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The Douglas A-20 Havoc (company designation DB-7) was an American attack, light bomber, intruder aircraft of World War II. It served with several Allied air forces, principally the United States Army Air Forces (USAAF), the Soviet Air Forces (''VVS''), Soviet Naval Aviation (''AVMF'') and the Royal Air Force (RAF) of the United Kingdom. Soviet units received more than one in three (2,908 aircraft) of the DB-7s ultimately built. It was also used by the air forces of Australia, South Africa, France, and the Netherlands during the war, and by Brazil afterwards.〔Parker 2013, pp. 11, 18-19.〕 In British Commonwealth air forces, bomber/attack variants of the DB-7 were usually known by the service name Boston, while night fighter and intruder variants were usually known as Havoc. An exception to this was the Royal Australian Air Force, which referred to all variants of the DB-7 by the name Boston.〔Crick, Darren. ("RAAF A28 Douglas A-20A/C/G Boston". ) ''ADF Aircraft Serial Numbers'', 2009, Retrieved: 24 January 2013.〕 The USAAF referred to night fighter variants as P-70. ==Design and development== In March 1937, a design team headed by Donald Douglas, Jack Northrop and Ed Heinemann produced a proposal for a light bomber powered by a pair of 450 hp (336 kW) Pratt & Whitney R-985 Wasp Junior radial engines mounted on a Shoulder wing. It was estimated that it could carry a 1,000 lb (454 kg) bomb load at 250 mph (400 km/h). Reports of aircraft performance from the Spanish Civil War indicated that this design would be seriously underpowered, and it was subsequently cancelled. In the autumn of the same year, the United States Army Air Corps issued its own specification for an attack aircraft. The Douglas team, now headed by Heinemann, took the Model 7A design, upgraded with 1,100 hp (820 kW) Pratt & Whitney R-1830 Twin Wasp engines, and submitted the design as the Model 7B. It faced competition from the North American NA-40, the Stearman X-100 and the Martin 167F. The Model 7B was maneuverable and fast, but did not attract any US orders. The model did, however, attract the attention of a French Purchasing Commission visiting the United States. The French discreetly participated in the flight trials, so as not to attract criticism from American isolationists. The Air Corps, which controlled the aircraft's development, but had been excluded from negotiations between the French, the Production Division, and the Navy's Bureau of Aeronautics, was directed by the White House on 19 January 1939 to release the DB-7 for assessment in contradiction of its own regulations. The "secret" was revealed when the Model 7B crashed on 23 January while demonstrating single-engine performance. The French were still impressed enough to order 100 production aircraft, with the order increased to 270 when the war began. Sixteen of those had been ordered by Belgium for its ''Aviation Militaire''. Although not the fastest or longest-range aircraft in its class, the Douglas DB-7 series distinguished itself as a tough, dependable combat aircraft with an excellent reputation for speed and maneuverability. In a report to the British Aeroplane and Armament Experimental Establishment (AAEE) at RAF Boscombe Down, test pilots summed it up as: "has no vices and is very easy to takeoff and land ... The aeroplane represents a definite advantage in the design of flying controls ... extremely pleasant to fly and manoeuvre."〔Gann 1971, p. 7.〕 Ex-pilots often consider it their favorite aircraft of the war due to the ability to toss it around like a fighter.〔Winchester 2005, p. 72.〕 The Douglas bomber/night fighter was extremely adaptable and found a role in every combat theater of the war, and excelled as a true "pilot's aeroplane".〔Taylor 1969, p. 489.〕 When DB-7 series production finally ended on 20 September 1944, a total of 7,098 had been built by Douglas and a further 380 by Boeing. Douglas redesigned its Santa Monica plant to create a mechanized production line to produce A-20 Havocs. The assembly line was over a mile long (6,100 feet), but by looping back and forth, fitted into a building that was only 700 feet long. Man-hours were reduced by 50% for some operations. Production tripled.〔Parker 2013, pp. 7-13, 16, 18-19.〕 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「Douglas A-20 Havoc」の詳細全文を読む スポンサード リンク
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