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The PZL MD-12 was a Polish four-engined short-range passenger and civil utility aircraft of the 1960s, which remained in a prototype stage. ==Design and development== The aircraft was development as a successor to the Lisunov Li-2 on short domestic routes for LOT Polish Airlines. The plane was designed by a design bureau led by Franciszek Misztal in the Aviation Institute (''Instytut Lotnictwa''). The first design work started in 1954 (under the designation FM-12) and the final design MD-12 appeared in 1956, after Leszek Dulęba had joined (the designation apparently came from Misztal-Dulęba). Initially it was to be powered with two Soviet 615 hp ASh-21 engines, but because their production stopped, a four-engine configuration was chosen, with Polish 315 hp WN-3 engines. In December 1957 the bureau was moved to the OKL centre (''Ośrodek Konstrukcji Lotniczych'' - Aviation Designs' Centre), created in the WSK-Okęcie factory. The first prototype flew first on 21 July 1959 (registration ''SP-PAL''), the second prototype, designated MD-12P (''SP-PBD''), and fitted with complete passenger cab, on 7 January 1961. There was a third airframe built for static trials. The plane underwent state trials in 1961, and the second prototype was evaluated by LOT Airlines in August–September 1961. The passenger variant was evaluated as quite successful, being easier to fly, than the Ilyushin Il-14 and more economical, but it was not produced because LOT found it unprofitable to order special planes for domestic routes. The small production that would result would increase costs. Instead, less modern airliners were switched from international to domestic routes. It was next decided to build an aerial photography variant MD-12F. It was fitted with several cameras and other equipment, including a darkroom. The fuselage nose was glazed, with a navigator post. Span increased to 23.6 m by adding longer wingtips. The MD-12F flew first on 21 July 1962 (apparently dates of MD-12 prototypes' flights were adjusted to add splendour to communist Poland's national holiday, 22 July). It carried the registration ''SP-PBL''. The aerial photography variant was successful and countries, like the USSR, Hungary, Romania and Pakistan were interested in it, but its development was ceased along with a crash of the first MD-12 prototype on 17 September 1963 near Grójec. The plane crashed due to flutter of tail control surfaces and a crew of 5 were killed. 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「PZL MD-12」の詳細全文を読む スポンサード リンク
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