Engines
The F-35's main engine is the Pratt & Whitney F135. The General Electric/Rolls-Royce F136 was under development as an alternative engine until December 2011 when the manufacturers canceled work on it.[210][211] The F135/F136 engines are not designed to supercruise in the F-35,[212] but the F-35 can achieve a limited supercruise of Mach 1.2 for 150 miles.[213] The STOVL versions of both power plants use the Rolls-Royce LiftSystem, designed by Lockheed Martin and developed to production by Rolls-Royce. This system is more like the Russian Yak-141 and German VJ 101D/E than the preceding generation of STOVL designs,[214][215] such as the Harrier Jump Jet in which all of the lifting air went through the main fan of the Rolls-Royce Pegasus engine.[216]
The Lift System is composed of a lift fan, drive shaft, two roll posts and a "Three Bearing Swivel Module" (3BSM).[217] The 3BSM is a thrust vectoring nozzle which allows the main engine exhaust to be deflected downward at the tail of the aircraft. The lift fan is near the front of the aircraft and provides a counterbalancing thrust using two counter-rotating blisks.[218] It is powered by the engine's low-pressure (LP) turbine via a drive shaft and gearbox. Roll control during slow flight is achieved by diverting unheated engine bypass air through wing-mounted thrust nozzles called Roll Posts.[219][220] Like lift engines, the added lift fan machinery increases payload capacity during vertical flight, but is dead weight during horizontal flight. The cool exhaust of the fan also reduces the amount of hot, high-velocity air that is projected downward during vertical take off, which can damage runways and aircraft carrier decks.[citation needed]
To date, F136 funding has come at the expense of other parts of the program, reducing the number of aircraft built and increasing their costs.[221] The F136 team has claimed that their engine has a greater temperature margin which may prove critical for VTOL operations in hot, high altitude conditions.[222]
Pratt & Whitney is also testing higher thrust versions of the F135, partly in response to GE's claims that the F136 is capable of producing more thrust than the 43,000 lbf (190 kN) supplied by early F135s. The F135 has demonstrated a maximum thrust of over 50,000 lbf (220 kN) during testing.[223] The F-35's Pratt & Whitney F135 is the most powerful engine ever installed in a fighter aircraft.[224]
The F135 is the second (radar) stealthy afterburning jet engine and like the Pratt & Whitney F119 from which it was derived, has suffered from pressure pulsations in the afterburner at low altitude and high speed or "screech". In both cases this problem was fixed during development of the fighter program.[225]
Turbine bearing health in the engine will be monitored with thermoelectric powered wireless sensors.[226]

Most expensive aircraft ever, apparently.