The Lockheed Martin F-35 Joint Strike Fighter has returned to flight with a 55min test sortie on 7 December. And, just over an hour after the aircraft landed back on the Fort Worth, Texas runway, Lockheed launched the F-35 avionics testbed - the CATBird - on a 2h check flight.

The first F-35, aircraft AA-1, last flew in May, when a brief electrical failure cut short the aircraft's 19th test sortie. The maiden flight was in December 2006.

The 20th flight, flown by F-35 chief test pilot Jon Beesley, tested engine performance and aircraft handling qualities up to 20,000ft in preparation for upcoming air refuelling flights.

F-35 20th flight TO
                                                                                                         © Lockheed Martin

Lockheed says Beesley executed a military-power take-off, ran the engine at various power settings, checked flying qualities at 6,000ft, 17.500ft and 20,000ft and performed a fuel-dump test at 250kt.

Further tests planned for AA-1 "include refuelling from an airborne tanker in the short term and supersonic flights next year", says Dan Crowley, executive vice-president and F-35 programme general manager.

The first short take-off and vertical landing F-35B is to roll off the assembly line at Fort Worth on 18 December and is scheduled to fly in May 2008. "By the end of 2008, we expect to have at least three F-35s in the air and numerous arcraft on the assembly line," he says.

F-35 CATBird TO small
                                                                                                     © Lockheed Martin

The CATBird, a highly modified Boeing 737-300, made its first functional check flight following installation of the F-35's communication-navigation-identification (CNI) system. The aircraft was modified by BAE Systems in California and flown to Fort Worth for final outfitting.

CATBird flights with the CNI system operating will begin airborne testing of the F-35's mission-systems suite. The active electronically scanned array radar, electro-optical distributed aperture system and electro-optical targeting system will be added later.

The CATBird will allow the fully integrated JSF avionics suite to be flight tested before the first mission-systems-equipped F-35 flies in 2009, says Lockheed.