Lockheed Martin rolled out the first short take-off and vertical landing F-35B Joint Strike Fighter on 18 December. The aircraft is to begin hover pit testing early in the new year, leading to a first flight scheduled for May 2008.
Aircraft BF-1, clearly fresh off the final-assembly line at Fort Worth, Texas and still unpainted for the roll-out, is essentially complete and ready to begin ground testing, said Dan Crowley, Lockheed executive vice-president and F-35 programme general manager. "We are down to six parts, all small stuff like high-temperature grommets."
The Pratt & Whitney F135 engine and Rolls-Royce shaft-driven lift fan were installed for the roll-out, but will be replaced before hover pit testing begins, says Crowley. The F135 will be replaced with an engine that has been proof-tested to ensure it is not susceptible to high-cycle fatigue turbine-blade failure. The lift fan will be replaced because of a "minor defect" in the contra-rotating fan, he adds.
Lockheed plans to move BF-1 to the fuel barn for tank checks after the roll-out. This will be followed by ground vibration testing, after which the aircraft will move to the hover pit for propulsion system testing. The landing gear will be clamped into fixtures to measure forces as the lift system is tested. Lockheed does not intend to perform vertical take-offs and landings before beginning flight testing.
Flight tests will begin with conventional take-offs and landings and will "build down" to vertical flights, a technique used by Boeing during testing of its rival X-32 JSF concept demonstrator. Transitions between wingborne and jetborne flight will begin at higher altitudes and move to progressively lower altitudes until there is sufficient confidence to perform a vertical landing.
The start of flight testing is a criterion for the release of full funding for the first six production F-35Bs, which will be delivered to the US Marine Corps for training, beginning in 2011. Initial operational capability is scheduled for 2012. The UK Royal Air Force and Royal Navy and Italian air force and navy also plan to buy the STOVL JSF.