Lockheed Martin will roll out the first short take-off and vertical landing F-35B on 18 December, shortly after having resumed flight testing of the Joint Strike Fighter. The first F-35, aircraft AA-1, returned to flight on 7 December, the same day Lockheed began check-out flights with the CATBird avionics testbed.

The first F-35B, aircraft BF-1, is off the assembly-line rolling dolly and on its own gear as Lockheed closes out the last few skins after completing leak testing, says Dan Crowley, executive vice-president and F-35 programme general-manager. The Pratt & Whitney F135 engine and Rolls-Royce lift system have been installed.

F-35B final assembly
BF-1 in final assembly - red dust cap aft of cockpit covers lift fan     © Lockheed Martin

BF-1 will roll off the final assembly line at Fort Worth, Texas and move to the fuel barn to begin ground testing. Hover pit testing with the aircraft tied down is planned to begin early in 2008, leading up to a first flight scheduled for May. Flight testing will begin with conventional take-offs and landings and "build down" to vertical flights.

The conventional take-off and landing AA-1 returned to the air following a seven-month hiatus after its 19th test flight was cut short in May by a brief electric failure. Modifications, upgrades and a test-stand failure that required recertification of the F135 engine kept the aircraft on the ground.

Envelope expansion and flying qualities testing will now resume, Crowley says, with aerial refuelling qualification expected early in 2008. AA-1 is planned to fly to Edwards AFB, California, in the first quarter for airstart testing, its first deployment away from Lockheed's Fort Worth plant. "Envelope expansion will be slow and steady, consistent with [US Navy] practice," he says.

F-35 AA-1 flight small JSF CATBird flight small
F-35 AA-1 (left) and CATBird (right) return to flight           © Lockheed Martin

Shake-down flights of the CATBird followed outfitting of the modified Boeing 737-300 at Fort Worth. The aircraft has been fitted initially with the F-35's Northrop Grumman-supplied communication/navigation/identification (CNI) system as a first step towards integrated flight testing of the JSF's mission system.

"The first seven flights will be for CNI, then we will add sensors incrementally over 2008 until we begin integrated testing towards the end of the year," says Crowley. The CATBird was modified by BAE Systems in Mojave, California and flown to Fort Worth for installation of wiring harnesses, engineering workstations and avionics boxes.

The first flight of aircraft BF-1 will begin a ramp-up in JSF testing. "Of the 18 aircraft in system development and demonstration, we will deliver four in 2008 - two flight-test and two ground-test - and 14 in 2009," says Crowley. The flight-test programme is scheduled to continue to 2012.

The F135 engine in BF-1 at roll-out will be replaced before pit testing because of high-cycle fatigue concerns. "It's been useful for fit checks," he says. The lift fan will also be replaced, because of a "minor defect" in one of its counter-rotating fans. But Crowley is confident that propulsion system testing will support a May first flight.

Crowley says the remaining F-35 development aircraft "vary from on time to a couple of months behind". Each of the airframe sections arriving at the Fort Worth final-assembly line is "more complete, with less travelled work", he says.

Source: Flight Daily News