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The Boeing X-50A Dragonfly, formerly known as the Canard Rotor/Wing Demonstrator, was a VTOL rotor wing experimental unmanned aerial vehicle that was developed by Boeing and DARPA to demonstrate the principle that a helicopter's rotor could be stopped in flight and act as a fixed wing, enabling it to transition between fixed-wing and rotary-wing flight. The X-50A built upon the work of the Sikorsky S-72 X-Wing program of the 1980s by designing the vehicle as a multi-mode aircraft from the ground up. The X-50A was one of two projects funded by DARPA in its "Heliplane" program.〔〔(【引用サイトリンク】title=X-50 Dragonfly Canard Rotor/Wing (CRW) )〕 Neither of the two prototype aircraft ever successfully transitioned to full forward flight. DARPA withdrew funding for the X-50 program in late 2006 due to inherent design flaws.〔 ==Development== Boeing initially proposed using the CRW configuration to fill a requirement for a VTOL aircraft suitable for escorting the V-22 tiltrotor. The X-50A was a joint program between Boeing and DARPA, with each paying for half the development costs. The X-50A was powered by a single conventional turbofan engine. For rotary-wing mode, the engine's exhaust was diverted to nozzles in the tips of the rotor blades. When the aircraft transitioned to full forward flight, the engine exhaust was directed through a nozzle at the rear of the aircraft and the rotor was locked into a fixed position and functioned as a conventional wing.〔McKenna, James T. "One Step Beyond", ''Rotor & Wing'', February, 2007, page 54〕 Two proof-of-concept aircraft were built as part of the program. The X-50A's maiden flight took place on 24 November 2003. 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「Boeing X-50 Dragonfly」の詳細全文を読む スポンサード リンク
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