The Air Force said Aug. 5 that it recently set a record for the highest thrust produced by an air-breathing hypersonic engine in service history during a nine-month testing period.

The Air Force Research Laboratory (AFRL) and Air Force Test Center achieved over 13,000 pounds of thrust from an 18-foot-long Northrop Grumman [NOC]-built scramjet engine during tests at Arnold Air Force Base, Tennessee. The engine successfully lasted for 30 minutes-worth of accumulated combustion time over those nine test months.

Hypersonic vehicles operate at extreme speeds and high altitudes. Northrop Grumman and Raytheon are teaming to accelerate air-breathing hypersonic vehicle development. (Image: Northrop Grumman)

“After years of hard work, performing analysis and getting hardware ready, it was a great sense of fulfillment completing the first successful test of the world’s largest hydrocarbon fueled scramjet,” said Todd Barhorst, AFRL aerospace engineer and lead for the Medium Scale Critical Components program, in a Monday press release.

Pat Nolan, Northrop Grumman’s vice president for missile products, said in the statement that “The scramjet successfully ran across a range of hypersonic Mach numbers for unprecedented run times, demonstrating that our technology is leading the way in delivering large scale hypersonic platforms to our warfighters.”

The Air Force has been hard at work to produce a “larger and faster” hypersonic air-breathing engine over the past decade, since the service conducted several hypersonic test flights with the X-51 Waverider, Barhost said.

The X-51 was an unmanned scramjet aircraft jointly developed by government entities including AFRL, NASA and the Defense Advanced Research Projects Agency (DARPA), along with industry partners Boeing [BA], Pratt & Whitney [UTX] and Whitney Rocketdyne, now Aerojet Rocketdyne [AJRD].

“A new engine with 10 times the flow of the X-51 would allow for a new class of scramjet vehicles,” Barhost said.

The AEDC Aerodynamic and Propulsion Test Unit at Arnold Air Force Base supports recent testing for the Air Force Research Laboratory Medium Scale Critical Components Scramjet program. The Northrop Grumman-produced engine was successfully operated at conditions above Mach 4 and has set the record for highest thrust produced by an air-breathing hypersonic engine in Air Force history. (U.S. Air Force photo)

The Air Force and DARPA are partners on the Hypersonic Air-Breathing Weapon Concept (HAWC) program that could eventually become an air-launched hypersonic cruise missile. Northrop Grumman and Raytheon [RTN] announced in June a signed teaming agreement to develop, build and integrate Northrop Grumman’s scramjet combustors aboard Raytheon’s weapon system under a $200 million contract for the HAWC program.

The Air Force funded a two-year upgrade to the Arnold Engineering Development Complex to enable large-scale scramjet combuster tests, such as the most recent success, the release said. In April, then-Air Force Secretary Heather Wilson shared with Congress that the service would be building an additional large-scale wind tunnel at Arnold, as well as new “quiet” wind tunnels designed to minimize freestream disturbances at Purdue University and the University of Notre Dame, both in Indiana (Defense Daily, April 18).