The Society of Flight Test Engineers 




Lt. Col. Timothy R. Jorris, USAF
Director, Hypersonic Combined Test Force (HCTF), Senior Member SFTE
Farid Rafla
USAF, Chief, Aerothermodynamics Branch, HCTF

Barry Reed
USAF, Chief Operations Engineer, HCTF

  Supersonic ramjet (Scramjet) propulsion is considered as the next logical step in airbreathing propulsion technology development. The two most notable research projects resulting from this philosophy are the X-43 Hyper-X and X-51A WaveRider programs. The X-51 is an unmanned scramjet demonstration aircraft designed and developed by the consortium of Air Force Research Laboratory, Defense Advanced Research Project Agency (DARPA), Boeing Integrated Defense Systems, Pratt & Whitney Rocketdyne and NASA. The aircraft was developed to meet the requirements of the USAF as part of the WaveRider program. The overall test objective-and problem to be solved- of the X-51A program was to demonstrate the scramjet engine, using endothermic hydrocarbon fuel, by accelerating a vehicle from boost to Mach 6+.
  There have been three successful X-51A flights. The first had the longest duration of scramjet engine operation. The second had an unstart, and the third had a fin malfunction. Overall, the flight tests have demonstrated the feasibility of a free-flying scramjet-powered vehicle. The tests show that the vehicle can successfully reach the required conditions for scramjet engine operation, autonomous operation, and sustainable supersonic combustion. The flight test preparation for these missions is extremely meticulous; this attention to detail will be presented to show the importance of proper planning for successful flight test. Lastly, the “fourth and final Boeing X-51A WaveRider hypersonic engine demonstrator in mid-2013” should allow new results and lessons learned to be presented.