There are actually three different variants of the F135: One for conventional takeoffs 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 stand up to the saltwater environment of shipboard life. The STOVL engine, however, is a completely different animal. Developed in collaboration with Rolls-Royce, this engine features a 3 Bearing Swivel Module that acts as a thrust vectoring nozzle that, coupled with a lift fan in the front of the aircraft, facilitates vertical lift-off just like Harrier AV-8B Jump Jets of old.
Besides performance, reliability was also a key initiative in F135 development. To that end, fewer parts were used compared to similar engines and it’s been said that all field-replaceable parts and maintenance can be negotiated with six common tools available at any hardware store. Also present onboard is a Health Management System that transmits real-time data to maintenance personnel on the ground, who can prepare for and ready any necessary parts before the aircraft even lands, reducing downtime.
For the time being, a repower for the stealthy jet has been shelved, but the F135 is undergoing an Engine Core Upgrade that will involve thermal management to address a well-known overheating conundrum, as well as increased capacity to generate additional electricity that’s required for the overall jet’s Block 4 upgrade that’s now underway.