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The Bell XP-77 development was initiated by the United States Army Air Forces during World War II to produce a simplified "lightweight" fighter aircraft using so-called "non-strategic" materials. Despite being innovative, the diminutive prototype proved tricky to handle and the project was canceled when the XP-77 did not deliver its projected performance. ==Design and development== The Tri-4 (Company designations, later changed to D-6 〔Schrader 1999, p. 19.〕) project with the Bell Aircraft Corporation was initiated in October 1941. Originally a design study to meet the USAAF specifications for a "very light" interceptor, the XP-77 was intended to be a small, light fighter much in the mold of the 1930s Thompson Trophy air racers. On 16 May 1942, the USAAF recommended the construction and testing of 25 XP-77s.〔 The aircraft featured a single-engine, low-wing monoplane with mainly wood construction, equipped with tricycle landing gear, a Bell trademark that bestowed good ground handling. A sleek bubble canopy also provided all-round visibility (except forward due to the extended nose); a key requirement for a fighter.〔Winchester 2005, p. 187.〕 While originally conceived using an air-cooled 500 hp Ranger XV-770-9 12-cylinder engine with a supercharger, the prototypes were delivered with the non-supercharged XV-770-7 engine due to engine development delays. With the anticipated delivery time of the original engine delayed for one and a half years, Bell proposed that seven XP-77s be built using the seven XV-770-7 engines then available.〔 The planned armament was one Hispano 20 mm cannon firing through the propeller hub (much like the larger caliber 37 mm ''moteur-canon'' of the SPAD S.XII) and two 0.5 inch Browning machine guns, with the option of either a 300 lb bomb or 325 lb depth charge with the deletion of the cannon armament. The mock-up inspection on 21–22 September 1942 produced some concerns from both the manufacturer and the USAAF inspection team. Weight had crept up beyond 3,700 lb design limit but delays in the program were experienced when the company resorted to sub-contracting the wooden construction while the ongoing production at the Bell facilities did not allow for the XP-77 to take priority for research and development. Bell asked and received permission to reduce the production run of aircraft to two prototypes.〔Schrader 1999, p. 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「Bell XP-77」の詳細全文を読む スポンサード リンク
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