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Pratt & Whitney F135
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Pratt & Whitney F135
The Pratt & Whitney F135 is an afterburning turbofan developed for the Lockheed Martin F-35 Lightning II, a single-engine strike fighter. It has two variants; a Conventional Take-Off and Landing (CTOL) variant used in the F-35A and F-35C, and a two-cycle Short Take-Off Vertical Landing (STOVL) variant used in the F-35B that includes a forward lift fan. The first production engines were delivered in 2009.
Developed from the Pratt & Whitney F119 engine used on the F-22 Raptor, the F135 produces around 28,000 lbf (125 kN) of thrust and 43,000 lbf (191 kN) with afterburner. The F135 competed with the General Electric/Rolls-Royce F136 to power the F-35.
The F135 originated with Lockheed Corporation Skunk Works, with efforts to develop a stealthy STOVL strike fighter for the U.S. Marine Corps under a 1986 DARPA project under the auspices of the Advanced STOVL (ASTOVL) program, an early progenitor of the Joint Strike Fighter (JSF) that resulted in the F-35. Lockheed engineer Paul Bevilaqua developed and eventually patented a concept aircraft and a propulsion system called the Shaft-Driven Lift Fan (SDLF), and then turned to Pratt & Whitney (P&W) to build a demonstrator engine. The ground test demonstrator used the first stage fan from a F119 engine for the lift fan. The engine fan and core from the F100-PW-220 were used for the core of the demonstrator engine, and the larger low-pressure turbine from the F100-PW-229 was used for the low-pressure turbine of the demonstrator engine. The larger turbine was used to provide the additional power required to operate the lift fan through the low-pressure spool shaft, which would be engaged by a clutch in STOVL mode. Finally, a variable thrust deflecting nozzle was added to complete the "F100-229-Plus" demonstrator engine. This ground demonstrator engine proved the shaft-driven lift fan concept and led to the development of the eventual JSF engine.
ASTOVL continued under the Common Affordable Lightweight Fighter (CALF) program in 1993 before eventually being merged into the Joint Advanced Strike Technology (JAST), which was renamed JSF in 1995; under the JSF program, contracts for flightworthy concept demonstrator aircraft were awarded in 1996 to Lockheed Martin and Boeing for the air vehicle designs and P&W for the initial propulsion system. P&W developed the JSF engine from their F119 turbofan, which powers the F-22 Raptor, as the "F119-JSF". A flightworthy prototype system that incorporated the shaft-driven lift fan, designated "YF119-PW-611", was tested on the Lockheed Martin X-35 concept demonstrator aircraft and first flew in 2000. P&W also made another prototype, the "YF119-PW-614", for the competing Boeing X-32 which had direct lift system. In flight tests, the X-35B was able to demonstrate STOVL by taking off in 500 ft (150 m), then flew supersonic before landing vertically. The X-35 concept beat the X-32 for the JSF competition and the YF119-611 would form the basis for the F135, which integrates the F119 core with new components optimized for the JSF.
The F135 team is made up of Pratt & Whitney, Rolls-Royce and Hamilton Sundstrand. Pratt & Whitney is the prime contractor for the main engine, and systems integration. Rolls-Royce is responsible for the vertical lift system for the STOVL aircraft. Hamilton Sundstrand is responsible for the electronic engine control system, actuation system, PMAG, gearbox, and health monitoring systems. Woodward, Inc. is responsible for the fuel system. The F135 is assembled at a plant in Middletown, Connecticut. Some parts of the engine are made in Longueuil, Quebec, Canada, and in Poland. The first production propulsion system for operational service was scheduled for delivery in 2007 with the purpose of serving the U.S., UK, and other international customers. The initial F-35s went into production with the F135 engines, but the GE/Rolls-Royce team planned to develop a replacement F136 engine in July 2009. In 2010, the Pentagon planned for the two propulsion systems to be competitively tendered. However, since 2006 the Defense Department has not requested funding for the alternate F136 engine program, but Congress has maintained program funding.
As of 2009, P&W developed a more durable version of the F135 engine to increase the service life of key parts. The life expectancy of the parts was reduced because the hot sections of the engine (combustor and high-pressure turbine blades specifically) ran hotter than expected. The test engine is designated XTE68/LF1, and testing is expected to begin in 2010. This redesign has caused "substantial cost growth".
P&W expected to deliver the F135 below the cost of the F119, even though it was a more powerful engine. However, in February 2013 a cracked turbine blade was found during a scheduled inspection. The crack was caused by operating at high turbine temperatures for longer periods than usual. In December 2013 the hollow first stage fan blisk failed at 77% of its expected life during a ground test. It was to be replaced by a solid part adding 6 lb (2.7 kg) in weight. In 2013, a former P&W employee was caught attempting to ship "numerous boxes" of sensitive information about the F135 to Iran.
Despite the troubles, the 100th engine was delivered in 2013. LRIP-6 was agreed in 2013 for $1.1 billion for 38 engines of various types, which helped to decrease the unit cost.
