Lockheed Martin to lead $107 million F-35 engine upgrade study
December 17, 2024
In a significant move intended to underpin the capabilities of the F-35 Joint Strike Fighter, the US Department of Defense (DoD) has awarded Lockheed Martin a $107 million contract to evaluate critical upgrades to its Pratt & Whitney F135 engine. The assessment work – aiming to augment existing power and cooling systems – is expected to be completed in December 2026.
“This order provides for research and development efforts for trade studies and alternative assessment of all potential power and thermal management solutions, as well as [the] required engine core upgrade block four integration efforts,” Lockheed Martin clarified. As the F-35 is systematically upgraded with new capabilities, crucial work undertaken by the wide-reaching contract aims to keep the existing engine relevant and able to handle increased electrical power and cooling demands.
Funded by a mixture of US Air Force and Navy research, development, test and evaluation funds (approximately $14.3 million each), around $28.7 million of this will expire at the end of the current fiscal year; highlighting the need for expedited assessment work. A further $6.4 million will be sourced from F-35 cooperative partners.
New research work undertaken by this upgrade study will augment a $1.3 billion contract awarded to the engine manufacturer by the US DoD in October 2024 to continue development work on the engine core upgrade (ECU) programme.
Lockheed Martin’s preferred solution had been an entirely new engine, and two prototype adaptive cycle powerplants were produced by incumbent engine supplier P&W (the XA101) and rival GE Aerospace (the XA100) under the US $4 Billion Adaptive Engine Transition Programme. In 2023, however, the Pentagon deemed the ECU to be the most cost-effective way to address the already identified power and cooling shortcomings.
Speaking in April 2023, secretary of the Air Force Frank Kendall explained: “I support the decision that we did make, which is to go with the ECU, which is an upgrade to the existing engine …. When the department looked at this overall and looked at the alternatives, the right decision for the department was to go with ECU”.
Many believe that this approach was financially driven, but also myopic and inadequate, including Greg Ulmer, Lockheed Martin’s executive vice president of aeronautics. He opined that: “I do advocate, for another engine, [the Adaptive Engine Transition Program, or AETP]. I think some of the approaches today are very short-sighted and not considering a longer-term view. Let’s put as much margin in the airplane as we can today, such that in the future, I don’t have to put another motor in. [So that] I don’t have to bring new power and thermal management cooling into the airplane.”
Without a new engine, there will have to be major changes to the aircraft’s cooling and electrical power systems, with a significant, invasive and costly upgrade to the Honeywell Power and Thermal Management System (PTMS) or a replacement, perhaps in the form of the Collins Aerospace Enhanced Power and Cooling System.
The F-35A’s existing cooling system is already acknowledged to be ‘overloaded’, and the ongoing Block 4 upgrade programme will exacerbate the shortfall in electrical power generation and cooling capacity, requiring more ‘bleed air’ from the engine, and thereby reducing available thrust and engine life and imposing higher repair costs. The cooling system was designed to handle no more than 14 kW of waste heat, but the Block 3F demands 32 kW of cooling capacity, and it has been calculated that Block 4 will require 47 kW. Future upgrades could push the requirement to 62 or even 80 kW.
Additional reporting by Jon Lake
