Running at Mach 6.5!

Pratt & Whitney (P&W) has completed Mach 4.5 ground testing on the world's first flight-weight, hydrocarbon-fueled, scramjet engine. Ground testing at Mach 6.5 is expected to be completed later this month.  This engine, known as the Ground Demonstration Engine (GDE-1), uses standard JP-7 fuel in an "endothermic/regeneratively cooled cycle" during which the fuel cools the engine's interior walls before being introduced to the combustion chamber to produce trust. The engine injects, mixes and burns fuel to make thrust in a time span of less than 0.001 seconds.

Successful ground testing of GDE-1 represents a significant milestone for P&W Space Propulsion, which is teamed with Air Force researchers under the Hypersonic Technology (HyTech Program). GDE-1 testing followed the team's outstanding results on the Performance Test Engine (PTE), which completed testing in 2001.

"GDE-1 testing is a huge step toward flight-testing, which is an essential next step to the evolution of this technology," P&W Space Propulsion & Russian Operations President Larry Knauer said. "We are on track for this program to change the aerospace industry forever, as this technology will create a paradigm shift in the way we employ propulsion for access-to-space and global- reach applications."

The GDE-1 engine, which weighs less than 150 pounds, produced net positive thrust during 45 runs at Mach 4.5 and 12 runs at Mach 6.5 between September 2002 and June 2003.

"The initial phase of this program is intended to evaluate engine operation and structural/thermal margins at Mach 4.5 and 6.5," Knauer said. "Engine testing is proceeding as planned, and the simulation and resultant engine performance is comparable to or better than our previous PTE. Our fuel- cooling flow rates are matched to combustor flow requirements and metal temperatures and fuel temperatures match predictions."

The next engine in this successful series of ground demonstration engines will be denoted GDE-2. This engine will also be fuel-cooled and flight-weight like the GDE-1; however, GDE-2 will feature a fully integrated fuel-system that will introduce control hardware and software, allowing the engine to run as a complete closed-loop system. GDE-2 will incorporate a Full Authority Digital Engine Controller (FADEC) to orchestrate complex fuel controls and transitions.

"We expect the first full-up GDE-2 to be testing in '04," Knauer said, "and we have a derivative of GDE-2 scheduled for flight test '06/'07." To develop the GDE design, the Hydrocarbon Scramjet Engine Technology (HySET) team used a building-block approach that began with computational fluid dynamic codes. The world-class hypersonic codes define combustion products while optimizing the fueling locations and concentrations required for top performance. Computational results are used to refine engine lines, allowing optimization of the engine design prior to test. Near-term applications for the HyTech technology include a fast-reaction, long-range air-to-surface missile with a Mach 6.5-plus-cruise capability to fly hundreds of nautical miles in minutes.

Such missiles could be carried on fighter and bomber aircraft in U.S. Air Force inventory and on U.S. Navy aircraft, ships and submarines. The long-term vision for the scramjet engines include power for launch vehicles that can substantially reduce the cost of access to space, along with military and commercial aircraft that can span the globe in less than a few hours.

The U.S. Air Force established the HyTech Program in 1995 to maintain an aggressive technology development program in hypersonics after the National Aero-Space Plane's development was terminated. In 1996, P&W won a $48-million contract for HySET. As a result of the program's success, the X43-C, a joint USAF/NASA program, has emerged. The goal of this program is to flight test a derivative of the HySET engine in 2007.

FMI: http://www.pratt-whitney.com