Engineering:Pratt & Whitney F135

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Short description: Afterburning turbofan aircraft engine
F135
Sdd f135 018.jpg
F135 engine during the JSF System Development and Demonstration (SDD) phase
Type Turbofan
National origin United States
Manufacturer Pratt & Whitney
Major applications Lockheed Martin F-35 Lightning II
Developed from Pratt & Whitney F119

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 [1] that includes a forward lift fan. The first production engines were delivered in 2009.[2]

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.[3][4] The F135 competed with the General Electric/Rolls-Royce F136 to power the F-35.

Development

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 program. Lockheed employee Paul Bevilaqua developed and patented[5] a concept aircraft and propulsion system, and then turned to Pratt & Whitney (P&W) to build a demonstrator engine.[6] The ground test demonstrator used the first stage fan from a F119 engine for the lift fan. The engine fan and core from the F100-220 were used for the core of the demonstrator engine, and the larger low-pressure turbine from the F100-229 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. 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.[7]

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.

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.[8] The F135 is assembled at a plant in Middletown, Connecticut. Some parts of the engine are made in Longueuil, Quebec, Canada,[9] and in Poland.[10]

The F135-PW-600 engine mockup with lift fan, roll posts, and rear vectoring nozzle, as designed for the F-35B V/STOL variant, at the Paris Air Show, 2007

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.[11]

An F135-PW-100 powerplant being tested at AEDC

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.[12] This redesign has caused "substantial cost growth".[13]

P&W expected to deliver the F135 below the cost of the F119, even though it was a more powerful engine.[14] 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.[15] 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.[16] In 2013, a former P&W employee was caught attempting to ship "numerous boxes" of sensitive information about the F135 to Iran.[17]

Despite the troubles, the 100th engine was delivered in 2013.[18] LRIP-6 was agreed in 2013 for $1.1 billion for 38 engines of various types, which helped to decrease the unit cost.[19]

Air Force Lt. Gen. Christopher C. Bogdan, the executive officer of the F-35 program, has called out P&W for falling short on manufacturing quality of the engines and slow deliveries.[20] His deputy director Rear Admiral Randy Mahr said that P&W stopped their cost-cutting efforts after "they got the monopoly".[21] In 2013 the price of the F135 increased by $4.3 billion.[22]

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. Bogdan supported P&W'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 they stood behind their product even though they were not given access to the parts to do their own testing. 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"[23][24][25]

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.[26] During high g-force maneuvering three weeks before the flight, flexing of the engine caused excessive rubbing at the seal between the fan blisk and the fan stator initiating the impending failure. The rub caused a temperature of over 1,000 °C (1,900 °F), well beyond the material limit of 540 °C (1,000 °F). Micro cracks appeared in third-stage fan blades, according to program manager Christopher Bogdan, causing blades to separate from the disk. The failed blades punctured a fuel tank and hot air mixing with fuel caused the fire.[27][28][29] 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.[30]

Pratt & Whitney managed to meet their 2015 production goals, but "recurring manufacturing quality issues" in turbine blades and electronic control systems required engines to be pulled from the fleet.[31]

Design

Thrust vectoring nozzle of the F135-PW-600 STOVL variant
Diagram of F-35B and smaller powered lift aircraft

Derived from the F119 engine, the F135 is a mixed-flow afterburning turbofan with a new fan and LP turbine.[32]

There are two F135 variants: the -100 and the -600 versions.[1] A -400 version is mentioned, similar to the -100, the main difference being the use of salt-corrosion resistant materials.[33][34] The -600 is described below with an explanation of the engine configuration changes that take place for hovering. The engine and Rolls-Royce LiftSystem make up the Integrated Lift Fan Propulsion System (ILFPS).[35]

The vertical thrust for the STOVL version is obtained from a two-stage lift fan (about 46%[36]) in front of the engine, a vectoring exhaust nozzle (about 46%[36]), and a nozzle in each wing using fan air from the bypass duct (about 8%[36]). These contributions to the total lift are based on thrust values of 18,680 lbf (83.1 kN), 18,680 lbf (83.1 kN) and 3,290 lbf (14.6 kN) respectively.[36] Another source gives thrust values of 20,000 lbf (89 kN), 18,000 lbf (80 kN), and 3,900 lbf (17 kN) respectively.[37]

