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The Douglas TBD Devastator was a torpedo bomber of the United States Navy, ordered in 1934, it first flew in 1935 and entered service in 1937. At that point, it was the most advanced aircraft flying for the Navy and possibly for any navy in the world. However, the fast pace of aircraft development quickly caught up with it, and by the time of the Japanese attack on Pearl Harbor the TBD was already outdated. The Devastator performed well in some early battles, but earned notoriety for its catastrophically poor performance in the Battle of Midway, in which the 41 Devastators launched during the battle produced zero successful torpedo hits and only six survived to return to their carriers. Vastly outclassed in both speed and maneuverability by the Mitsubishi Zero fighters they faced, the vast majority of the force was wiped out with little consequence except to distract the Zeros from the much more capable (and survivable) SBD Dauntless dive bombers that eventually sank four Japanese carriers and a heavy cruiser. Although a small portion of the Devastator's dismal performance was later attributed to the many well-documented defects in the US Mark 13 torpedo, the aircraft was immediately withdrawn from frontline service after Midway, being replaced by the Grumman TBF Avenger. ==Design and development== Ordered on 30 June 1934, and entered into a US Navy competition for new bomber aircraft to operate from its aircraft carriers, the Douglas entry was one of the winners of the competition.〔Doll 1967, p. 28.〕 Other aircraft ordered for production as a result of the competition included the Northrop BT-1 which would evolve into the SBD Dauntless, the Brewster SBA and the Vought SB2U Vindicator.〔 The XTBD Devastator, which flew for the first time on 15 April 1935, marked a large number of "firsts" for the US Navy.〔Gunston 1976, p. 66.〕 It was the first widely used carrier-based monoplane as well as the first all-metal naval aircraft, the first with a totally enclosed cockpit, the first with power-actuated (hydraulically) folding wings and in these respects the TBD was revolutionary.〔 A semi-retractable landing gear was fitted, with the wheels designed to protrude below the wings to permit a "wheels-up" landing which might limit damage to the aircraft. A crew of three was normally carried beneath a large "greenhouse" canopy almost half the length of the aircraft. The pilot sat in front; a rear gunner/radio operator took the rearmost position, while the bombardier occupied the middle seat. During a bombing run, the bombardier lay prone, sliding into position under the pilot to sight through a window in the bottom of the fuselage, using the Norden Bombsight.〔 The normal TBD offensive armament consisted of either a Bliss-Leavitt Mark 13 aerial torpedo or a bomb, to be carried semi-recessed into a fuselage bomb bay. Alternatively, three general-purpose bombs (one under each wing root and one inside the bomb bay), or twelve fragmentation bombs (six under each wing root), could be carried. This weapons load was often used when attacking Japanese targets on the Gilbert and Marshall Islands in 1942.〔Winchester 2004, p. 79.〕 Defensive armament consisted of a Browning machine gun for the rear gunner. Fitted in the starboard side of the cowling was either a or M2 Browning machine gun.〔 The powerplant was a Pratt & Whitney R-1830-64 Twin Wasp radial engine of , an outgrowth of the prototype's Pratt & Whitney XR-1830-60/R-1830-1 of .〔Mondey 2006, p. 128.〕 Other changes from the 1935 prototype included a revised engine cowling〔Taylor 1969, p. 485.〕 and raising the cockpit canopy to improve visibility.〔 The XTBD had a flat canopy that was replaced on production models by a higher, domed canopy over a rollover bar. Other than requests by test pilots to improve pilot visibility, the prototype easily passed its acceptance trials that took place from 24 April-24 November 1935 at NAS (Naval Air Station) Anacostia and Norfolk bases. After successfully completing torpedo drop tests, the prototype was transferred to the USS ''Lexington'' for carrier certification.〔Doll 1967, p. 29.〕 The extended service trials continued until 1937 with the first two production aircraft retained by the company exclusively for testing.〔Tillman 1973, p. 25.〕 A total of 129 of the type were purchased by the US Navy's Bureau of Aeronautics (BuAer), and starting from 1937, began to equip the carriers USS , , , , , and . In prewar use, TBD units were engaged in training and other operational activities and were gradually approaching the end of their useful service life with at least one aircraft being converted to target tug duty.〔Doll 1967, p. 32.〕 By 1940, the US Navy was aware that the TBD had become outclassed by the fighters and bombers of other nations and a replacement was in the works, but it was not yet in service when the US entered World War II. By then, attrition had reduced their numbers to just over 100 aircraft.〔Tillman and Lawson 2001, p. 56.〕 The US Navy assigned popular names to its aircraft in late 1941, and the TBD became the Devastator, although its nickname "torpecker" was commonly used.〔Tillman and Lawson 2001, p. 57.〕 The TBD is prominently featured in the 1941 film ''Dive Bomber''. 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 TBD Devastator」の詳細全文を読む スポンサード リンク
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