The X-51A WaveRider is an unmanned, autonomous hypersonic flight test vehicle developed through collaboration between the US Air Force, DARPA, Pratt & Whitney Rocketdyne, and Boeing. It uses a JP-7 fueled scramjet engine to demonstrate sustained hypersonic flight between Mach 4.5 to 6.5. The first flight test in 2010 set a record by maintaining Mach 5 speeds for 143 seconds. Subsequent tests in 2011 and 2012 encountered anomalies and the vehicles were lost. One X-51A vehicle remains for potential future testing.

1. Backgrounder
Boeing Defense, Space & Security
P.O. Box 516
St. Louis, MO 63166
www.boeing.com
X-51A WaveRider
Description and Purpose: The X-51A WaveRider is an unmanned, autonomous
supersonic combustion, ramjet-powered hypersonic flight-test demonstrator for the U.S.
Air Force. The X-51A demonstrates a scalable, robust endothermic hydrocarbon-fueled
scramjet propulsion system in flight, as well as high temperature materials,
airframe/engine integration and other key technologies within the hypersonic range of
Mach 4.5 to 6.5.
Customer(s):
The X-51A WaveRider Scramjet Engine Demonstrator program is a collaborative effort
of the U.S. Air Force Research Laboratory, the Defense Advanced Research Projects
Agency (DARPA), Pratt & Whitney Rocketdyne and Boeing to demonstrate hypersonic
flight capability.
The Air Force Research Laboratory manages this program. Vehicle integration is
performed by Boeing Advanced Network & Space Systems, headquartered in
Huntington Beach, Calif. Pratt & Whitney Rocketdyne is the propulsion system provider.
Length: Full stack 25 feet; Cruiser 14 feet; Interstage 5 feet; Solid rocket booster 6 feet
Power Plant: JP-7 fueled/cooled SJY61 supersonic combustion ramjet
Weight: Approx. 4,000 pounds
Fuel Capacity: Approx. 270 pounds JP-7 (kilograms)
Speed: 3,960+ miles per hour (@ Mach 6)
Range: 400+ nautical miles
Ceiling: 70,000 + feet
Background:
During its first historic flight test in May 2010, after being released from a B-52, the solid
rocket booster ignited and took the X-51A to approximately Mach 4.5, at which point the
scramjet engine took over and continuously accelerated the vehicle to a flight speed of
approximately Mach 5.0 for 143 seconds. The test was the longest of its kind and
provided significant hypersonic data.
The second flight test vehicle flew in June 2011 and collected significant flight test data
before the mission ended prematurely. After being dropped from a B-52 off the coast of

2. California, the vehicle encountered a problem while nearing speeds of approximately
Mach 5. The hypersonic vehicle attempted to restart several times and continued to
orient itself to optimize engine start conditions before flying into the ocean as originally
planned.
The third X-51A Waverider test vehicle was successfully launched from an Air Force B-
52 bomber over Point Mugu Naval Air Warfare Center Sea Range in August 2012.
During that test, the X-51A safely separated from the B-52 and the rocket booster fired
as planned. An anomaly occurred approximately half way through boost. The anomaly
could not be cleared prior to separation. The vehicle could not maintain control and was
lost. Program officials continue to evaluate the flight data from that test to determine
what occurred to cause the fault.
One of the four X-51A test vehicles remains. It has not been decided when or if that
vehicle will fly.
Miscellaneous:
The X-51A is setting the foundation for several hypersonic applications, including
access to space, advanced defense systems and accelerated commercial flight. At
Mach 5, the vehicle is traveling at about a mile a second. At that speed, a flight from
New York to Los Angeles could take less than 39 minutes.
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Contact:
Cheryl Sampson
Phantom Works
Office: 714-934-9373
Mobile: 714-330-8021
cheryl.a.sampson@boeing.com
Deborah VanNierop
Phantom Works
Office: 314-232-1624
Mobile: 210-454-2656
deborah.a.vannierop@boeing.com
September 2012