Aviation system manufacturer Honeywell says it can deliver significant improvements to onboard power generation for the Lockheed Martin F-35 stealth fighter, even without installing new hardware on the complex jets.
Honeywell is positioning itself as the low-risk choice for a much-anticipated Pentagon programme to upgrade the F-35’s power and thermal management system (PTMS), which provides electrical power to critical aircraft systems and serves as the jet’s auxiliary power unit.
The PTMS also cools down the F-35’s sensors and communications systems, which have grown increasingly powerful over successive F-35 upgrades, generating additional waste heat.
The result is a deficit of onboard cooling capacity that overtaxes the single Pratt & Whitney (P&W) F135 engine, requiring more frequent overhauls and driving up sustainment costs.
Honeywell tells FlightGlobal it can deliver a 25% improvement in performance over the existing PTMS via a software update, without the need to replace or modify any of the complex system’s physical machinery.
“We’ve been investing internally to posture for some of that growth potential and needs for the platform,” says Tony Rich, Honeywell’s director of technical sales.
The Pentagon has not yet released specific technical requirements for a PTMS upgrade. For now, the F-35 Joint Program Office (JPO) is focusing on improving the power generation capacity of the F135 turbofan, contracting with P&W to perform an engine core upgrade.
However, a 2023 report from the US Government Accountability Office found the F-35 will need a separate PTMS upgrade by 2029, both to support planned capability improvements for the jet and to reduce sustainment costs associated with the current deficit.
Rich says software changes can get the current PTMS up to an output of 40kW – a level generally identified as necessary to support the planned set of upgrades to the F-35’s weapons, sensors and communications collectively known as Block 4.
Beyond the 2029 timeframe, Rich says Honeywell is looking at delivering 80kW of power generation with some hardware changes to the existing PTMS.
“We believe it’s going to be about a 95% hardware similarity to what we have now, as well as 80% software similarity,” he says. “So, not a lot of changes required there to get us that 80kW growth path.”
Honeywell is using a digital engineering simulation to develop and test various improvement options while the company waits for a formal set of requirements from the Pentagon.
Competing against Honeywell is RTX subsidiary Collins Aerospace, which is proposing a wholesale replacement for the PTMS called the Enhanced Power and Cooling System (EPACS).
Collins has promised the EPACS will deliver 80kW with a drop-in solution that does not require any physical modifications to the F-35 aerostructure and will be compatible with all three variants of the jet.
In February, Collins tested a fully-functional EPACS demonstrator the company claimed was at a technology readiness equivalent to that required at the early engineering and manufacturing development phase of new procurement programmes.
“We stand ready to begin the integration process with Lockheed Martin and help service members meet their urgent mission requirements,” said Henry Brooks, president of power and controls for Collins.
The competition between an entirely new hardware package and an upgrade to the existing system has echoes of the earlier contest between P&W and GE Aerospace to deliver a propulsion enhancement for the F-35.
In that long-running saga, GE pushed for the US Air Force to field an entirely new adaptive cycle turbofan engine; P&W argued that a core upgrade to the existing powerplant represented a faster and more affordable option to solving the onboard power deficit.
Opposition from the US Navy and Marine Corps to fielding a new engine, which would not have been compatible with the short take-off and vertical landing F-35B fleet, ultimately pushed the Pentagon to select the core upgrade option.
Honeywell has taken note of that outcome and is pursuing a similar rhetorical strategy in selling a PTMS upgrade over a full replacement like the EPACS.
Rich argues that tweaking the existing system will be a significantly cheaper and faster option, requiring less retraining of maintenance personnel and fewer changes to the existing F-35 supply chain and sustainment enterprise.
“We think it’s over about $7 billion worth of cost savings for the life cycle of the system,” he says, comparing a PTMS upgrade to replacing the system with a clean-sheet design.
Honeywell also estimates its PTMS upgrade can be accomplished in as little as one week of work per individual aircraft, even with hardware changes. By contrast, the company claims installing and testing a full replacement would take something like seven weeks per aircraft.
It remains unclear when the Pentagon will issue a formal set of requirements for a power and thermal enhancement programme, officially launching a competition. The JPO and Lockheed have lately been consumed with certificating the much delayed Technical Refresh 3 (TR-3) package of hardware and software meant to enable the subsequent Block 4 improvements.
In the meantime, Both Collins and Honeywell are continuing to mature their prospective offerings for increasing onboard power and cooling with internal research and development funds.
“We’ll support the requirements as they come,” says Rich. “We understand the system, understand the platform and understand the potential needs that are out there.”
While those requirements are still up in the air, Lockheed and the US government are suggesting potentially radical upgrades to F-35 capabilities in the coming decades.
Lockheed chief executive James Taiclet in April said he has challenged Lockheed’s engineers to develop improvements that can “supercharge” the F-35 to a “fifth-generation-plus concept” for operations well into the latter half of the century.
Separately, US President Donald Trump suggested Washington would pursue what he called a “simple upgrade” effort to incorporate a second engine to the F-35, a configuration Trump dubbed the “F-55”.
Such an addition would require a near complete redesign of the fighter, likely taking years and billions of dollars to accomplish.