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Pratt & Whitney F135
The Pratt & Whitney F135 is an afterburning turbofan developed for the Lockheed Martin F-35 Lightning II, a single-engine strike fighter. It has two variants; a Conventional Take-Off and Landing (CTOL) variant used in the F-35A and F-35C, and a two-cycle Short Take-Off Vertical Landing (STOVL) variant used in the F-35B that includes a forward lift fan. The first production engines were delivered in 2009.
Developed from the Pratt & Whitney F119 engine used on the F-22 Raptor, the F135 produces around 28,000 lbf (125 kN) of thrust and 43,000 lbf (191 kN) with afterburner. The F135 competed with the General Electric/Rolls-Royce F136 to power the F-35.
The F135 originated with Lockheed Corporation Skunk Works, with efforts to develop a stealthy STOVL strike fighter for the U.S. Marine Corps under a 1986 DARPA project under the auspices of the Advanced STOVL (ASTOVL) program, an early progenitor of the Joint Strike Fighter (JSF) that resulted in the F-35. Lockheed engineer Paul Bevilaqua developed and eventually patented a concept aircraft and a propulsion system called the Shaft-Driven Lift Fan (SDLF), and then turned to Pratt & Whitney (P&W) to build a demonstrator engine. The ground test demonstrator used the first stage fan from a F119 engine for the lift fan. The engine fan and core from the F100-PW-220 were used for the core of the demonstrator engine, and the larger low-pressure turbine from the F100-PW-229 was used for the low-pressure turbine of the demonstrator engine. The larger turbine was used to provide the additional power required to operate the lift fan through the low-pressure spool shaft, which would be engaged by a clutch in STOVL mode. Finally, a variable thrust deflecting nozzle was added to complete the "F100-229-Plus" demonstrator engine. This ground demonstrator engine proved the shaft-driven lift fan concept and led to the development of the eventual JSF engine.
ASTOVL continued under the Common Affordable Lightweight Fighter (CALF) program in 1993 before eventually being merged into the Joint Advanced Strike Technology (JAST), which was renamed JSF in 1995; under the JSF program, contracts for flightworthy concept demonstrator aircraft were awarded in 1996 to Lockheed Martin and Boeing for the air vehicle designs and P&W for the initial propulsion system. P&W developed the JSF engine from their F119 turbofan, which powers the F-22 Raptor, as the "F119-JSF". A flightworthy prototype system that incorporated the shaft-driven lift fan, designated "YF119-PW-611", was tested on the Lockheed Martin X-35 concept demonstrator aircraft and first flew in 2000. P&W also made another prototype, the "YF119-PW-614", for the competing Boeing X-32 which had direct lift system. In flight tests, the X-35B was able to demonstrate STOVL by taking off in 500 ft (150 m), then flew supersonic before landing vertically. The X-35 concept beat the X-32 for the JSF competition and the YF119-611 would form the basis for the F135, which integrates the F119 core with new components optimized for the JSF.
The F135 team is made up of Pratt & Whitney, Rolls-Royce and Hamilton Sundstrand. Pratt & Whitney is the prime contractor for the main engine, and systems integration. Rolls-Royce is responsible for the vertical lift system for the STOVL aircraft. Hamilton Sundstrand is responsible for the electronic engine control system, actuation system, PMAG, gearbox, and health monitoring systems. Woodward, Inc. is responsible for the fuel system. The F135 is assembled at a plant in Middletown, Connecticut. Some parts of the engine are made in Longueuil, Quebec, Canada, and in Poland. The first production propulsion system for operational service was scheduled for delivery in 2007 with the purpose of serving the U.S., UK, and other international customers. The initial F-35s went into production with the F135 engines, but the GE/Rolls-Royce team planned to develop a replacement F136 engine in July 2009. In 2010, the Pentagon planned for the two propulsion systems to be competitively tendered. However, since 2006 the Defense Department has not requested funding for the alternate F136 engine program, but Congress has maintained program funding.
As of 2009, P&W developed a more durable version of the F135 engine to increase the service life of key parts. The life expectancy of the parts was reduced because the hot sections of the engine (combustor and high-pressure turbine blades specifically) ran hotter than expected. The test engine is designated XTE68/LF1, and testing is expected to begin in 2010. This redesign has caused "substantial cost growth".
P&W expected to deliver the F135 below the cost of the F119, even though it was a more powerful engine. However, in February 2013 a cracked turbine blade was found during a scheduled inspection. The crack was caused by operating at high turbine temperatures for longer periods than usual. In December 2013 the hollow first stage fan blisk failed at 77% of its expected life during a ground test. It was to be replaced by a solid part adding 6 lb (2.7 kg) in weight. In 2013, a former P&W employee was caught attempting to ship "numerous boxes" of sensitive information about the F135 to Iran.
Despite the troubles, the 100th engine was delivered in 2013. LRIP-6 was agreed in 2013 for $1.1 billion for 38 engines of various types, which helped to decrease the unit cost.
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