A Matter of Keeping Cool

The U.S. Department of Defense (DOD) has conceived of an ambitious plan by which to update Lockheed-Martin’s controversial and thus-far lackluster F-35 fighter aircraft. The plan identifies and addresses a key difficulty with which F-35 pilots, maintainers, and tacticians have been faced—the immense demands normal operations place on the aircraft’s cooling system.

The degree of cooling required to mitigate waste-heat from the F-35’s myriad and complex electronic giblets is extensive and ever-increasing. As technologies mature and the exigencies of modern combat compel military leaders to supplement the dizzying complement of cutting-edge sensors, jammers, radars from which the F-35’s ostensible lethality arises, the aircraft’s cooling demands are expected to double.

To better the F-35’s literal and figurative abilities to keep its cool under combat conditions, Pratt & Whitney and Collins Aerospace have proposed a pair of improvements; an upgraded engine power module capable of boosting performance providing sufficient bleed-air to meet the F-35’s cooling needs; and a new, optimized cooling-system that makes more efficient use of engine bleed-air.

Experts from the aforementioned companies posit the proposed upgrades would afford the F-35 a fast and cost-effective means by which to remain formidable over a span of decades.

Rick “Slash” Crecelius, a former F-35 pilot and retired U.S. Navy captain now functioning as Pratt & Whitney’s director for customer integration, remarked: “The F-35 has to be not just equal to the near-peer fighter threat. It has to be superior. But technological advantage is a temporal thing. If we take too long, we start falling behind.”

Pratt & Whitney has proposed an upgrade to its F135 engine—a powerplant the company developed and produces expressly for the F-35. According to Pratt & Whitney, the suggested upgrade would facilitate advantages the likes of: reliability, compatibility with all three F-35 variants, upwards of $40-billion in projected cost savings over the life of the F-35 program, and a projected 2028 delivery date.

The F-35’s upcoming Block-4 modernization initiative will encompass dozens of improvements in areas such as sensing, jamming, communications, and the computer systems by which the antecedent functions are underpinned.

Pentagon officials are considering powering the Block-4 F-35 with what’s known as an adaptive engine—a wholly-new technology apt to cost north of $6-billion to develop and take more than a decade to integrate with the extant F-35 design—not to mention the fleet.

The Pratt & Whitney engineers about the business of developing such an adaptive engine believe the contraption is best suited for a new generation of fighter jets. As a more immediate, affordable, and practical option for the F-35, the plucky engineers have proposed what’s known as the Engine Core Upgrade—an improved power module compatible with the F-35’s current F135 engine.

Having, to date, supported three major upgrades to the F-35’s airframe and payload, Pratt & Whitney’s F135 powerplant has soundly outperformed its original design specifications. Moreover, the worldwide fleet of F135 engines has cumulatively amassed more than 600,000 safe flight-hours—one-million flight-hours if one takes into account the safety record of the F119 mill upon which the F135’s core architecture was based.

Pratt & Whitney’s proposed Engine Core Upgrade boosts the original F135 engine’s performance—to include increased thrust, range via improved aerodynamics and optimized cooling-flows. The proposed upgrade retains some two-thirds of the existing F135 engine’s components—thereby diminishing cost and complexity whilst saving a great deal of time otherwise given over to testing, proving, tooling, and retrofitting.

Pratt & Whitney senior director for F135 strategy Caroline Cooper asserted: “When you leverage that existing production capacity and that sixty to seventy-percent commonality in parts, it’s not a hard putt. You retrofit into the old and produce for the new.”

While a new Pratt & Whitney adaptive engine would occasion a major move forward in fighter jet technology, its benefits to the F-35 fall short of justifying the added time and expense of such an initiative—so stated Jonathan Niemeyer, chief engineer for the F135 program.

Mr. Niemeyer added: “An adaptive engine provides lots of capability, but a lot of it isn’t required based on what our customer is telling us. All those things you’re adding on, they add risk and schedule. If the real threat is a fight on a date that’s soon, our focus has to be on delivering mature, low-risk capability on the schedule the customer is asking for. In my heart-of-hearts, I believe the Engine Core Upgrade is delivering exactly that.”

The Block 4 improvements are expected to keep the F-35 relevant for years in near-peer combat theaters. Nevertheless, the level of investment in the aircraft by the U.S. and its NATO allies, in addition to the conditionally-worrying fact the U.S. intends to fly the F-35 until 2070, speak compellingly to the wisdom of looking circumspectly to the aircraft’s future—in particular, its ability to host emergent offensive and defensive technologies.

Ergo, the F-35s cooling capacity is salient, eminently, to its long-term usefulness. Stated simply, the capability of the F-35’s cooling architectures must increase in direct proportion to the number of energy-hungry, heat-intensive McGuffin’s the aircraft is called upon to carry.

Collins Aerospace associate director of power & controls Henry Wu stated: “Look at how competitive the battlespace is. They want to be able to see farther, to shoot farther and more accurately. And they need the mission equipment to accomplish that. The problem is, the cooling system they have today can’t keep up. If you buy the new radars and jammers without the cooling, you couldn’t really put them on the jet because they wouldn’t work.”

To better serve the F-35’s future cooling needs, Collins has developed the Enhanced Power and Cooling System (EPACS)—a forward-thinking contrivance comprising an air-conditioning unit, an electric power generator, and an Auxiliary Power Unit (APU) engineered to fit within the footprint of the F-35’s extant cooling system.

The key advantage instantiated by the EPACS is the mechanism’s ability to tap bleed air off the F135 engine without too much affecting the powerplant’s performance.

Collins Aerospace vice-president of engineering & technology for power & controls Bill Dolan opined: “If we get the ability to combine the EPACS with the Engine Core Upgrade, we can provide superior results. We [Collins and Pratt & Whitney] know each other. We understand what each other does. There’s a clear advantage, if we can do these things in collaboration, for the end customer.”

FMI: www.prattwhitney.com