In this configuration most of the bypass flow is ducted to the wing nozzles, known as roll posts. Some is used for cooling the rear exhaust nozzle, known as the 3-bearing swivel duct nozzle (3BSD).[38] At the same time an auxiliary inlet is opened on top of the aircraft to provide additional air to the engine with low distortion during the hover.[32]

The low pressure (LP) turbine drives the lift fan through a shaft extension on the front of the LP rotor and a clutch. The engine operates as a separate flow turbofan with a higher bypass ratio.[39] The power to drive the fan—about 30,000 shp (22,000 kW)[39]—is obtained from the LP turbine by increasing the hot nozzle area.[39]

A higher bypass ratio increases the thrust for the same engine power as a fundamental consequence of transferring power from a small diameter propelling jet to a larger diameter one.[40] When the F135 is providing vertical lift using the increased bypass ratio from the lift fan, the thrust augmentation is 50%[36] with no increase in fuel flow. Thrust augmentation is 52%[36] in conventional flight when using the afterburner, but with a large increase in fuel flow.

The transfer of approximately ​1⁄3[41] of the power available for hot nozzle thrust to the lift fan reduces the temperature and velocity of the rear lift jet impinging on the ground.[41] The F-35 can achieve a limited 100% throttle cruise without afterburners of Mach 1.2 for 150 miles (240 km; 130 nmi).[42]

Like the F119, the F135 has a stealthy augmentor where traditional spray bars and flameholders are replaced by thick curved vanes coated with ceramic radar-absorbent materials (RAM). Afterburner fuel injectors are integrated into these vanes, which block line-of-sight of the turbines, contributing to aft-sector stealth. The axisymmetric nozzle consists of fifteen partially overlapping flaps that create a sawtooth pattern at the trailing edge. This creates shed vortices and reduces the infrared signature of the exhaust plume. The effectiveness is reportedly comparable to that of the F119's wedge nozzles, while being substantially more cost effective and lower maintenance.[43]

The engine uses thermoelectric-powered sensors to monitor turbine bearing health.[44]

Improving engine reliability and ease of maintenance is a major objective for the F135. The engine has fewer parts than similar engines, which improves reliability. All line-replaceable components (LRCs) can be removed and replaced with a set of six common hand tools.[45] The F135's health management system is designed to provide real time data to maintainers on the ground. This allows them to troubleshoot problems and prepare replacement parts before the aircraft returns to base. According to Pratt & Whitney, this data may help drastically reduce troubleshooting and replacement time, as much as 94% over legacy engines.[46]

Planned improvements

Although no service has issued a requirement for an upgraded engine, Pratt and Whitney is cooperating with the US Navy on a two-block improvement plan for the F135 engine. The goals of Block 1 are a 7–10% increase in thrust and a 5–7% lower fuel burn. The plans include better cooling technology for turbine blades; this would increase the longevity of the engine and substantially reduce maintenance costs. The goal of Block 2 is to work with the US Air Force's Adaptive Engine Transition Program, with the intention of introducing technology for an engine rated at 45,000 lb of thrust, to be used in a sixth-generation fighter.[47]

Growth options

GO1

At the end of May 2017 Pratt and Whitney announced the F135 Growth Option 1 had finished testing and was available for production. The upgrade requires the changing of the power module on older engines and can be seamlessly inserted into future production engines at a minimal increase in unit cost and no impact to delivery schedule. The Growth Option 1 offers an improvement of 6–10% thrust across the F-35 flight envelope while also getting a 5–6% fuel burn reduction.[48]

GO2

In June 2018, United Technologies, parent company of P&W, announced Growth Option 2.0 to help provide increased power and thermal management system (PTMS) capacity, providing options for operators for instance if they are wishing to upgrade to heavier weapons.[49]

Variants

  • F135-PW-100: Used in the F-35A Conventional Take-Off and Landing (CTOL) variant[50]
  • F135-PW-400: Used in the F-35C naval variant built with salt-corrosion resistant materials[50]
  • F135-PW-600: Used in the F-35B Short Take-Off Vertical Landing variant[50]

Applications

Specifications (F135)

