The Pratt & Whitney-led F135 Joint Strike Fighter (JSF) propulsion system team has completed Phase 1risk-reduction tests and is preparing for a quick-fire succession of crucial programme milestones for the conventional take-off and landing (CTOL) and short take-off and vertical landing (STOVL) versions over the next 14 months.

The 10-month risk reduction tests focused on the basic reliability of the engine as well as validating several new design concepts developed for the F135 production configuration. The tests pave the way for the manufacture of 32 production compliant engines for the JSF system development and demonstration (SDD) phase, 20 of which will be flight-test engines.

"We're cutting chips," says F135 engine programmes vice-president Tom Farmer. "We are developing our manufacturing process concurrently with the development of the ground-test programme."

A key modification being tested is a revised lift-fan clutch for the STOVL variant, scheduled for a major SDD-phase test in June. The first production-standard hollow, wide-chord blades for the lift fan, manufactured by Rolls-Royce, will, meanwhile, be tested as a complete set in December. The first full STOVL test engine is due to be run in April next year.

A critical design review to set the production configuration for all variants is scheduled for May, preparing the ground for the first CTOL test engine in October this year. The third flight-test engine is scheduled for delivery to Lockheed Martin for installation in the first CTOL aircraft in the fourth quarter of 2005. The first flight-test engine for the initial STOVL Lockheed Martin F-35 is set for delivery in the first quarter of 2006.

Successful evaluation for the SDD phase depends on the use of a set of test facilities developed specifically for the STOVL version. These include a 29,800kW (40,000hp) electrically powered lift fan test site due to start operations in November, and a test stand to measure thrust loads in the hover mode.

Source: Flight International