Pratt & Whitney is preparing five more ground-test engines to support seven units already participating in the F135 engine development and demonstration program for the F-35 Joint Strike Fighter (JSF). Two of the five will be used to qualify propulsion-system configuration ahead of planned delivery of the first-flight engine to Lockheed Martin by year’s end. More than 3,000 hours of development testing has been completed (and a further 2,000 hours are planned before next year), with overall results said to have met thrust requirements.

Assembly of the first-flight engine will begin in August, with the aircraft scheduled to fly a year later. Production deliveries are slated to start in 2009, three years ahead of operational service. Development testing was preceded by 3,500 hours of ground running and 200 hours of flight in connection with JSF concept demonstration tests for Lockheed Martin and Boeing, including work for the F/A-22 Raptor’s F119 engine from which the F135 is derived.

Three F135s have been delivered in conventional takeoff and landing/carrier variant configuration, and three in short takeoff and vertical-landing mode. Accelerated mission testing has begun with both variants, and sea-level and altitude testing are also under way.