F135-PW-100

Data from Pratt & Whitney,[4] Tinker Air Force Base ,[51] American Society of Mechanical Engineers[52]

General characteristics

  • Type: Two-spool, axial flow, augmented turbofan
  • Length: 220 in (5,590 mm)
  • Diameter: 46 in (1,170 mm) max., 43 in (1,090 mm) at the fan inlet
  • Dry weight: 3,750 lb (1,700 kg)

Components

Performance

F135-PW-600

Data from Pratt & Whitney,[4] Tinker AFB,[51] American Society of Mechanical Engineers[52]

General characteristics

  • Type: Two-spool, axial flow, augmented turbofan with shaft driven remote lift fan
  • Length: 369 in (9,370 mm)
  • Diameter: 46 in (1,170 mm) maximum, 43 in (1,090 mm) fan inlet, 53 in (1,350 mm) lift fan inlet
  • Dry weight:

Components

Performance

  • Maximum thrust:
    • 27,000 lbf (120 kN) military thrust
    • 41,000 lbf (182 kN) with afterburner
    • 40,650 lbf (181 kN) hovering
  • Overall pressure ratio: 28:1 (conventional), 29:1 (powered lift),
  • Turbine inlet temperature: 3,600 °F (1,980 °C; 2,260 K)
  • Power-to-weight ratio:

