The U.S. Air Force awarded contracts of nearly $1 billion each to GE Aviation and Pratt & Whitney to further develop a next-generation military jet engine under the Adaptive Engine Transition Program (AETP). The service envisions the new engine powering a sixth-generation fighter and potentially an upgraded F-35 Lightning II.

In dual contract announcements on June 30, the Department of Defense (DOD) said GE Aviation was awarded $919.5 million and Pratt & Whitney $873 million to design, build and test “multiple complete, flight-weight centerline, 45,000-pounds thrust turbofan adaptive engines.” The contracts, overseen by the Air Force Life Cycle Management Center at Wright Patterson Air Force Base, Ohio, call for completing work by Sept. 30, 2021. When including a priced option, both contracts exceed $1 billion.

Current, fixed-cycle engines powering military jets are optimized for either maximum power or fuel efficiency. GE said its three-stream adaptive cycle AETP engine can transition from a high-bypass, fuel efficient engine similar to engines used on tankers and transports to a low-bypass, high-performance engine required for fighters. In addition to the adaptive feature, a “third stream” of airflow can be used to improve fuel efficiency or further increase thrust.

The AETP program evolved from the Air Force Research Laboratory’s (AFRL) Adaptive Versatile Engine Technology effort begun in 2007 and involving engine manufacturers GE Aviation and Rolls-Royce North America, to the follow-on Adaptive Engine Technology Development (AETD) program awarded to GE Aviation and Pratt & Whitney in 2012.

GE laid claim to testing the first full adaptive-cycle, three-stream engine in 2014, and it completed an AETD preliminary design review in March 2015. The manufacturer said its engine design extends aircraft operating range by more than 30 percent, improves fuel consumption by 25 percent and increases thrust by more than 10 percent.

“For nearly a decade, GE Aviation has successfully partnered with the DOD to effectively design, manufacture and test our revolutionary combination of engine architecture, compression technology, cooling technology and material technology advancements,” said Dan McCormick, GE Aviation general manager of advanced combat engine programs. “We are honored to continue our work with AFRL while initiating the next phase of the technology maturation.”

Pratt & Whitney, which supplies the F119-PW-100 turbofan engines on the F-22 Raptor, the F135 engine of the Lightning II and the unannounced engine of the future B-21 long-range strike bomber, demonstrated a three-stream fan in a test rig in 2013 under the AETD program. It has also participated in the Navy’s Variable Cycle Advanced Technology program to develop new propulsion technology for next-generation F/A-XX and carrier-based aircraft.

“We've gained tremendous insight from our experience designing engines for the F-22 and the F-35, which are truly a generation ahead,” said Jimmy Kenyon, Pratt & Whitney senior director of advanced programs and technology. “With that foundation in place, along with the tremendous progress we've made to date on AETD with our Air Force teammates, we're eager to move into the next phase of adaptive engine development.”