Raytheon Technologies [RTX] said that it will be able to outfit 24 F-35 squadrons with an Engine Core Upgrade (ECU) for the company’s Pratt & Whitney F135 engine by 2030–seven squadrons in 2029 and 17 in 2030–compared to just two F-35 squadrons that could receive a new engine under the Adaptive Engine Transition Program (AETP) in 2030.
The ECU and Raytheon’s proposed Emergency Power and Cooling System (EPACS), which is to achieve Technology Readiness Level 6 next year, are to provide a seven percent increase in performance range and thrust for the Lockheed Martin [LMT] F-35 fighter, more than twice the cooling of the F135 to accomodate new weapons in F-35 Block 4, and a more than $40 billion savings in life cycle costs.
DoD’s upcoming fiscal 2024 budget may lay out the future engine path for the F-35–whether that be the Pratt & Whitney proposed F135 ECU or a new power plant, such as General Electric‘s [GE] proposed XA100 Tri-Variant Adaptive (TVA) engine (Defense Daily, Oct. 11).
GE said on Dec. 13 that AETP “is the only solution that provides the propulsion capability the F-35 needs in 2028 and beyond to continue to maintain a competitive edge over near-peer adversaries.”
“Through AETP, GE Aerospace has developed an engine with 30 percent more range, 20 percent greater acceleration and double the thermal management capacity – revolutionary new capabilities that can be delivered in quantity by the end of the decade,” per GE Aerospace. “Our XA100 engine is tested and ready, and we are glad to see Congress recognize the importance of continuing to support these capabilities in the current defense bill.”
Raytheon suggested, however, that DoD could not accelerate AETP development and fielding.
“As to why we can’t do XA faster, it has to do with the fact that the ECU is a core upgrade, meaning 70 percent of the material likely will stay common,” Jen Latka, Pratt & Whitney’s vice president for F135 programs, told reporters in a virtual briefing/question and answer session on Dec. 13. “There’s no touching the [engine] fan. We’re not touching the back end of the engine. It [ECU] is limited in scope to the core. We are limiting the technologies that we bring in to what is absolutely necessary.”
“The supply base that we currently have is the supply base that will manufacture ECU,” she said. “They’re already up and established, and there won’t be massive changes…On the other hand, when you look at how historically how long it takes to ramp a brand-new center line engine, let alone one that has never flown before so we’ll have a tremendous amount of learning and we’ll need a very robust flight test program, given it’s only engine on this aircraft, that’s gonna take a lot of time. The test program will take a lot of time, and then standing up the supply chain and the supply base and ramping them to full rate is going to take years.”
Regarding the F135 and the Pratt & Whitney F119 engine for the U.S. Air Force F-22 fighter by Lockheed Martin, “we didn’t get to [a build] rate [of] 150 every year overnight,” Latka said. “It took many years. It [AETP] is a completely new engine with completely new parts to manufacture.”
Raytheon also said that AETP is “significantly heavier” than the F135 and the F135 ECU, which Raytheon said is weight “neutral” compared to the F135, but the company declined to disclose how much heavier the AETP is/will be and referred that question to the F-35 Joint Program Office (JPO).
The F135 for the Air Force F-35A and the U.S. Navy F-135C “is roughly 6,400 lbs.,” the F-35 JPO said on Dec. 14. “The F-35 propulsion system for the F-35B variant is roughly 10,400 lbs. This is because the F-35B has the additional lift system (lift fan, rolls posts, etc.) which weighs roughly 4,000 lbs. Weights related to the Engine Core Upgrade and Adaptive Engine Transition Program are proprietary and not publicly releasable.”
The ECU was formerly known as the Engine Enhancement Program but the F-35 JPO changed the name recently.
Pratt & Whitney recently received a more than $115 million contract for ECU work through May next year (Defense Daily, Dec. 5).
Technology Refresh 3 (TR3)–spurred by the L3Harris [LHX] integrated core processor–is the computer backbone for Block 4, which is to have 88 unique features and to integrate 16 new weapons on the F-35. The F-35 program has said that the fighter will need a new or significantly upgraded engine with improved electrical power and cooling capacity to accommodate the 53 new capabilities slated for F-35 Block 4.
In October, 48 representatives urged DoD to invest in next generation, adaptive propulsion for fighters in a letter co-sponsored by Sens. Rob Portman (R-Ohio) and Sherrod Brown (D-Ohio) and Rep. Brad Wenstrup (R-Ohio).
In all, 13 of 16 Ohio representatives signed the letter.
General Electric’s GE Aviation subsidiary has its headquarters in Evendale, Ohio outside of Cincinnati.
GE has said that it began working with the F-35 JPO in the fall of last year on evaluating whether GE could alter the proposed XA100 for the U.S. Air Force’s AETP to fit on the U.S. Marine Corps F-35B.
Since 2016, the Air Force has funded the AETP.
The F-35 program has said that while the XA100 TVA is based on the F-35A’s F135 engine, the TVA would require an independent development program.