The Boeing X-51 is a scramjet demonstration vehicle for hypersonic (Mach 7, around 8,050 km/h) flight testing. The X-51A WaveRider program is a consortium of the US Air Force, DARPA, NASA, Boeing and Pratt & Whitney Rocketdyne. The program is managed by the Propulsion Directorate within the United States Air Force Research Laboratory (AFRL). The X-51 is a descendant of earlier efforts including the Advanced Rapid Response Missile Demonstrator and the liquid hydrocarbon-fuelled scramjet engine developed under the USAF’s HyTech program. The scramjet flight test vehicle was designated X-51 on 27 September 2005. The X-51 is carried aloft by a B-52 bomber and then launched with the aid of a solid rocket booster. The first flight of the X-51 is expected in 2009. DARPA had viewed X-51 as a stepping stone to Blackswift, a planned hypersonic demonstrator that was canceled in October 2008 In 2009 a total of 4 test flights are scheduled. The first flight of the X-51A is targeted for October 27, 2009 and Boeing has proposed to the Air Force Research Laboratory to extend the test flights from four to six. Aviation Week article. http://tinyurl.com/mgac42 Static model of the X-51 A pic of the model of the booster is attached.