designed Taiwanese two-seater basic/advanced fling trainer with limited armament training and ground attack capabilities. The AIDC T-1 entered military service in 1976 and is powered by a Textron Lycoming T53-L-701 turboprop providing a top speed of 685 kmh and a range of 2010 km. The AIDC T-1 carries no fixed armaments but has provision for disposable stores to be carried on two under-wing hard points.
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The Antonov An-24 (Coke) is a 52-seater a short-range twin turboprop aeroplane developed during the 1950s, similar to the Fokker F 27 Friendship. The An-24 is powered by two ZMDB Progress AI-24A turboprops providing a top speed of 498 kmh and a range of 640 km fully laden, increasing to 3000 km empty. The An-24 is fitted with high wings to minimize the risk of propeller damage on the USSR's many unsurfaced landing strips. Aeroflot's vast fleet contains more An-24s than any other airliner; over 1,000 fire-fighting, aerial survey and passenger versions have been built. The An-24 was adopted for military service in 1962 as a short-range utility freight transport aircraft. The military version of the An-24 carries a flight crew of five and up to 38 troops or 30 paratroops or 24 litters and one attendant or 4612 kg of freight in the hold.
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The Armstrong Whitworth AW 650 Argosy (later Hawker Siddeley Argosy 650)was a British large-capacity civil freight transport aircraft first flown in 1959. The Armstrong Whitworth AW 650 was a shoulder-wing cantilever monoplane powered by four Rolls-Royce Dart Mk 526 turboprop engines providing a top speed of about 475 kmh and a range of 4830 km. The Armstrong Whitworth AW 650 carried a crew of two or three in a raised flight deck above the main cabin.
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The Armstrong Whitworth AW 660 (later Hawker Siddeley Argosy 660) was a British large-capacity military transport aircraft first flown in 1959. The Armstrong Whitworth AW 660 was a shoulder-wing cantilever monoplane powered by four Rolls-Royce Dart Mk 526 turboprop engines providing a top speed of about 475 kmh and a range of 4830 km. The Armstrong Whitworth AW 660 carried a crew of two or three in a raised flight deck above the main cabin.
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The Armstrong Whitworth AW 670 was a British car ferry transport aircraft first flown in 1959. The Armstrong Whitworth AW 670 was a shoulder-wing cantilever monoplane powered by four Rolls-Royce Dart Mk 526 turboprop engines providing a top speed of about 475 kmh and a range of 4830 km. The Armstrong Whitworth AW 670 carried a crew of two or three in a raised flight deck above the main cabin which could accommodate six cars and thirty passengers on two decks.
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The Armstrong Whitworth AW 671 Airbus was a British large-capacity civil passenger aircraft first flown in 1959. The Armstrong Whitworth AW 671 was a shoulder-wing cantilever monoplane powered by four Rolls-Royce Dart Mk 526 turboprop engines providing a top speed of about 475 kmh and a range of 4830 km. The Armstrong Whitworth AW 671 carried a crew of two or three in a raised flight deck above the main cabin which had accommodation for 96 passengers on a lower deck and 30 in an upper deck.
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The Probert Encyclopaedia was designed, edited and programed by
Matt and Leela Probert
©1993 - 2009 The Probert Encyclopaedia
Southampton, United Kingdom
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