General Electric and Pratt & Whitney are fighting tooth-and-nail over jet engines—specifically, whose will power the hundreds of F-35 Lightning II stealth fighters operated by the U.S. military and its allies across the globe. Given that the F-35 is the most expensive defense program in history, the stakes are high.
Presently, the F-35 uses Pratt & Whitney’s F135 turbofan engine, or the F-135-600 version for the Marine’s F-35B jump jet model. Developed from the F119 engine used by the F-22 Raptor stealth fighter, the F135 can generate 28,000 pounds of thrust, or 43,000 with afterburner; and withstand 3600 degrees Fahrenheit of heat. The almost two-ton engine is assembled in a factory in Middletown, Connecticut, with some subcomponent built in Canada and Poland.
The hugely expensive and much delayed Block 4 upgrade to the F-35 currently in progress, however, requires an engine that can generate more electricity for systems integrated into the F-35. Better thermal management is also required, as F-35s already struggle sometimes with the current load, and the addition of Block 4 systems will increase that burden. Thus, a failure to improve the engine would reportedly raise operating costs and reduce engine life.
The F135 has had a bumpy ride recently. The crash of a hovering F-35B jump jet on December 14, 2022 led to a freeze on F135 deliveries 13 days later. Subsequently, Pratt & Whitney identified engine vibrations (“harmonic resonance”) causing the failure of a high-pressure fuel tube as the culprit. A fix dampening engine vibrations is being implemented going forward. Pratt & Whitney claims deliveries may resume in March, though it’s unclear how fixes could be retrofitted to already delivered engines.
Earlier, there were also reports that sustained use of the afterburners could damage the F-35’s tail, leading the Marine Corps and Navy to quietly self-impose a 40- to 80-second time limit on after burner usage.
The debate now concerns whether the F135 engine should receive an evolutionary update, or be entirely replaced with a new adaptive cycle-engine that can reconfigure itself midflight to optimize fuel efficiency or thrust as needed. (end of excerpt)
(Click here for the full story, on the Popular Mechanics website.)
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