Boeing is set to take an early lead in Joint Strike Fighter flight testing with its X-32A concept demonstrator aircraft (CDA) expected to fly imminently. Lockheed Martin, meanwhile, has delayed the first flight of its X-35B short take-off vertical landing (STOVL) demonstrator to the second quarter of 2001 as a result of lift-fan technical problems.
The conventional take-off and landing (CTOL) version of Boeing's X-32 CDA is due to fly this week after completing vehicle management system (VMS) checks, air vehicle certification and high speed taxiing. It will take off from Palmdale and land at the US Air Force's Edwards test centre after a 45min test flight.
Boeing's X-32B STOVL version is now expected to fly in the first quarter of next year, with VMS, engine accelerated mission test and propulsion system STOVL mode testing due to finish by the end of this year. "If we complete this, we'll fly in the first part of the first quarter; if we miss, the chances are it will be the latter part," says Mike Heinz, Boeing JSF deputy programme manager.
First flight of Lockheed Martin's CTOL X-35A is targeted for early October, followed a month later by the aircraft-carrier configured X-35C. The X-35A will conduct around a third of the planned 100h-plus flight test programme before starting a six- to eight-week conversion to the STOVL X-35B, now due to fly between April and June 2001.
"Its not a race to see who gets into the air first; we intend to fly when we're ready, but we do need to complete the flight testing within the time allocated," says Harry Blot, Lockheed Martin JSF deputy programme manager.
A final JSF selection had been due by mid-2001, but could slip to September to allow the programme office time to gather data and accommodate a change in the US administration.
Testing of the Lockheed Martin STOVL powerplant has suffered a further technical hitch with the failure of a retaining nut on the clutch bearing retainer while under torque. The nut impacted on the case and metal shavings were detected by the chip detector, resulting in an engine shutdown. The company has played down the problem as normal for a development programme, adding that the lift-fan has already clocked up 300h during Pratt & Whitney tests.
Source: Flight International