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The Pratt & Whitney F135 is an afterburning turbofan developed for the Lockheed Martin F-35 Lightning II single-engine strike fighter. The F135 family has several distinct variants, including a conventional, forward thrust variant and a multi-cycle STOVL variant that includes a forward lift fan. The first production engines were scheduled to be delivered in 2009.〔"F135 Engine Exceeds 12,000 Engine Test Hours as Pratt & Whitney Prepares to Deliver First Production Engines" (2009). Pratt & Whitney press release. July 28, 2009. (PR Newswire Link )〕 ==Development== The origins of the F135 lie with the Lockheed Corporation Skunk Works's efforts to develop a stealthy STOVL strike fighter for the U.S. Marine Corps under a 1986 DARPA program. Lockheed employee Paul Bevilaqua developed and patented〔("Propulsion system for a vertical and short takeoff and landing aircraft" ), United States Patent 5209428. PDF of original : http://www.freepatentsonline.com/5209428.pdf〕 a concept aircraft and propulsion system, and then turned to Pratt & Whitney (P&W) to build a demonstrator engine.〔"The Shaft Driven Lift Fan Propulsion System For The Joint Strike Fighter" Paul M. Bevilaqua, American Helicopter Society 53rd Annual Forum, Virginia Beach, April 29-May 1, 1997. Fig. 6 Turbine Performance Map〕 The demonstrator used the first stage fan from a F119 engine for the lift fan, the engine fan and core from the F100-220 for the core, and the larger low pressure turbine from the F100-229 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. Finally, a variable thrust deflecting nozzle was added to complete the "F100-229-''Plus''" demonstrator engine. This engine proved the lift-fan concept and led to the development of the current F135 engine.〔Bevilaqua, Paul M. (2005). (One-page preview of ) "Joint Strike Fighter Dual-Cycle Propulsion System." Journal of Propulsion and Power, Vol. 21, 5. pp. 778-783.〕 P&W developed the F135 from their F119 turbofan, which powers the F-22 Raptor, as the "F119-JSF". The F135 integrates the F119 core with new components optimized for the JSF.〔Connors, p. 171.〕 The F135 is assembled at a plant in Middletown, Connecticut. Some parts of the engine are made in Longueuil, Quebec, Canada, and in Poland.〔(【引用サイトリンク】title=Pratt & Whitney's F-35 Victory Secures 4,250 Connecticut Jobs )〕 The first production propulsion system for operational service was scheduled for delivery in 2007. The F-35 will serve the U.S., UK, and other international customers. The initial F-35s will be powered by the F135, but the GE/Rolls-Royce team was developing the F136 turbofan as an alternate engine for the F-35 as of July 2009. Initial Pentagon planning required that after 2010, for the Lot 6 aircraft, the engine contracts will 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.〔Trimble, Stephen. ("US Senate axes F-35 alternate engine" ). Flightglobal.com, 23 July 2009.〕 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. As of 2009, P&W was developing a more durable version of the F135 engine to increase the service life of key parts. These parts are primarily in the hot sections of the engine (combustor and high pressure turbine blades specifically) where current versions of the engine are running hotter than expected, reducing life expectancy. The test engine is designated ''XTE68/LF1'', and testing is expected to begin in 2010.〔Harrington, Caitlin. (2009) "Pratt & Whitney starts development of new F-35 test engine". Jane's Defence Weekly, March 27, 2009.〕 This redesign has caused “substantial cost growth.”〔(Donley: No JSF Alternatives Exist )〕 P&W expects to deliver the F135 below the cost of the F119, even though it is a more powerful engine.〔Graham Warwick, Amy Butler ("Pentagon Ramps Up Pressure On F-35 Price." ) ''Aviation Week'', 3 December 2010.〕 In February 2013 a cracked turbine blade was found during a scheduled inspection. The crack was caused by operating for longer periods than typical at high turbine temperatures. The 100th engine was delivered in 2013.〔(【引用サイトリンク】title=Press Releases )〕 LRIP-6 was agreed in 2013 for $1.1 billion for 38 engines of various types, continuing the unit cost decreases. In 2013, a former P&W employee was caught attempting to ship "numerous boxes" of sensitive information about the F135 to Iran. In December 2013 the hollow first stage fan blisk failed at 77% of its expected life during a ground test. It will be replaced by a solid part adding 6 lb in weight.〔(【引用サイトリンク】title=Investigators Eye Third-Stage Turbine As F-35 Remains Grounded )〕 F-35 program office executive officer Air Force Lt. Gen. Christopher C. Bogdan has called out Pratt for falling short on manufacturing quality of the engines and slow deliveries. His deputy director Rear Admiral Randy Mahr said that Pratt stopped their cost cutting efforts after "they got the monopoly". In 2013 the price of the F135 increased by $4.3 billion. In July 2014 there was an uncontained failure of a fan rotor while the aircraft was preparing for take-off. The parts passed through a fuel tank and caused a fire, grounding the F-35 fleet. The failure was caused by excessive rubbing at the seal between the fan blisk and the fan stator during high-g maneuvering three weeks before the failure. The engine "flex" generated a temperature of 1,900 degrees F in materials designed to fail at 1,000 degrees F. Microcracks appeared in third-stage fan blades, according to program manager Christopher Bogdan, causing blades to separate from the disk; the failed blades punctured the fuel cell and hot air mixing with jet fuel caused the fire.〔Sweetman, Bill, Butler Amy, and Guy Norris, There's the rub, Aviation Week & Space Technology, September 8, 2014, pp.22-23〕 As a short term fix, each aircraft is flown on a specific flight profile to allow the rotor seal to wear a mating groove in the stator to prevent excessive rubbing. In May 2014, Pratt & Whitney discovered conflicting documentation about the origin of titanium material used in some of its engines, including the F135. The company assessed that the uncertainty did not pose a risk to safety of flight but suspended engine deliveries as a result in May 2014. Bogdan supported Pratt's actions and said the problem was now with A&P Alloys, the supplier. The US Defense Contract Management Agency wrote in June 2014 that Pratt & Whitney’s "continued poor management of suppliers is a primary driver for the increased potential problem notifications." A&P Alloys stated that it has not been given access to the parts to do its own testing but stood behind its product. Tracy Miner, an attorney with Boston-based Demeo LLP representing A&P Alloys said, "it is blatantly unfair to destroy A&P’s business without allowing A&P access to the materials in question". 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Pratt & Whitney F135」の詳細全文を読む スポンサード リンク
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