Future F-35 cooling needs unknown as DoD eyes engine upgrade

WASHINGTON — The F-35 program only knows how much cooling the Joint Strike Fighter’s engine will need through 2035, government auditors said in a brand new report.

But that’s just a few years after the F-35 program needs to complete upgrading its thermal management system to have the opportunity to support rapidly arriving recent capabilities, the Government Accountability Office said in a Tuesday report.

And GAO said it’s hard to predict how long the planned upgrades to the F-35′s power and thermal management system, or PTMS, and engines can be effective, though the fifth-generation fighter is anticipated to fly for one more 50 years. PTMS uses the “bleed air” from the engines to chill systems throughout the fighter including weapons and radars.

The finding spotlights the uncertainty this system faces because it prepares for a serious upgrade to the Pratt & Whitney-made F135 engines, dubbed the Engine Core Upgrade. Just just a few years after completing the trouble, the F-35 program “will face a period of unknown requirements” for its future capabilities — and will be at risk of future cost overruns and other mistakes, in response to the brand new report.

“Without defined PTMS and engine modernization requirements, the F-35 program is at greater risk of repeating prior missteps,” GAO said. “By proceeding with planning and development of future capabilities without considering the demands on the PTMS and engine, this system endorsed capabilities that neither could support. This system risks repeating an analogous mismatch between PTMS and engine capability and future modernization needs if the military services select an option without first defining future requirements.”

GAO said the F-35 program can’t fully predict how much power and cooling the fighter will need until the military services flying the aircraft define their very own requirements.

But already, recent capabilities being added to the F-35 are stretching its cooling capabilities beyond their original design, causing the engines to wear down faster. An upgrade program referred to as Block 4 — a $16.5 billion project so as to add recent sensors, more advanced weapons, and more powerful data fusion and advanced electronic warfare — will further tax the engines’ cooling capabilities.

Without an engine upgrade, GAO said, the added heat could drive up the fee of maintaining the present engines by $38 billion.

In a press release to Defense News, the F-35 Joint Program Office said it’s confident the ECU engine upgrades can “minimize” the $38 billion in costs GAO highlighted.

“The ECU will restore engine life, and the [power thermal management system improvements] will be certain that the air vehicle can support future capability growth,” JPO spokesman Russ Goemaere said in an email.

GAO really useful the Pentagon order the JPO, before moving forward with the engine modernization effort, to re-evaluate its evaluation of the right way to upgrade the F-35′s engines after the services spell out what power and cooling capabilities they are going to need.

The Pentagon disagreed with that advice, saying the F-35 program will re-evaluate its evaluation when obligatory because the services’ requirements are updated.

The JPO didn’t reply to an inquiry about whether it knows what the F-35′s post-2035 requirements can be and whether Pratt’s planned engine upgrade will provide enough power and cooling to satisfy those needs.

Goemaere said the JPO is within the early design stages because it weighs several options for improving the fighters’ thermal management systems, which can happen alongside the F135′s core upgrades.

The upgrades to the engines’ core and thermal management system are expected to be fielded within the early 2030s, he said, though the precise schedule will depend upon what design is ultimately approved.

Nonetheless, meaning the engine upgrades obligatory to handle the added heat may come just a few years later than the F-35 will receive its Block 4 upgrades, now projected to be finished in 2029.

More engine cooling — but will it’s enough?

In a briefing with reporters Wednesday, Jen Latka, Pratt & Whitney’s vp of F135 programs, said the present engines would have the opportunity to handle the Block 4 upgrades, albeit at an increased maintenance cost. An upgrade to the engine’s core alone would let the F135 more fully enable Block 4, she said. And an upgrade to the facility thermal management systems would allow the F-35 to handle future upgrades beyond Block 4, Latka said.

She said the engine core and thermal system upgrades together “provides an amazing amount of cooling margin” — good enough to comfortably allow future F-35 capability upgrades beyond 2035, without further improvements to the engine.

“If we’re back here talking a few potential engine upgrade in one other 15 years, my guess is it’s for a special reason,” Latka said. “The quantity of cooling that can be feasible with the ECU and the upgraded [thermal] system … there’s an amazing amount of design margin there.”

The Defense Department considered two principal options for upgrading the F-35′s engines — Pratt & Whitney’s upgrade to the present engines, and a General Electric Aerospace-made engine it dubbed the XA100 that uses an adaptive design. The so-called adaptive engine uses three streams of air, as a substitute of two, to chill the engine and the aircraft, and might adjust to the configuration that may give the plane probably the most thrust and efficiency within the moment.

But in the course of the 2024 budget rollout in March, the Pentagon said it decided to upgrade Pratt’s engines as a substitute of going with a brand new design under the Adaptive Engine Transition Program, or AETP.

Air Force Secretary Frank Kendall said on the time that while GE’s adaptive engine would supply more thrust and cooling capability, it was only certain to slot in his service’s F-35A variants. This meant the opposite services weren’t desirous about an AETP engine, and the fee was too high for the Air Force to bear by itself, Kendall said.

GAO said within the report the Navy’s carrier-based F-35Cs would also have the opportunity to make use of an AETP engine.

But GAO said AETP engines wouldn’t fit within the Marine Corps’ F-35B, which has a novel vertical take-off capability, with no major redesign that may drive up costs and sacrifice commonality across all three variants.

Within the roundtable with reporters, Latka said the GAO report supported the corporate’s position that an F135 upgrade was one of the best option for upgrading all three fighter variants’ propulsion systems at one of the best cost.

But in an email, GE spokesman Adam Kostecki said the report shows how vital it’s for the Pentagon to anticipate what the F-35 will need in the long run and begin investing in technology to satisfy those requirements. The XA100 would have the opportunity to offer considerably greater range, acceleration and cooling capability, he said, and GE urged Congress to support its engine — effectively overruling the Pentagon’s decision — as lawmakers proceed to craft the 2024 budget.