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The Boeing X-51 (also known as X-51 WaveRider) is an unmanned scramjet demonstration aircraft for hypersonic (Mach 6, approximately at altitude) flight testing. It completed its first powered hypersonic flight on 26 May 2010. After two unsuccessful test flights, the X-51 completed a flight of over six minutes and reached speeds of over Mach 5 for 210 seconds on 1 May 2013 for the longest duration hypersonic flight. The X-51 received the name "WaveRider" because it uses its shock waves to add compression lift. The program was a cooperative effort of the United States Air Force, DARPA, NASA, Boeing, and Pratt & Whitney Rocketdyne. The program was managed by the Aerospace Systems Directorate within the U.S. Air Force Research Laboratory (AFRL).〔(【引用サイトリンク】title= Successful Design Review and Engine Test Bring Boeing X-51A Closer to Flight )〕〔(【引用サイトリンク】title= New AFRL Aerospace Systems Directorate takes shape )〕 X-51 technology will be used in the High Speed Strike Weapon (HSSW), a Mach 5+ missile planned to enter service in the mid-2020s. ==Design and development== In the 1990s, the Air Force Research Laboratory (AFRL) began the HyTECH program for hypersonic propulsion. Pratt & Whitney received a contract from the AFRL to develop a hydrocarbon-fueled scramjet engine which led to the development of the SJX61 engine. The SJX61 engine was originally meant for the NASA X-43C, which was eventually canceled. The engine was applied to the AFRL's Scramjet Engine Demonstrator program in late 2003.〔Warwick, Graham. ("X-51A to demonstrate first practical scramjet" ). ''Flight International'', 20 July 2007.〕 The scramjet flight test vehicle was designated X-51 on 27 September 2005. In flight demonstrations, the X-51 is carried by a B-52 to an altitude of about and then released over the Pacific Ocean. The X-51 is initially propelled by an MGM-140 ATACMS solid rocket booster to approximately . The booster is then jettisoned and the vehicle's Pratt & Whitney Rocketdyne SJY61 scramjet accelerates it to a top flight speed near .〔( "Successful Design Review and Engine Test Bring Boeing X-51A Closer to Flight" ). Boeing, 1 June 2007. Retrieved: 28 July 2008.〕〔("X-51A Waverider flight planned for May 25" ). US Air Force, 20 May 2010. Retrieved: 20 May 2010.〕 The X-51 uses JP-7 fuel for the SJY61 scramjet, carrying some on board. DARPA once viewed X-51 as a stepping stone to Blackswift,〔Berger, Brian.("NASA Helping U.S. Air Force Gear Up for 2009 X-51 Flights" ). Space.com, 8 September 2008.〕 a planned hypersonic demonstrator which was canceled in October 2008.〔Trimble, Stephen. ("DARPA cancels Blackswift hypersonic test bed" ). Flight global, 13 October 2008.〕 In May 2013, the U.S. Air Force plans have X-51 technology applied to the High Speed Strike Weapon (HSSW), a missile similar in size to the X-51. The HSSW could fly in 2020 and enter service in the mid-2020s. It is envisioned to have a range of 500-600 nmi, fly at Mach 5-6, and fit on an F-35 or in the internal bay of a B-2 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「Boeing X-51」の詳細全文を読む スポンサード リンク
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