Graham Warwick/WASHINGTON DC

Lockheed Martin has begun hover pit testing of its X-35B short take-off and vertical landing (STOVL) Joint Strike Fighter (JSF) demonstrator.


On the first run, the Pratt & Whitney JSF119-611 engine was spooled up to idle, the shaft-driven lift fan engaged and vectoring nozzles commanded. Hover pit testing at Palmdale, California, will lead to a first flight in June.

Boeing, meanwhile, expects to conduct the first full-power hover pit test of its X-32B direct-lift STOVL JSF demonstrator this week. The aircraft is set to fly by the end of this month.

Lockheed Martin's X-35B has been converted from the X-35A conventional take-off and landing (CTOL) demonstrator by installation of the Rolls-Royce lift fan, three-bearing swivelling aft nozzle and wing "roll post" ducts.

The X-35A completed 27.4h of CTOL tests before being grounded, reaching Mach 1.05. Lockheed Martin is now expanding the "up-and-away" flight envelope as part of X-35C carrier variant (CV) testing at the US Navy's Patuxent River, Maryland, test centre.

By the end of February, the X-35C had logged 42h and reached M1.15. "We intend to go further," says X-35 product manager Rick Rezabek. The team plans to complete over 200 field carrier landing practice (FCLP) tests at Pax River to demonstrate the X-35C's carrier suitability. "So far, we are dead on predictions," says Rezabeck.

Boeing completed its CV tests in December. The company flew 97 FCLP approaches as part of X-32A CTOL demonstrator testing at Edwards AFB, California.

Lockheed Martin chose to perform FCLP tests at the sea-level Pax site because engine response "is very dependent on altitude", Rezabeck says. "Engine response is as much a factor in an off-nominal approach as aerodynamics."

Boeing will test X-32B STOVL at Pax after initial flights at Edwards, to avoid loss of thrust.

Source: Flight International