This year, General Electric [GE] plans to deliver a report to the F-35 Joint Program Office (JPO) on how the company could adapt its XA100 engine for the U.S. Marine Corps F-35B and the cost of such an adaptation.
The Pentagon’s fiscal 2024 budget may lay out a future path for engines for the Lockheed Martin [LMT] F-35–a course of action that may upgrade the existing Pratt & Whitney [RTX] F135 engines or replace them with more fuel efficient and durable ones that would give the fighter more range and weapons carriage. The F-35 JPO has said that the fighter will require better engine capabilities to carry 16 additional weapons envisioned in the aircraft’s Block 4 upgrade, which includes 88 features. The program has said that the F-35 will need such improved engine capabilities after DoD fields the third increment of Block 4.
Since 2016, the Air Force has funded the Advanced Engine Transition Program (AETP), but thus far it appears that an AETP engine will fit on the F-35A and possibly the Navy F-35C, not on the Marine Corps’ F-35B short takeoff and vertical landing variant, as the latter requires an engine that drives the lift-fan system, provides bleed air to the roll-posts, and uses a swivel exhaust duct.
GE said that it began working with the F-35 JPO in the fall of last year on evaluating whether GE could alter the XA100 to fit on the F-35B. GE said that it plans to submit an interim report to the F-35 JPO before September’s meeting of the JSF Executive Steering Board (JESB) and that the company is to submit a final report by the end of the year.
The lift fan, the bleed air for the roll posts, and the swivel exhaust duct “are the unique F-35B engine requirements we’re addressing with the study, while still maintaining as much commonality as possible with the XA100,” GE said.
Pratt & Whitney has participated in AETP with the company’s XA101 engine. The company said it has also been investing internal funds in an Enhanced Engine Package for the company’s F135 engine for all three F-35 variants–a package that Pratt & Whitney said could save tens of billions of dollars in engine life cycle costs and provide the cooling needed for advanced weapons on the fighter by 2027-28 (Defense Daily, Nov. 8, 2021).
In June, 2016, Pratt & Whitney and GE each received contracts worth more than $1 billion each for AETP.
It appears that Pratt & Whitney is looking at how it could adapt the XA101 for the F-35B, but the company referred questions on the matter to the F-35 JPO, which had not responded by press time on June 23.
Launched in 2016, AETP followed Air Force engine developments in the Adaptive Versatile Engine Technology (ADVENT) program, begun in 2007, and the Adaptive Engine Technology Development (AETD) program, started in 2012.
Last month, Air Force Secretary Frank Kendall told the Senate Armed Services Committee that “there are a number of options to improve the performance of the F-35 engine” and that AETP thus far appears to feature “the most impressive technology” in terms of fuel efficiency, range extension and other factors (Defense Daily, May 17). Kendall said that DoD will have to make a decision on the future of F-35 engine modernization.
The Air Force has said that development of AETP may cost $6 billion, but service officials have also said that F135 sustainment has been a significant problem and has decreased F-35 mission capable rates.
The Fiscal 2022 Consolidated Appropriations Act funded AETP at $473 million–$460 million more than the Air Force requested.
The Air Force had requested just $13.5 million in fiscal 2022 for AETP, down from more than $214 million appropriated by Congress in fiscal 2021 and nearly $527 million in fiscal 2020.
The Air Force has said that its focus for AETP has been on the Next Generation Air Dominance (NGAD) fighter, not the F-35A, due to what the service has said are significant costs for retrofitting AETP engines on the F-35A.
In fiscal 2018, the Air Force exercised options in the AETP contract for the Next Generation Adaptive Propulsion (NGAP) risk reduction effort for NGAD engine components. The Air Force said in its fiscal 2023 budget request that the service had broken out NGAP to reveal funding levels. In fiscal 2023, the Air Force requests nearly $68 million for NGAP and about $286 million for AETP.
Congress funded NGAP at nearly $343 million in fiscal 2021 and $110 million in fiscal 2022.