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The BMW 003 (full RLM designation BMW 109-003) was an early axial compressor turbojet engine produced by BMW AG in Germany during World War II. The 003 and the Junkers Jumo 004 were the only German turbojet engines to reach production during World War II. Work had begun on the design of the BMW 003 before its contemporary, the Jumo 004, but prolonged developmental problems meant that the BMW 003 entered production much later, and the aircraft projects that had been designed with it in mind were re-engined with the Jumo powerplant instead. The most famous case of this was the Messerschmitt Me 262, which used the 003 in two of the V-series prototypes and in the two experimental A-1b aircraft. The only production aircraft to use the BMW 003 were the Heinkel He 162 and the late C-series versions of the Arado Ar 234. About 500 BMW 003 engines were built in Germany, but very few were ever installed in aircraft. The engine also formed the basis for turbojet development in Japan during the war, and in France and the Soviet Union following the war. ==Design and development== The practicality of jet propulsion had been demonstrated in Germany in early 1937 by Hans von Ohain working with the Heinkel company. Recognising the potential of the invention, the Reich Air Ministry ((ドイツ語:Reichsluftfahrtministerium), abbreviated RLM) encouraged Germany's aero engine manufacturers to begin their own programmes of jet engine development, offering contracts to both Junkers and BMW for an engine capable of static thrust.〔Christopher, John. ''The Race for Hitler's X-Planes'' (The Mill, Gloucestershire: History Press, 2013), p.60.〕 The BMW 003 began development as a project of the Brandenburgische Motorenwerke (Brandenburg Motor Works, known as "''Bramo''"), under the direction of Hermann Östrich and assigned the RLM designation 109-003 (using the RLM's "109-" prefix, common to all jet and rocket engine projects). Bramo was also developing another turbojet, the 109-002. In 1939, BMW bought out Bramo, and in the acquisition, obtained both engine projects. The 109-002 had a very sophisticated contra-rotating compressor design intended to eliminate torque, but was abandoned in favour of the simpler engine, which in the end proved to have enough development problems of its own. Construction began late in the same year and the engine ran for the first time in August 1940,〔Gunston 1989, p.27.〕 but produced only thrust, just half what was desired.〔Christopher, p.60.〕 The first flight test took place in mid-1941, mounted underneath a Messerschmitt Bf 110. Problems continued, however, so delaying the program that while the Me 262 (the first aircraft intended to use the engine) was ready for flight-testing, there were no power plants available for it and it actually began flight tests with a conventional Junkers Jumo 210 piston engine in the nose. It was not until November 1941 that the Me 262 V1 was flown with BMW engines, which both failed during the test.〔Christopher, p.61.〕 The prototype aircraft had to return to the airfield on the power of the piston engine, which was still fitted. The general usage of the BMW powerplant was abandoned for the Me 262, except for two experimental examples of the plane known as the Me 262 A-1b. The Me 262A-1a production version used the competing Jumo 004 whose heavier weight required the wings to be swept back in order to move the center of gravity into the correct position. Work on the 003 continued anyway, and by late 1942 it had been made far more powerful and reliable. The improved engine was flight tested under a Junkers Ju 88 in October 1943 and was finally ready for mass production in August 1944. Completed engines earned a reputation for unreliability; the time between major overhauls (not technically a TBO) was about 50 hours.〔Christopher, p.76.〕 (The competing Jumo 004's was between thirty and fifty, and may have been as low as ten.)〔 Developments of the engine included the 003C, which raised thrust to , and the 003D, which raised it to , in addition to having eight compressor stages and two turbine stages.〔Christopher, p.73.〕 The only production aircraft to use the 003 were the Heinkel He 162, which fitted a modified "E" version of the engine, modified with ventral mounting points to allow it to be mounted atop the fuselage of an aircraft. The four-engined Arado Ar 234C variants were also designed to use the more available BMW jet engine.〔Christopher, pp.73-4.〕 The BMW 003 proved cheaper in materials than the company's own 801 radial, ''RM''12,000 to ''RM''40,000, and cheaper than the Junkers Jumo 213 inverted V12 piston engine at ''RM''35,000, but slightly more costly than the competing Junkers Jumo 004's ''RM''10000.〔Christopher, p.74.〕 Moreover, the 004 needed only 375 hours to complete (including manufacture, assembly, and shipping), compared to 1,400 for the 801.〔Christopher, p.75.〕 At Kolbermoor, location of the Heinkel-Hirth engine works, the Fedden Mission, led by Sir Roy Fedden, found jet engine manufacturing was simpler and required lower-skill labor and less sophisticated tooling than piston engine production; in fact, most of making of hollow turbine blades and sheet metal work on jets could be done by tooling used in making automobile body panels.〔Christopher, pp.74-5.〕 The lifetime of the combustors was estimated at 200 hours.〔 One late version of the engine added a small rocket motor (the BMW 109-718) at the rear and usually just above the exhaust of the engine, which added some thrust each for three to five minutes, for take off and short dashes.〔Christopher, p.124.〕 In this configuration, it was known as the BMW-003R and was tested, albeit with some serious reliability problems, on single prototypes for advanced models of the Me 262 (Me 262C-2b ''Heimatschützer II'' ),〔Christopher, p.125.〕 and He 162 (He 162E). Both prototypes flew under hybrid jet/rocket power during March 1945,〔 though records do not indicate the results of testing with the 162E. Only about 500 examples of the BMW 003 were built,〔 but the Fedden Mission postwar estimated total German jet engine production by mid-1946 could have reached 100,000 units a year, or more.〔 The 003 was intended for export to Japan, but working examples of the engine were never supplied. Instead, Japanese engineers used drawings and photos of the engine to design an indigenous turbojet, the Ishikawajima Ne-20. 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「BMW 003」の詳細全文を読む スポンサード リンク
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