Aviation Week | Brian Everstine
December 13, 2022
Collins Aerospace and Pratt & Whitney have unveiled a new power and cooling system for the proposed upgraded F135 engine core, aiming to increase the power output and cooling required for coming F-35 upgrades as the Pentagon considers the future of the Joint Strike Fighter’s powerplant.
The Raytheon Technologies companies say the Emergency Power and Cooling System (EPACS) with the F135 Engine Core Upgrade (ECU) will bring a 7% increase in range and thrust and twice as much cooling. The system is compatible with all F-35 variants and can reach technology readiness level six in 2023, meaning it is ready for a technology demonstration. The company claims it would provide about 10s of billions in savings compared to replacing the aircraft’s entire engine.
The U.S. Air Force has been considering a full engine replacement for its F-35A fleet, looking at the two powerplants developed in the service’s Adaptive Engine Transition Program (AETP)—the GE Aerospace XA100 and Pratt’s XA101. GE has been publicly pitching its offer and claims it could also work in the short takeoff and vertical landing F-35B variant. Meanwhile, Pratt has focused on pushing the F135 ECU, previously called the enhanced engine package, as a faster and more cost-effective way to increase the aircraft’s power output.
The F-35 Joint Program Office is undergoing a business case analysis of replacing the F135 in the fleet, and Air Force Secretary Frank Kendall has said his service would make its decision in its upcoming fiscal 2024 budget request. He has said he supports an AETP-like solution for the fleet based on efficiency gains, though he wants buy-in from other military services that have not been as publicly open to the idea.
On Dec. 2, Pratt & Whitney received a $115 million contract for the F135 enhancement effort, with the funding to support preliminary development through 2023. If this funding continues, Pratt & Whitney could cut into F-35 production and enter service with the F135 ECU in 2028, delivering to seven F-35 squadrons the following year. The company projects a cost of $2.4 billion for its development, compared to $6.7 billion for the AETP replacements, with the latter not entering service until 2030.
The current F135 is under heavy strain supporting the F-35’s advanced avionics and issues with thermal management. The Joint Program Office says the Block 3 version of the F-35 produces 30 kW of waste heat from electronics, with that number to grow to 47 kW in Block 4. The current engine is optimized to absorb up to 14 kW of waste heat. Pratt says the current engine can provide the needed power, but it will burn hotter, requiring more maintenance.
“Really what the customer is looking for is more cooling to power these weapons systems … Pratt & Whitney is offering the Engine Core Upgrade because it solves the problem and it does so in the most cost-effective way,” says Jen Latka, vice president of F135 systems at Pratt & Whitney.
The new EPACS is a Collins-designed system, with an air cycle machine and power generation connected to Pratt’s auxiliary power unit. Kim Kinsley, vice president of environmental and airframe control systems at Collins, says it is built of existing technologies used in both commercial single-aisle and wide-body aircraft, along with military fixed-wing and rotary-wing aircraft.
“It’s a pretty wide platform diversity that we’re able to pull from and really help to ensure that we’ve got the right product technology base, which we can mature off of,” she says.