page_title: Boeing X-51 Waverider
section_title: Design and development
hierarchical_section_title: Boeing X-51 Waverider / Design and development
caption_attribution_description: English: The X-51A WaveRider hypersonic flight test vehicle was uploaded to an Air Force Flight Test Center B-52 for fit testing at Edwards Air Force Base on July 17. Two B-52 flights, one captive carriage and one dress rehearsal, are planned this fall prior to the X-51's first Mach 6 plus scramjet flight over the Pacific Ocean scheduled in December. The Air Force Research Laboratory, DARPA, Pratt &amp; Whitney Rocketdyne, and Boeing are partnering on the X-51A technology demonstrator program.
context_page_description: The Boeing X-51 Waverider is an unmanned research scramjet experimental aircraft for hypersonic flight at Mach 5 and an altitude of 70,000 feet. The aircraft was designated X-51 in 2005. 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 powered hypersonic flight.
  Waverider refers in general to aircraft that take advantage of compression lift produced by their own shock waves. The X-51 program was a cooperative effort by 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. X-51 technology is proposed for use in the High Speed Strike Weapon, a Mach 5+ missile which could enter service in the mid-2020s.
context_section_description: 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.  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 50,000 feet (15 km; 9.5 mi) and then released over the Pacific Ocean.  The X-51 is initially propelled by an MGM-140 ATACMS solid rocket booster to approximately Mach 4.5 (3,000 mph; 4,800 km/h). The booster is then jettisoned and the vehicle's Pratt & Whitney Rocketdyne SJY61 scramjet accelerates it to a top flight speed near Mach 6 (4,000 mph; 6,400 km/h).  The X-51 uses JP-7 fuel for the SJY61 scramjet, carrying some 270 lb (120 kg) on board.
caption: X-51A under the wing of a B-52 at Edwards Air Force Base, July 2009
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