The X-51A WaveRider (also known as Boeing X-51) is an unmanned hypersonic scramjet that is capable of flying through the atmosphere at speeds of 3600 mph or Mach 6. At these speeds, a passenger jet using the same technology can theoretically travel across the U.S. in 46 minutes. The WaveRider received its name because it uses shockwaves to add speeds and lift. Scramjet is a short term for "supersonic combustion ramjet," and there have been many efforts through the years to perfect scramjet-powered aircraft.

The first prototype of the WaveRider was tested in June 2011 through a captive flight attached to a B-52. However, the test failed to reach full power. A second test on August 14, 2012 saw the aircraft breaking apart shortly after launch due to a design flaw in one of the craft's control fins.