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The Lockheed Model 12 Electra Junior, more commonly known as the Lockheed 12 or L-12, is an eight-seat, six-passenger all-metal twin-engine transport aircraft of the late 1930s designed for use by small airlines, companies, and wealthy private individuals. A scaled-down version of the Lockheed Model 10 Electra, the Lockheed 12 was not popular as an airliner but was widely used as a corporate and government transport. Several were also used for testing new aviation technologies. ==Design and development== After Lockheed had introduced its 10-passenger Model 10 Electra, the company decided to develop a smaller version which would be better suited as a "feeder airliner" or a corporate executive transport.〔O'Leary 2001, p. 1.〕 At the same time, the U.S. Bureau of Air Commerce had also sensed the need for a small feeder airliner and announced a design competition for one. In order for a candidate to qualify for the competition, a prototype had to fly by June 30, 1936.〔O'Leary 2001, p. 3.〕〔Bowers 2000, p. 2.〕 Lockheed based its candidate, which it named the Model 12 Electra Junior, around a smaller, improved version of the Electra airframe. It would carry only six passengers and two pilots but would use the same Pratt & Whitney R-985 Wasp Junior SB radial engines as the main Electra version, the 10A.〔 This made it faster than the Electra, with a top speed of at .〔〔 Like the Electra, the Model 12 had an all-metal structure, trailing-edge wing flaps,〔 low-drag NACA engine cowlings, and two-bladed controllable-pitch propellers (later changed to constant-speed propellers).〔 It also had the Electra's twin tail fins and rudders, which were becoming a Lockheed trademark. The landing gear was a conventional tail-dragger arrangement, with the main wheels retracting backwards into the engine nacelles; as was often the case with retractable gear of the period, the wheel bottoms were left exposed in case a wheels-up emergency landing was necessary.〔Bowers 2000, p. 1.〕 As in the Electra and the Boeing 247, the Model 12's main wing spar passed through the passenger cabin; small steps were placed on either side of the spar to ease passenger movement.〔 The cabin had a lavatory in the rear.〔 Although the standard cabin layout was for six passengers, Lockheed also offered roomier, more luxurious layouts for corporate or private owners.〔〔 The new transport had its first flight on June 27, 1936,〔〔 three days before the competition deadline, at 12:12 PM local time, a time deliberately chosen for the Model 12's number.〔 As it turned out, the other two competition entries, the Beechcraft Model 18 and the Barkley-Grow T8P-1, weren't ready in time for the deadline, so Lockheed won by default. The "Electra Junior" name did not catch on in the way that the original Electra's name had. Most users simply referred to the aircraft by its model number, as the Lockheed 12.〔 The original Lockheed 12 version, with Wasp Junior engines, was the Model 12A.〔 Almost every Lockheed 12 built was a 12A or derived from the 12A. There was also a Model 12B, using Wright R-975-E3 Whirlwind radials, but only two of this model were built.〔 Although Lockheed had also announced a Model 12F, powered by Wright R-760 Whirlwind seven-cylinder radials, and a Model 12M, powered by Menasco six-cylinder inline engines,〔''Flight'' 1936, p. 148.〕 neither of these versions reached production. 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「Lockheed Model 12 Electra Junior」の詳細全文を読む スポンサード リンク
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