Pratt & Whitney Rocketdyne, a United Technologies Corp. (NYSE:UTX) company, is a step closer to flight testing the world's first hypersonic hydrocarbon-fueled and -cooled scramjet engine. The X-51A Scramjet Engine Demonstrator-WaveRider (SED-WR) successfully demonstrated key flight clearance objectives in recent ground tests simulating Mach 5 flight conditions.

The X-51A SED-WR program is a collaborative effort of Pratt & Whitney Rocketdyne, the U.S. Air Force Research Laboratory, the Defense Advanced Research Projects Agency (DARPA), NASA and The Boeing Company to demonstrate extended-duration hypersonic flight capability. Ground tests are being conducted at NASA Langley Research Center's 8-foot High Temperature Tunnel in Hampton, Va.

"The exceptional operation of the SJX61-2 flight clearance engine and subsystems allows us to move forward to flight with confidence," said Curtis Berger, hypersonics programs director, Pratt & Whitney Rocketdyne. "Engine performance has met or exceeded our predictions throughout the test series."

"We're extremely pleased with SJX61-2 test results to date," said Charlie Brink, X-51 program manager, Air Force Research Laboratory. "This engine test is the culmination of several years of hard work to mature the X-51's flight propulsion system and from what we've seen so far -- the system is pretty much ready to go. We have a few items that we're fine-tuning to optimize for flight but, for the most part, the engine is operating just the way we want it to."

The X-51 Flight Test Program plans to demonstrate the operation of a scramjet engine within the Mach 4.5 to 6.0-plus range during four flight tests beginning in 2009. The program will set the foundation for several hypersonic applications, including access to space, reconnaissance-strike and global reach.

The SJX61-2 duplicates the flight configuration propulsion design, including a Full Authority Digital Engine Control (FADEC), flight fuel pump and ethylene start system to orchestrate the closed-loop thermal management and combustion systems that use JP-7 fuel.

Ground tests of the SJX61-2 and predecessor engine SJX61-1 have verified thermal and structural capability of the propulsion system in addition to validating the engine's start system, performance and operability across the X-51 flight envelope.

The success of the SJX61-2 is built on Pratt & Whitney Rocketdyne's hypersonic propulsion development work during the Hydrocarbon Scramjet Engine Technology (HySET) Program, under funding from the U.S. Air Force Research Laboratory. The engine's control system shares technology derived from Pratt & Whitney's extensive experience in military engine electronic controls and the company's F119 turbofan powering the U.S. Air Force's F-22 Raptor.

Pratt & Whitney Rocketdyne, Inc., a part of Pratt & Whitney, is a preferred provider of high-value propulsion, power, energy and innovative system solutions used in a wide variety of government and commercial applications, including the main engines for the space shuttle, Atlas and Delta launch vehicles, missile defense systems and advanced hypersonic engines.

Pratt & Whitney is a world leader in the design, manufacture and service of aircraft engines, space propulsion systems and industrial gas turbines. United Technologies, based in Hartford, Conn., is a diversified company providing high technology products and services to the global aerospace and building industries.