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A jet aircraft (or simply jet) is an aircraft (nearly always a fixed-wing aircraft) propelled by jet engines (jet propulsion). Whereas the engines in propeller-powered aircraft generally achieve their maximum efficiency at much lower speeds and altitudes, jet engines and aircraft achieve maximum efficiency (see specific impulse) at speeds close to or even well above the speed of sound. Jet aircraft generally cruise at faster than about M 0.8 (609 mph, 981 km/h or 273 m/s) at altitudes around or more. Frank Whittle, an English inventor and RAF officer, developed the concept of the jet engine in 1928,〔http://www.cwn.org.uk/heritage/people/whittle/biography.html〕 Hans von Ohain in Germany, a decade later developed the concept independently at the end of the 1930s. He wrote in February 1936 to Ernst Heinkel, telling him of the design and its possibilities. However, it can be argued that the English engineer A. A. Griffith, who published a paper in July 1926 on compressors and turbines, also deserves credit. ==History== A number of jet powerplants were suggested from the first instances of powered flight. René Lorin, Morize, Harris proposed systems for creating a jet efflux.〔(Jet Propulsion of Aircraft Part III ) G Geoffrey Smith ''Flight'' September 25th 1941〕 In 1910 the Romanian inventor Henri Coandă filed a patent on a jet propulsion system which used piston-engine exhaust gases to add heat to an otherwise pure air stream compressed by rotating fan blades in a duct. Rocket-powered jet aircraft were pioneered in Germany. The first aircraft to fly under rocket power was the Lippisch Ente, in 1928.〔("Lippisch Ente." ) ''The Internet Encyclopedia of Science: Experimental Aircraft.'' Retrieved: 26 September 2011.〕 The Ente had previously been flown as a glider. The next year, in 1929, the Opel RAK.1 became the first purpose-built rocket plane to fly. The "turbojet", was invented in the 1930s, independently by Frank Whittle and later Hans von Ohain. The first turbojet aircraft to fly was the Heinkel He 178 V1 first prototype of the German Air Force, the ''Luftwaffe'', on August 27, 1939 in Rostock (Germany).〔Warsitz, Lutz: (''The First Jet Pilot – The Story of German Test Pilot Erich Warsitz'' (p. 125), Pen and Sword Books Ltd., England, 2009 )〕 The first flight of a jet engined aircraft to come to popular attention was the Italian Caproni Campini N.1 motorjet prototype that flew on August 27, 1940.〔(''Flight'' 28 August 1941 )〕 It was the first jet aircraft recognised by the Fédération Aéronautique Internationale (at the time the German He 178 program was still kept secret). Campini had proposed the motorjet in 1932. The British experimental Gloster E.28/39 first took to the air on May 15, 1941, powered by Sir Frank Whittle's turbojet.〔("No Airscrew Necessary..." ) ''Flight''(flightglobal.com), 27 October 1949 p554〕 The United States produced the Bell XP-59A using two examples of a version of the Whittle engine built by General Electric, which flew on October 1, 1942. The Meteor was the first production jet as it entered production a few months before the Me 262. The first operational jet fighter was the Messerschmitt Me 262,〔Hecht, Heinrich. ''The World's First Turbojet Fighter – Messerschmitt Me 262''. Atglen, Pennsylvania: Schiffer Publishing, 1990. ISBN 0-88740-234-8.〕 made by Germany during late World War II. It was the fastest conventional aircraft of World War II – although the rocket-powered Messerschmitt Me 163 ''Komet'' was faster. It had first flown in 1941 but mass production started in 1944 with the first squadrons operational that year, too late for a decisive effect on the outcome of the war. About the same time, mid 1944, the United Kingdom's Gloster Meteor was being committed to defence of the UK against the V-1 flying bomb – itself a pulsejet-powered aircraft and direct ancestor of the cruise missile– and then ground-attack operations over Europe in the last months of the war. In 1944 Germany introduced into service the Arado Ar 234 jet reconnaissance and bomber, though chiefly used in the former role, with the Heinkel He 162 ''Spatz'' single-jet light fighter premiering as 1944 ended. USSR tested its own Bereznyak-Isayev BI-1 in 1942, but the project was scrapped by Joseph Stalin in 1945. The Imperial Japanese Navy also developed jet aircraft in 1945, including the Nakajima J9Y Kikka, a modified, and slightly smaller version of the Me 262 that had folding wings. By the end of 1945, the US had introduced their next jet fighter, the Lockheed P-80 Shooting Star into service and the UK its second fighter design, the de Havilland Vampire. The US introduced the North American B-45 Tornado, their first jet bomber, into service in 1948. Although capable of carrying nuclear weapons it was used for reconnaissance over Korea. On November 8, 1950, during the Korean War, United States Air Force Lt. Russell J. Brown, flying in an F-80, intercepted two North Korean MiG-15s near the Yalu River and shot them down in the first jet-to-jet dogfight in history. The UK put the English Electric Canberra into service in 1951 as a light bomber. It was designed to fly higher and faster than any interceptor. BOAC operated the first commercial jet service, from London to Johannesburg, in 1952 with the de Havilland Comet jetliner. This highly innovative aircraft travelled far faster and higher than the propeller aircraft, was much quieter, smoother, and had stylish blended wings containing hidden jet engines. However, due to a design defect, and use of aluminum alloys, the aircraft suffered catastrophic metal fatigue which lead to several crashes.〔Jet! When Britain Ruled the Skies - BBC〕 The series of crashes gave time for the Boeing 707 to enter service in 1958 and this came to dominate the market for civilian airliners. The underslung engines were found to be advantageous in the advent of a propellant leak, and so the 707 looked rather different from the Comet: the 707 has a shape that is closer to modern aircraft. Turbofan aircraft began entering service in the 1950s and 1960s, bringing far greater fuel efficiency, and this is the type of jet in widespread use today. The Tu-144 supersonic transport was the fastest commercial jet plane at Mach 2.35 (1,555 mph, 2,503 km/h). It went into service in 1975, but soon stopped flying. The Mach 2 Concorde aircraft entered service in 1976 and flew for 27 years. The fastest military jet plane was the SR-71 Blackbird at Mach 3.35 (2,275 mph, 3,661 km/h). 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Jet aircraft」の詳細全文を読む スポンサード リンク
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