F-35 engine: The incredible turbofan that powers the world's most advanced fighter jet

Recent discussions surrounding the armed forces' latest and most technology-laden fighter jet ever, the F-35 Lightning II, prompted manufacturer Lockheed Martin to propose replacing the plane's current engine altogether rather than carrying out a previously planned upgrade program. In a recent interview with Breaking Defense, Greg Ulmer, Lockheed's executive vice president of aerospace, stated, "I'm going to advocate, and I'm advocating for the [Adaptive Engine Transition Program, or AETP], another engine." Ulmer continued, "I think some of the approaches today are very short-term and don't consider a long-term view."

Since the F-35 is expected to fly until the year 2070, one can't blame its pilots for looking to the future, but the fact is that the jet's current Pratt & Whitney F135 turbofan engine is pretty incredible in its own right and, due to budget constraints, will continue to operate the F-35 for the foreseeable future.

The F135's history begins with a strong pedigree since it evolved from the F119 turbofan that powers the F-22 Raptor fighter. First seen in the late 1990s, the F119 has a reputation as the safest fighter engine in US Air Force history. Since the F-35 is powered by only a single engine, it must be robust. In fact, the F135 is rated at 43,000 pounds of thrust while using the afterburner, which is more than the two engines powering a "Top Gun" movie-era F-14 jet combined.

It can also fly vertically

There are actually three different variants of the F135: one for conventional take-offs and landings, one specialized for use on aircraft carriers, and a short take-off and vertical landing (STOVL) version. The conventional and aircraft carrier versions are largely similar, except that the carrier engine has superior corrosion resistance to withstand the onboard saltwater environment. However, the STOVL engine is a completely different animal. Developed in collaboration with Rolls-Royce, this engine has a 3-layer swing module that acts as a thrust vectoring nozzle which, combined with a lift fan at the front of the aircraft, facilitates vertical lift just like the Harrier AV-8B Jump Jets of old.

Besides performance, reliability was also a key initiative in the F135 development. To that end, fewer parts were used compared to similar engines, and it has been said that all field replaceable and serviceable parts can be negotiated with six common tools available at any hardware store. Also on board is a health management system that transmits real-time data to maintenance personnel on the ground, who can prepare and ready necessary parts before the aircraft even lands, reducing downtime.

For now, a repower for the stealth jet has been shelved, but the F135 is undergoing an Engine Core Upgrade that will involve thermal management to solve a well-known overheating conundrum, as well as increased capacity to generate the extra electricity needed for the parent jet's Block 4 upgrade that now is underway.