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An artist's concept of the Air Force Research Laboratory/Boeing X-51A during flight. The X-51 WaveRider is an unmanned research scramjet for hypersonic flight. The X-51 program was a cooperative effort by the Air Force, the Defense Advanced Research Agency, NASA, Boeing and Pratt & Whitney Rocketdyne. The program was managed by the Aerospace Systems Directorate in the Air Force Research Laboratory. X-51 technology will be used in the AFRL's high-speed strike weapon, a Mach 5-plus missile that's scheduled to enter service in the mid-2020s.