Unmanned Boeing X51 Waverider flight tests

The Boeing X51 WaveRider is a demonstration aircraft designed by combined effort of DARPA, United States Air Force, NASA, Boeing and Pratt & Whitney Rocketdyne and managed by United States Air Force Research Laboratory. 
The X-51 made its first captive flight on December 2009 on a B-52 plane. Then on 26 May 2010, it made its first flight and attained speeds greater than Mach 5 and an altitude of 70,000ft (i.e) 21,000m and a duration of 200 seconds. The above image shows the X51 under B-52’s wing at Edwards Air Force Base.
  • Length – 26 ft in (7.9m)
  • Empty Weight – 4,000 lb (1,814 kg)
  • Maximum speed – Mach 7+
  • Powerplant – Pratt & Whitney Rocketdyne SJY61
The X-51 is carried by B-52 up to an altitude of 50,000 feet (i.e) 15.2 kilometers and then released from the aircraft. At initial point after the release, X-51 is powered by an MGM-140 ATACMS solid rocket booser to Mach 4.5 before it is jettisoned. 
The the plane is propelled by Pratt & Whitney Rocketdyne SJY61 scramjet which increases the speed to Mach 6. The X-51 carries 270 lb (i.e) 120 kg onboard and uses JP-7 fuel for its scramjet engine.
It made its second flight on 13 June 2011 but the duration was short as the inlet was unable to start after reaching Mach 5. The third flight was conduced on 14 August 2012 to reach a flight duration of 300 seconds travelling more than 3,600 mph.

Animated video created by Pratt & Whitney Rocketdyne showing Boeing X-51 in flight test.

Credits: DARPA, United States Air Force, NASA, Boeing, Pratt & Whitney