The new F135 short take-off / vertical landing (STOVL) variant propulsion system designed by Pratt & Whitney more than reached expectations in a recent vertical thrust performance test.

The system’s better-than-expected performance now means the fifth-generation fighter engine can provide F-35 Lightning II STOVL aircraft with more vertical power than needed.

The engine demonstrated an additional 550lb of vertical thrust over the test requirement of 40,550lb.

Pratt & Whitney F135/F119 programme’s vice president Warren Boley said it means the vertical landing and short take-off performance for for STOVL customers can be promised a good margin .

The test measured all the operations associated with the STOVL propulsion system for vertical flight. It included engine auxiliary inlet, LiftFan inlet, LiftFan exit, roll posts, doors and vector engine thrust.

The F135 STOVL propulsion system includes Rolls-Royce LiftSystem components apart from the Pratt & Whitney main engine.

After this final series of ground tests, airborne STOVL testing will begin.