STOVL F-35B Ready To Begin Hover Pit Tests

Feb 17, 2009
By Graham Warwick



The first short takeoff and vertical landing (STOVL) F-35 Joint Strike Fighter could begin powered-lift testing on the hover pit at Lockheed Martin’s Fort Worth, Texas, plant as early as this week.

This will begin perhaps the most critical phase of testing for the F-35 program. About a month of hover-pit testing is planned before the first F-35B, aircraft BF-1, returns to the air to begin STOVL flight testing, says J.D. McFarlan, F-35 air vehicle development team lead.

This will build up to the first full vertical landing, expected to be performed at Naval Air Station Patuxent River, Md., in June or July and a key milestone for the program.

Hover pit tests will check performance and operation of the propulsion system up to full vertical thrust. In powered-lift mode the forward shaft-driven lift fan is engaged, the rear three-bearing nozzle swivels down and roll posts in the wing open.

BF-1 will be tied down over the open pit to measure forces and moments generated by the propulsion system during manual and automatic conversions between conventional and STOVL modes. Later the pit will be covered with steel plates to allow measurement of the ground environment and inlet temperatures and pressures during a vertical landing, McFarlan says.

Pit tests also will allow Lockheed Martin to measure the installed thrust of the Pratt & Whitney F135 engine and Rolls-Royce lift fan. This is key to confirming that the F-35B will achieve its STOVL performance objectives. McFarlan says the company is confident of achieving a minimum 40,550 pounds of vertical thrust, enough to enable the F-35B to meet its requirements.

Photo: Lockheed Martin