F-35A
LE BOURGET—The F-35 will require 20%-30% more cooling for a future Block 5 upgrade beyond Block 4, and Lockheed Martin wants to pursue optimal power and cooling increases for the jet despite a U.S. Air Force plan to not re-engine the aircraft.
The need for more cooling has emerged as a top priority for the F-35 program, with the current system overstressed and leading to potentially $38 billion in increased maintenance for the U.S. fleet. The F-35 Joint Program Office is expected to decide a final cooling requirement for upgrades, and Lockheed Martin wants to pursue as much of an increase as possible—including a new Power and Thermal Management System (PTMS) and approving the full re-engining that the U.S. Air Force has proposed ending.
“I want it all, in simple terms,” said Greg Ulmer, Lockheed Martin’s vice president of aeronautics, speaking June 21 in Lockheed Martin's chalet here at the Paris Air Show. “And I think people are kind of positioning, companies are positioning for solution sets that aren’t quite defined yet. So, let’s understand what the requirements are then let’s go get as much margin as we can."
“I’m more open to not narrowing down on specific solutions yet," he continued. "We have enough runway to get to that, probably in the next two to three years, and then we need to start making some hard decisions.”
The F-35 Joint Program Office is set to meet in September to define the cooling requirements for all aircraft operators. This after a report from the Government Accountability Office in May said that the program has not determined the power and cooling requirements beyond 2035.
At the show on June 19, Collins Aerospace announced that lab tests showed its proposed Enhanced Power and Cooling System (EPACS) could provide more than 2 1/2-times the cooling power of the current system. Collins says it will achieve Technology Readiness Level 6 this year and would be ready to become an Engineering and Manufacturing Development program as early as 2024.
But Ulmer said a specific program like this is premature until the needs are fully understood.
“I’m not going to stand behind any one solution or engine provider,” he said. “I’m going to stand for: Here’s what the airplane needs from a demand perspective and margin, and it’ll be informed by the Block 5 requirements as they’re defined.”
Ulmer said he is an “advocate” for adopting a powerplant developed as part of the Air Force’s Adaptive Engine Transition Program (AETP)—the GE Aerospace XA100 or Pratt & Whitney XA101. The U.S. Air Force, in its fiscal 2024 budget request, proposes canceling AETP and instead opting for Pratt’s F135 Engine Core Upgrade program. Service Secretary Frank Kendall says he would like an AETP solution, but it would be cost prohibitive at a price tag of several billion dollars. The F-35A-operating Air Force is the only one that is interested in the engines, he says.
Pratt & Whitney argues that its F135 ECU is the only potential upgrade that would fit in all variants of the F-35, a point that has been contested. Ulmer said an AETP engine could fit in A and C variants, though integration into the F-35B short-takeoff-and-vertical-landing (STOVL) variant would require extensive work.
“That’s the concern, the STOVL,” he said. “How you could get around that is, it’d be new physics. You’d have to change some of the structure of the airplane, etc. There’s just size constraint relative to the increases.”
Despite potential variance in F-35s between international operators, with different needs and budgets for upgrades, Ulmer said all should at least have the option for cooling and power upgrades.
“If you think about the Group A capability inherent in the airframe, I’d rather have that offering,” Ulmer said. “It will be a function of economics, it’ll be a function of customer requirements, what they decide to do as a customer. But I would like to offer them the choice.”
Lockheed Martin is in the middle of flight testing the Tech Refresh 3 upgrade, required for the upcoming Block 4. This includes a new integrated core processor, new panoramic cockpit display, a new memory unit and a new digital aperture system. At the company’s Fort Worth assembly plant, jets are being built with TR3. However, the Joint Program Office announced this month it is not accepting deliveries of these jets until they are certified.
Jets will be ready for delivery starting next month, with flight tests completed in the fall. Ulmer said he expects certification by year's end. This will create a backlog of aircraft in Texas, but it would not be the first time. In December, Lockheed Martin halted deliveries for three months after a crash at the site. After flights and deliveries resumed in March, the backlog was cleared earlier this month. The TR3-related backlog will likely be similar, Ulmer said.
For international customers, Lockheed expects short-term interest from Greece and the Czech Republic for new orders. Ulmer says existing operators are also expected to increase their fleets, including Australia, Israel and South Korea.
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