See also

  • Rolls-Royce LiftSystem

Related development

  • Pratt & Whitney F119

Comparable engines

  • General Electric/Rolls-Royce F136

Related lists

References

  1. ↑ 1.0 1.1 "F135". https://prattwhitney.com/products-and-services/products/military-engines/f135. 
  2. ↑ "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 [yes|permanent dead link|dead link}}]
  3. ↑ "Lockheed Martin F-35 Joint Strike Fighter Succeeds In First Vertical Landing". lockheedmartin.com, Press Release, 18 March 2010.
  4. ↑ 4.0 4.1 4.2 "F135 Engine". f135engine.com. http://www.f135engine.com/docs/B-2-4_F135_SpecsChart.pdf. 
  5. ↑ "Propulsion system for a vertical and short takeoff and landing aircraft" , United States Patent 5209428. PDF of original : http://www.freepatentsonline.com/5209428.pdf
  6. ↑ "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
  7. ↑ Bevilaqua, Paul M. (September 2005). "Joint Strike Fighter Dual-Cycle Propulsion System". Journal of Propulsion and Power 21 (5): 778–783. doi:10.2514/1.15228. https://arc.aiaa.org/doi/abs/10.2514/1.15228. 
  8. ↑ Connors, p. 171.
  9. ↑ Communications and Marketing Branch. "Home - Industry Canada". ic.gc.ca. http://www.ic.gc.ca/eic/site/ic1.nsf/eng/05897.html. 
  10. ↑ "Pratt & Whitney's F-35 Victory Secures 4,250 Connecticut Jobs". Hartford Courant. http://articles.courant.com/2011-02-18/business/hc-pratt-f-35-victory-20110218_1_f135-pratt-whitney-stephanie-duvall. 
  11. ↑ Trimble, Stephen. "US Senate axes F-35 alternate engine". Flightglobal.com, 23 July 2009.
  12. ↑ Harrington, Caitlin. (2009) "Pratt & Whitney starts development of new F-35 test engine". Jane's Defence Weekly, March 27, 2009.
  13. ↑ "Donley: No JSF Alternatives Exist". http://www.aviationweek.com/aw/generic/story_channel.jsp?channel=defense&id=news/awst/2010/03/08/AW_03_08_2010_p28-208867.xml&headline=Donley:%20No%20JSF%20Alternatives%20Exist. [yes|permanent dead link|dead link}}]
  14. ↑ Graham Warwick, Amy Butler "Pentagon Ramps Up Pressure On F-35 Price." Aviation Week, 3 December 2010.
  15. ↑ News Desk (March 2013). "F-35 Lightning II Resume Flying – 'Blade Crack Caused By Stressful Testing'". defense-update.com. http://defense-update.com/20130301_f-35-grounding-lifted.html. 
  16. ↑ "Investigators Eye Third-Stage Turbine As F-35 Remains Grounded". aviationweek.com. http://aviationweek.com/defense/investigators-eye-third-stage-turbine-f-35-remains-grounded. 
  17. ↑ Dowling, Brian (13 January 2014). "Former Pratt Employee Arrested Trying To Ship F-35 Documents To Iran". The Hartford Courant. http://www.courant.com/business/hc-pratt-whitney-iran-documents-20140113,0,6907892.story. 
  18. ↑ "Press Releases". utc.com. http://www.pw.utc.com/Press/Story/20130618-0200/. 
  19. ↑ Mehta, Aaron (23 October 2013). "Pratt & Whitney, Pentagon Reach $1.1B Deal on F-35 Engines". Gannett Government Media Corporation. http://www.defensenews.com/article/20131023/DEFREG02/310230033. 
  20. ↑ Dowling, Brian (March 26, 2014). "Pentagon criticizes Pratt & Whitney for 'systemic' F-35 production issues". Hartford (Conn.) Courant. http://www.stripes.com/news/us/pentagon-criticizes-pratt-whitney-for-systemic-f-35-production-issues-1.274724. 
  21. ↑ Shalal, Andrea (7 April 2014). "Pratt must push harder to cut F-35 engine cost: Pentagon". Reuters. https://www.reuters.com/article/us-unitedtechnologies-fighter-engine-idUSBREA361K320140407. 
  22. ↑ Shalal, Andrea (17 April 2014). "Cost to buy F-35 up 2 percent; to operate down 9 percent: Pentagon". Thomson Reuters. https://www.reuters.com/article/us-lockheed-fighter-idUSBREA3G27K20140417. 
  23. ↑ Krauskopf, Lewis (29 August 2014). "Pratt halted F-35 engine shipments in May over titanium". Reuters. https://news.yahoo.com/pratt-suspended-f-35-engine-shipments-may-over-210437013--finance.html. 
  24. ↑ Mehta, Aaron (3 September 2014). "F-35 Head: Delays Coming if Test Planes Grounded Through September". Gannett. http://www.defensenews.com/article/20140903/DEFREG02/309030029/F-35-Head-Delays-Coming-Test-Planes-Grounded-Through-September. 
  25. ↑ Capaccio, Tony (29 August 2014). "Pratt & Whitney Halted F-35 Engine Delivery Over Titanium". Bloomberg News. https://www.bloomberg.com/news/2014-08-29/pratt-whitney-halted-f-35-engine-delivery-over-titanium.html. 
  26. ↑ Majumdar, Dave (7 July 2014). "Sources: Engine 'Definitely' To Blame in June F-35 Fire". U.S. Naval Institute. http://news.usni.org/2014/07/07/sources-engine-definitely-blame-june-f-35-fire. 
