Development of revolutionary engines at GE Aviation is setting the stage for the next 50 years in military aircraft propulsion, engineers there believe. Just as the turbojet engine gave way to the turbofan half a century ago, so GE’s unique adaptive cycle, three-stream engine architecture could bring fighters of the future both higher performance and longer range with less fuel burn.

The engine can adapt in flight to give maximum thrust or long-range cruise, while a third stream of air will cool both the engine and the aircraft’s systems, explains Jean Lydon-Rodgers, vice president and general manager of GE Aviation’s military systems.

GE Aviation finished running a proof-of-concept engine last year under the U.S. Air Force-backed Adaptive Versatile Engine Technology (ADVENT) program, and is now wrapping up analysis of what it termed highly successful tests. These included the highest combined compressor and turbine temperature operation “in the history of jet engine propulsion.”

GE’s adaptive cycle engine architecture is unique to the aero engine industry, says Daniel McCormick, general manager of advanced combat engine programs at GE Aviation. It is now being applied to the next step – an engine that could fit an F-35-like aircraft. “This culminated in March in a preliminary design review,” he says, that involved the Air Force, NASA and Lockheed Martin, among others. This program, dubbed Adaptive Engine Technology Development (AETD), will involve three major rigs run through 2016 for the compressor, a fan with adaptive features, and a core engine test, but not for a full-up engine.

GE is now helping shape a follow-on program, the Air Force-backed Adaptive Engine Transition Program (AETP), that would involve multiple full-up engine tests. “If it proceeds we could run multiple engines through 2018-19,” McCormick said.

“The sixth-generation fighter engine is a big piece of the future of the business. That’s why we’re investing heavily in it,” says Lydon-Rodgers.

That investment also involves materials including ceramic matrix composites and titanium aluminides, and techniques such as additive manufacturing, to make the engines lighter and more robust while running hotter and providing more power. The military engines are benefitting from GE’s huge investment in such materials and manufacturing readiness for its next generation of commercial engines, which helps keep the costs down for the warfighter, she says.

While an adaptive cycle, three-stream engine could power next-generation fighters, it could also be seen as a possible retrofit and upgrade for the F-35 Joint Strike Fighter, where it would improve performance and range and remove some of the low altitude/high speed flight restrictions imposed by current issues with thermal management of the aircraft and its systems.

GE is showing a video on how the adaptive cycle works here on its stand (Chalet 142).