The F-35 Lightning II, now considered the world’s dominant fighter with over 1,245 aircraft produced and 19 global customers, faces a critical juncture. To maintain its relevance in future battlespaces, serve as a node for multi-domain operations, and potentially control unmanned collaborative combat aircraft (CCA), the F-35 demands enhanced sensors, weapons, and capabilities, including advanced radar and electronic warfare systems.
The Cooling Bottleneck: A Challenge for Future Upgrades
However, a significant limitation exists: the current F-35 lacks the cooling capacity to power the core processing capabilities desired by the Joint Program Office (JPO) without a power thermal management system (PTMS) upgrade. The JPO is exploring a competitive program to improve the PTMS, currently manufactured by Honeywell for all F-35 aircraft worldwide.
JPO’s Goal: Doubling Cooling Capacity
The JPO’s ambition is to increase the cooling capacity from the current 32 kilowatts to the 62-80 kW range, necessary for post-Block 4 and subsequent upgrades.
Honeywell’s Perspective: An Integrated System at the Core
„The power thermal management unit is an integral system of the F-35 aircraft that basically integrates four major systems on board: auxiliary power unit, emergency control systems, and environmental control and thermal management or cooling capacity requirements for the aircraft itself,” said Jim Currier, President and CEO of Honeywell Aerospace Technologies, in an interview with Breaking Defense. „Within those four integrated systems are 14 major functions that are all commanded and controlled through the PTMS, including the On-Board Inert Gas Generation System (OBIGGS) and On-Board Oxygen Generation System (OBOGS), as well as cabin pressurization.”
According to Honeywell, this integrated approach, implemented in the mid-2000s, allowed Lockheed Martin, the F-35 prime contractor, to reduce the aircraft’s weight by approximately 1,000 pounds, contributing to the contract award.
Honeywell’s Solution: Upgrade, Don’t Replace
Honeywell advocates for upgrading the existing PTMS, citing lower risk and cost compared to designing and installing an entirely new system, which is another option under JPO consideration.
According to Jim Currier, as part of Breaking Defense’s Future of the F-35 Special Video Series, “The upgrade path that we are proposing for our solution reuses 95 percent of the hardware with a simple change out on a few components. None of the interfaces change in the PTMS system. None of the bracketry changes. None of the electrical wiring will change, so it’s a rather straightforward upgrade of existing aircraft to incorporate both the 40 kW solution and then ultimately the 80 kW solution.”
Software is Key: A Near-Term Boost
Initially, Honeywell’s low-risk approach to increasing cooling capacity by 25 percent to 40 kW involves only a straightforward software upgrade, according to Currier. This software solution also extends the life of the F135 engine by reducing engine bleed air usage by approximately 40 percent.
Digital Twin Advantage: The Path to 80kW
For the longer-term goal of reaching 80kW, Honeywell leverages its F-35 PTMS digital twin.
„Based upon the fact that this system is installed on over 1,245 aircraft, we have an accurate digital twin model that we can use with fidelity based upon a million flight hours of experience,” said Currier. „We’ve been able to demonstrate the ability to upgrade to 80 kW of cooling capacity in a straightforward manner, meaning we can do it by reutilizing 95 percent of the existing equipment and 80 percent of the existing software that is used to control the system.”
“There are multiple paths to ultimately get to the 80 kW cooling capacity needs that are required. And, again, it’s done in a very low-cost proven way to enable that capability to go forward.”
Timeline: A Phased Approach
Regarding the timeline, Currier said that Honeywell can reach a 40 kW solution within two to three years, given that it is a software-only upgrade and the physical PTMS is already available. The 80 kW solution would follow two to three years later, a relatively short timeframe made possible by Honeywell’s ability to reuse the majority of hardware and software for the integrated system, allowing the PTMS upgrade to proceed quickly, with low risk, and built on a proven capability flying today.
