December 12, 2009 - The X-51A Waverider was carried aloft for the first time December 9, 2009, by an Air Force Flight Test Center B-52 Stratofortress over Edwards Air Force Base, Calif. The test was a key milestone in preparation for the X-51 to light its supersonic combustion ramjet engine and propel the WaverRider at hypersonic speed for about five minutes, before plunging into the Pacific Ocean.  

"This was a great day for the program," said Charlie Brink, X-51A program manager with the Air Force Research Laboratory at Wright-Patterson AFB, Ohio. "The early look is we successfully captured all of our test points without any anomalies. I'm really proud of the AFRL, Air Force Flight Test Center, and Boeing/Pratt Whitney Rocketdyne teams' efforts to move us toward the big event. That flight test is currently planned in about two months, he said.  

The Dec. 9 test, reminiscent of the early days of the historic X-15 program 50 years earlier, was conducted entirely in the airspace over Edwards AFB while various systems and telemetry were checked out. The Flight duration was 1.4 hours.

"After takeoff we climbed to 50,000 feet and verified B-52 aircraft performance, handling qualities with the X-51A attached to the B-52, control room displays and software integration with the X-51A," said Lt. Col. Daniel Millman, a B-52 project pilot. "The B-52 handled great and the flight preceded as planned." 

The next B-52/X-51 flight test mission is expected in mid-January, and will be a full dress rehearsal, for its first hypersonic test flight, now planned for mid-February, Mr. Brink said. The dress rehearsal flight will depart Edwards AFB and head out over the Pacific to Point Mugu Naval Air Warfare Center Sea Range. Both airborne and multiple ground test assets will monitor all X-51A systems, but it will not be released from the B-52 and its engine will not ignite.  

In February, the Air Force Flight Test Center's B-52 will carry the unmanned X-51A to approximately 50,000 feet over the Pacific Ocean then release it. A solid rocket booster from an Army Tactical Missile System will then ignite and accelerate the X-51 to about Mach 4.5. Then the booster will be jettisoned and the X-51A's supersonic combustion ramjet propulsion system will ignite and operate for about 300 seconds, propelling the cruiser to more than six times the speed of sound. Onboard sensors will transmit data to ground systems before the cruiser plunges into the Pacific. There are no plans to recover it. 

Four X-51A cruisers have been built and were developed by officials from the Air Force, Defense Advanced Research Projects Agency, Pratt & Whitney Rocketdyne and Boeing. Pratt & Whitney Rocketdyne built the X-51's scramjet engine, which is the heart of the system. Engineers expect a great deal will be learned about hypersonic flight during the nearly 300 seconds under scramjet power. The longest-ever previous scramjet test, lasted only about 10 seconds, Mr. Brink said.  

As the engine ignites it will initially burn a mix of ethylene and JP-7 fuel before switching exclusively to JP-7. The X-51's fuel-cooled engine design will both heat the JP-7 to an optimum combustion temperature and help the engine itself endure extremely high operating temperatures during the long burn. "We believe the X-51 will lead the path to practical air breathing hypersonic flight," said George Thum, Pratt & Whitney Rocketdyne X-51A program manager.