  27. ↑ Sweetman, Bill, Butler Amy, and Guy Norris, There's the rub, Aviation Week & Space Technology, September 8, 2014, pp.22-23
  28. ↑ Butler, Amy (13 July 2014). "Blade 'Rubbing' At Root of F-35A Engine Fire". Penton. http://aviationweek.com/awin-only/blade-rubbing-root-f-35a-engine-fire. 
  29. ↑ McGarry, Brendan (15 September 2014). "Bogdan: F-35 Engine Fix May be Ready by Year's End". http://www.dodbuzz.com/2014/09/15/bogdan-f-35-engine-may-be-fixed-by-years-end/. 
  30. ↑ Osborn, Kris (31 October 2014). "Pentagon Implements F-35 Engine Fixes". Monster. http://www.dodbuzz.com/2014/10/31/pentagon-implements-f-35-engine-fixes/. 
  31. ↑ Capaccio, Anthony (31 March 2016). "United Technologies' F-35 Engines Found to Have Recurring Flaws". Bloomberg L.P.. https://www.bloomberg.com/news/articles/2016-03-31/united-technologies-f-35-engines-found-to-have-recurring-flaws. 
  32. ↑ 32.0 32.1 "X to F: F-35 Lightning II And Its X-35 Predecessors". codeonemagazine.com. http://www.codeonemagazine.com/article.html?item_id=28. 
  33. ↑ "Pratt & Whitney F135 Turbofan Engine | PowerWeb". http://www.fi-powerweb.com/Engine/PW-F135.html. 
  34. ↑ "The Pratt & Whitney F135". Jane's Aero Engines. Jane's Information Group, 2009 (subscription version, dated 10 July 2009)[yes|permanent dead link|dead link}}].
  35. ↑ National Aeronautic Association (25 February 2002). "Integrated Lift Fan Gets Nod for Collier Trophy". http://naa.aero/userfiles/files/documents/Press%20Releases/Collier%202001%20PR.pdf. 
  36. ↑ 36.0 36.1 36.2 36.3 36.4 36.5 Pratt & Whitney. "Power for F-35B Short Take Off and Vertical Landing (STOVL)". http://www.pw.utc.com/Content/F135_Engine/pdf/b-2-4_me_f135_stovl.pdf. 
  37. ↑ Rolls-Royce plc (2016). "Technology". http://www.rolls-royce.com/products-and-services/defence-aerospace/products/combat-jets/rolls-royce-liftsystem/technology.aspx. 
  38. ↑ "F-35B Lightning II Three-Bearing Swivel Nozzle". codeonemagazine.com. http://www.codeonemagazine.com/article.html?item_id=137. 
  39. ↑ 39.0 39.1 39.2 "Genesis of the F-35 Joint Strike Fighter" Paul M. Bevilaqua, 2009 Wright Brothers Lecture, Journal of Aircraft, Vol. 46, No. 6, November–December 2009
  40. ↑ "V/STOL by Vertifan" William T. Immenschuh, Flight International, 1 October 1964
  41. ↑ 41.0 41.1 "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
  42. ↑ Tirpak, John (November 2012). "The F-35's Race Against Time". Air Force Association. http://www.airforce-magazine.com/MagazineArchive/Pages/2012/November%202012/1112fighter.aspx. "while not technically a "supercruising" aircraft, can maintain Mach 1.2 for a dash of 150 miles without using fuel-gulping afterburners" 
  43. ↑ Katz, Dan (7 July 2017). The Physics And Techniques Of Infrared Stealth. https://aviationweek.com/defense/physics-and-techniques-infrared-stealth. Retrieved 12 April 2019. 
  44. ↑ Swedberg, Claire. "Energy-Harvesting Sensors to Monitor Health of Jet Engines". RFID Journal, 31 May 2011.
  45. ↑ "Pratt & Whitney F135 Press release". http://www.pratt-whitney.com/vgn-ext-templating/v/index.jsp?vgnextoid=2e35288d1c83c010VgnVCM1000000881000aRCRD&prid=95068129982de010VgnVCM100000c45a529f____. 
  46. ↑ Rajagopalan, R., Wood, B., Schryver, M. (2003). Evolution of Propulsion Controls and Health Monitoring at Pratt and Whitney. AIAA/ICAS International Air and Space Symposium and Exposition: The Next 100 Years. 14–17 July 2003, Dayton, Ohio. AIAA 2003-2645.
  47. ↑ Norris, Guy, Power plan, Aviation Week & Space Technology, April 13–26, 2015, p.26
  48. ↑ "Pratt & Whitney Validates Growth Option for F135 Engine". http://www.prnewswire.com/news-releases/pratt--whitney-validates-growth-option-for-f135-engine-300466212.html. 
  49. ↑ Pratt & Whitney launches Growth Option 2.0 upgrade for F135 engine, Air Force Technology, 2018-06-14
  50. ↑ 50.0 50.1 50.2 DP Staff Writer (October 5, 2019). "Pratt & Whitney Awarded with $5.7B F135 Production Contract". DefPost. https://defpost.com/pratt-whitney-awarded-with-5-7b-f135-production-contract/?noamp=mobile. 
  51. ↑ 51.0 51.1 Ray, Mike W. (20 July 2012). "F135 engine depot stand-up has started". www.tinker.af.mil. https://www.tinker.af.mil/News/Article-Display/Article/385150/f135-engine-depot-stand-up-has-started/. 
  52. ↑ 52.0 52.1 Langdon, Lee S. (1 April 2007). Fahrenheit 3,600. 129. pp. 34–37. doi:10.1115/1.2007-APR-3. http://memagazineselect.asmedigitalcollection.asme.org/article.aspx?articleid=2683357. 
Bibliography

External links



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