The top US Air Force (USAF) officer says his service aims to reach a decision on the future powertrain of Lockheed Martin’s F-35 Joint Strike Fighter by the end of the year.
General Charles Brown was speaking at the Air & Space Forces Association (AFA) Annual Conference on Sept. 20 near Washington, DC.
“We want to make a decision later this year,” Brown says.
The question is whether the USAF’s F-35As will get an all-new engine, or whether the service will upgrade the type’s existing Pratt & Whitney F135 engines.
Equipped with an increasingly capable array of onboard sensors, the advanced fifth-generation aircraft has surpassed the power generation and cooling envelopes of its original engine. According to P&W, F135s are capable of meeting current requirements but will require more frequent maintenance.
In 2016, the USAF gave P&W and GE Aviation $1 billion each to develop competing new engines for F-35s under an initiative called the Adaptive Engine Transition Program (AETP). So-called adaptive engines can adjust internal airflow to provide the high performance of a conventional fighter jet and the cruise efficiency of an airliner.
GE said it completed final testing of its AETP prototype, the XA100, earlier this month.
P&W’s is developing its XA101 for the program. But it also offers an alternative option – an F135 upgrade called the Enhanced Engine Package (EEP).
The company says the EEP core upgrade is a significantly cheaper and faster option to address the performance and cooling issues without requiring a full motor swap.
While the USAF has shown interest in the increased thrust and acceleration that AETP engines offer, service leaders have also expressed cost concerns.
The US Navy and US Marine Corps, which operate the F-35C and F-35B variants, have expressed little interest in purchasing a new engine, meaning the USAF could be on the hook for the entire cost of the program.
In his speech at the AFA event, Brown refuses to say which direction the USAF is headed. He says the USAF is working with other services and the Department of Defense to find a solution.
“We want to examine all options,” he says.
The USAF recently awarded nearly $5 billion in contracts to five defense contractors, including GE and P&W, to develop adaptive engines for its Next Generation Adaptive Propulsion program, which will provide an engine for a proposed sixth-generation fighter aircraft .
