Forum: F-35 Engine

DATE:19/10/10
SOURCE:Flight International
P&W details success with F135 engine STOVL tests
By Stephen Trimble

Pratt & Whitney has completed a key test in the process to clear the initial service release for the short take-off and vertical landing version of the F135 engine powering the Lockheed Martin F-35 Joint Strike Fighter.

The high temperature margin test at the Arnold Engineering Development Center showed the STOVL F135 can survive despite exceeding non-augmented thrust by 28%, says Bennett Croswell, P&W vice-president.

Despite exceeding thrust limits, a post-test inspection revealed no signs of damage or structural fatigue, Croswell says. The company shipped the engine straight to its West Palm Beach site in Florida to run a final series of tests with no further repairs or parts changes.

"The purpose of the test is to validate the engine is robust enough to handle even worst-case conditions that it will have over its service life," Croswell says.

Tests on the STOVL version of the F135 should be wrapped up within a few weeks, he says. Initial service release should follow before year-end after P&W staff complete "3,000 or so verification reports", Croswell says.

© Lockheed Martin

Clearing the release milestone is a key step that shifts the F135 STOVL version from development into production.

Although the high-temperature test showed the F135 can withstand power spikes, the engine is designed to operate regularly in the 40,000lb-thrust (178kN) range.

From January, P&W will start tests on a higher-power version of the engine. The XT68LF1 is a technology demonstrator designed to boost engine power by up to 10-15%. The demonstrator will introduce new hot section technology to improve engine power, such as new turbine blades and cooling schemes, Croswell says.

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Pratt Completes F135 Overtemp And Durability Tests Oct 19, 2010 By Graham Warwick

http://www.aviationweek.com/aw/generic/ ... line=Pratt Completes F135 Overtemp And Durability Tests&channel=&from=topicalreports

"Pratt & Whitney has completed tests of the durability and robustness of the F135 short-takeoff-and-vertical-landing (Stovl) propulsion system for the F-35 Joint Strike Fighter, and is preparing for final performance and operability testing to qualify the engine.

Tests included running the engine at turbine temperatures beyond design limits to validate its robustness. The high-temperature margin test at Arnold Engineering Development Center (AEDC) in Tullahoma, Tenn., demonstrated the F135’s potential for thrust growth, says Bennett Croswell, vice president for F119/F135 engine programs.

Ground-test engine FX642 was run in conditions simulating flight at 30,000 ft. and Mach 1.5, with the turbine at 50F above maximum metal temperature and the high and low spools spinning at 100% speed. “It ran for 5 minutes and was then inspected. There was no distress and no required maintenance,” Croswell says.

The engine was run both augmented and dry (non-augmented), and at the above-design turbine temperature produced 128% of the specification dry thrust, Croswell says. This “overtemp” test, not conducted during earlier qualification of the conventional-takeoff-and-landing F135, demonstrates the engine’s margin for thrust growth, he says.

Engine FX642 has been shipped to Pratt’s West Palm Beach, Fla., site for the remaining 35 hr. of sea-level performance and operability testing of the Stovl propulsion system.

Ground-test engine FX648, meanwhile, completed durability testing on Oct. 15, logging more than 2,000 tactical cycles, equivalent to about four years’ use, Croswell says.

Durability testing of the Stovl propulsion system included 1,220 engagements of the lift-fan clutch, he says. FX648 has been shipped to Pratt’s Hartford, Conn., plant for tear-down, but Croswell says inspection at the West Palm Beach site following completion of durability testing showed the engine was “looking good.”

Pratt expects to complete qualification testing in time to achieve initial service release (ISR) for the F135 Stovl propulsion system by the end of the year. The CTOL F135 received ISR in February and the production engine has already flown in the first F-35C carrier variant.

General Electric and Rolls-Royce, meanwhile, are to begin testing their F136 alternate engine with the Stovl lift system for the first time in December, on a specially built test stand at GE’s Peebles, Ohio, facility. Airfoil damage that forced the shutdown of an F136 endurance test in late September has been traced to an over-tight fan seal clearance (Aerospace DAILY, Sept. 29)."