Adaptive Engine Transition Program (AETP)| A revolutionary propulsion mechanism for the F-35

A new type of jet engine is being developed, according to a public announcement made by the Air Force Research Laboratory (AFRL) on March 26, 2007, that will now “allow pilots to go from high-speed combat maneuvers to long-range persistence mode as smoothly as a bird in flight.”

The program in effect was called Adaptive Versatile Engine Technology, or ADVENT, and its primary objective was to develop the combat aircraft engines of the future. ADVENT would aim to create the technology required for a ground-breaking three-stream adaptive cycle engine, in contrast to the fixed, two-stream turbofan engines that had powered (and now power) the Air Force’s fighter fleets since the 1970s.

Representative | GE Aviation

The milestone was achieved on March 25 at Arnold Engineering Development Complex in Tennessee, which was a joint venture between GE and the Air Force, using GE’s XA100 engine.

The Adaptive Engine Transition Program (AETP) was launched in 2016 with the intention of creating adaptable engines for sixth-generation fighter propulsion as well as prospective F-35 reengineering using the F135 turbofan engine currently in use. The P&W engine was named XA101, and the General Electric demonstrator was given the designation XA100.

A new era of combat propulsion

The GE XA100 Adaptive Cycle Engine

The XA100 offers a step-change in propulsion that maximizes the F-35A and F-35C’s capabilities for decades to come. It was developed, manufactured, and tested as part of the U.S. Air Force’s Adaptive Engine Transition Program (AETP).

Fuel savings

Lower fuel costs and a lesser reliance on tankers are made possible by three-stream, flexible design thereby enhancing the overall fuel consumption by 25%.

Increased thrust

Provides fighter pilots with more of what they require and at the time of necessity- increased overall thrust by 10%

Enhanced heat absorption

Results in better heat absorption facilitated by additive 3D-printed heat exchangers

Increased range and acceleration

Allows for a 30% increase in range and allow pilots more nimble tactics and aggressive pursuit during aerial combat

Next-generation mission systems

The third stream of this engine will significantly improve thermal management as new mission systems are added to the F-35, enabling mission systems growth for decades to come.

Aircraft benefits

Compatibility with over 90% of the F-35 program of record is made possible by the unique design that allows it to fit both the F-35A and F-35C without requiring structural alterations to either airframe.

The Pratt & Whitney XA101

XA101 adaptive fan being tested at Arnold Engineering Development Complex (AEDC) | Wikipedia

The Pratt & Whitney XA101 is an American adaptive cycle engine demonstrator that is being developed by Pratt & Whitney for the Lockheed Martin F-35 Lightning II and will serve as the foundation for the propulsion system for the sixth generation fighter program of the United States Air Force, known as Next Generation Air Dominance (NGAD).

The Adaptive Versatile Engine Technology (ADVENT) program, a subset of the wider Versatile Affordable Advanced Turbine Engines (VAATE) program, marked the start of the U.S. Air Force and U.S. Navy’s pursuit of the adaptive cycle engine idea in 2007.

Design and specs

The XA101 is a three-stream adaptive cycle engine that, depending on the situation, can change the bypass ratio and fan pressure to increase fuel efficiency or thrust. In order to improve fuel efficiency and serve as a heat sink for cooling, it accomplishes this by utilizing a third bypass stream around the entire engine, with the capacity to control the part of airflow into the engine core or through this third stream. With this feature, the high-speed, low-altitude component of the F-35 flight regime can be used more frequently.

Future use of directed-energy weaponry is also made possible by increased cooling and power generation. The air from the third stream can be diverted into the core and fan streams for improved performance when more thrust is required.

TypeThree-stream adaptive cycle engine
Maximum Thrust45,000 lbf (200 kN) class (with afterburner)

The Air Force’s test cell will conduct more testing in the upcoming months as they attempt to collect performance information across the flying envelope- according to reports.