- Press Release
- August 16, 2022
World’s First Flight-Weight, Hydrocarbon-Fueled Scramjet Completes Mach 4.5 Testing, Running at Mach 6.5
Pratt & Whitney (P&W) announces the completion of 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-
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
“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.
P&W Space Propulsion, a leader in liquid, solid and hypersonic propulsion,
has sites located at West Palm Beach, Fla. and San Jose, Calif., United
States. P&W’s web site address is www.pratt-whitney.com . P&W, a United
Technologies company, is a world leader in the design, manufacture
and service of aircraft engines, space propulsion systems and industrial gas