Engine of LCA TEJAS

General Electric F404-IN20 engine for the eight pre-production LSP aircraft and two naval prototypes

Initially, it was decided to equip the prototype aircraft with the General Electric F404-GE-F2J3 afterburning turbofan engine. Simultaneously, in 1986, a parallel programme to develop an indigenous powerplant was also launched. Led by the Gas Turbine Research Establishment, the GTRE GTX-35VS, named "Kaveri", was expected to replace the F404 on all production aircraft. However, progress in the Kaveri development programme was slowed by technical difficulties.
Development snags with the Kaveri resulted in the 2003 decision to procure the uprated F404-GE-IN20 engine for the eight pre-production LSP aircraft and two naval prototypes. General Electric was awarded a US$105 million contract in 2004 for development engineering and production of 17 -IN20 engines, delivery of which began in 2006. The F404-GE-IN20 was trial-installed on the Tejas and the engine generated more than 19,000 pounds (85 kN) uninstalled thrust and completed 330 hours of Accelerated Mission testing, equivalent of 1,000 hours of flight operation. In 2007, an additional 24 F404-IN20 afterburning engines were ordered to power the first operational squadron of Tejas fighters.^[26]
In mid-2004, the Kaveri failed its high-altitude tests in Russia, ending the last hopes of introducing it with the first production Tejas aircraft.^{[N 6]} In February 2006, the ADA awarded a contract to the French aircraft engine company Snecma for technical assistance in working out the Kaveri's problems.^[7] The Kaveri engine based on Snecma’s new core, an uprated derivative of the M88-2 engine that powers the French Rafale fighter, providing 83–85 kilonewtons (kN) of maximum thrust was being considered a third option by DRDO. This led the IAF to object that since Snecma had already developed the core of the engine, the DRDO will not be participating in any joint development but merely providing Snecma with an indigenous stamp.^[27]
In 2008, it was announced that the Kaveri would not be ready in time for the Tejas, and that an in-production powerplant would have to be selected^[28] in the 95 to 100 kilonewton (kN) (21,000–23,000 lbf) range to allow the aircraft to perform combat maneuvers with optimal weapons load. The contenders were the Eurojet EJ200 and the General Electric F414.^[29] IAF sources said that the airframe will have to be redesigned to accommodate the heavier engine, which is to take up to three-four years.^[30]
After evaluation and acceptance of the technical offer provided by both Eurojet and GE Aviation, the commercial quotes were compared in detail and GE Aviation was declared as the lowest bidder. The deal will cover purchase of 99 GE F414 engines. The initial batch will be supplied by GE and the remainder will be manufactured in India under a transfer of technology arrangement.^[

Engine of F-35

F-35B's thrust vectoring nozzle and lift fan

 

The engine used on the F-35 is the Pratt & Whitney F135. An alternative engine, the General Electric/Rolls-Royce F136, was under development until December 2011 when the manufacturers canceled the project. Neither the F135 or F136 engines are designed to supercruise in the F-35,however the F-35 can achieve a limited supercruise of Mach 1.2 for 150 miles. 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" during development. Turbine bearing health will be monitored with thermoelectric-powered sensors.
The F-35 has a maximum speed of over Mach 1.6. With a maximum takeoff weight of 60,000 lb (27,000 kg), the Lightning II is considerably heavier than the lightweight fighters it replaces. In empty and maximum gross weights, it more closely resembles the single-seat, single-engine Republic F-105 Thunderchief, which was the largest single-engine fighter of the Vietnam war era. The F-35's modern engine delivers over 60 percent more thrust in an aircraft of the same weight so that in thrust to weight and wing loading it is much closer to a comparably equipped F-16.
The STOVL F-35B is outfitted with the Rolls-Royce LiftSystem, designed by Lockheed Martin and developed by Rolls-Royce. This system more resembles the Russian Yak-141 and German VJ 101D/E than the preceding STOVL Harrier Jump Jet and the Rolls-Royce Pegasus engine. The Lift System is composed of a lift fan, drive shaft, two roll posts and a "Three Bearing Swivel Module" (3BSM). 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.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.
F136 funding came at the expense of other parts of the program, impacting on unit costs. 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.Pratt & Whitney has tested 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) of early F135s. The F135 has demonstrated a maximum thrust of over 50,000 lbf (220 kN) during testing;making it the most powerful engine ever installed in a fighter aircraft as of 2010.