Navy aircraft managers refine requirements in post-Iraq era

Sea Power, Jun 2003 by Burgess, Richard R

The F-35A-designed for the Air Force and the only variant to be armed with an internal gun-is being altered so that the gun boresight is optimized for air-to-ground rather than air-to-air combat.

The upper fuselage of the F-35B short-takeoff/vertical-landing (STOVL) version of the JSF is being redesigned to reduce drag. Larger exhaust-inlet doors and roll posts are being installed, and the bi-fold lift-fan doors have been replaced by an aft-hinged door.

The F-35C carrier-based version has been redesigned with a larger wing, modified fairings, and an improved fairing for the main landing gear.

The weight of the STOVL version was two percent greater than specified in the design target for the PDR, said Tom Burbage, executive vice president and general manager of the F-35 program at Lockheed Martin Aeronautics Company. Design engineers have been working to meet the weight goal.

"There is great value to having a STOVL variant in the mix," Burbage said, pointing out that the other two variants also would benefit significantly by the weight reduction efforts. He said that the design team would not be "shaving anything off the airplane," but removing things "that were not efficient."

JSF team PDRs also have been completed on the Pratt & Whitney F135 engine and GE Aircraft Engines' F136 engine for the F-35.

The first production F135 goes into engine test in September 2003. The first F136-interchangeable with the F135-is slated for production approximately two years later.

Rolls-Royce has redesigned the clutch for the engine's lift fan to make it more rugged.

Lockheed Martin has increased the number of employees engaged in F-35 work tenfold-from 400 to more than 4,000-since the company was selected to design and build the JSF. The company's plant in Fort Worth, Texas, will build the aircraft's wing and forward fuselage, and will perform the final assembly of the F-35. The company's plant in Palmdale, Calif., will fabricate the low-observable edges of the aircraft's airfoils. The mid-body fuselage and aft fuselage will be built by Northrop Grumman at its facilities in Palmdale and El Segundo, Calif., respectively. BAE systems will build the aircraft's vertical stabilizers and engine exhausts at its plant in Salmesbury, England.

The JSF is scheduled for Critical Design Review in April 2004. The first flight of the aircraft is slated for the fall of 2005.

Lockheed Martin expects to build more than 3,000 JSFs for the United States and United Kingdom at a rate of one F-35 per day when the production reaches its anticipated output rate.

Unmanned Combat Aerial Vehicle

The Air Force and Navy unmanned combat aerial vehicle (UCAV) programs are moving closer to becoming a joint program, and the emerging UCAV designs are indicative of an emerging service commonality.

Boeing currently is under contract with the Air Force and the Defense Advanced Research Projects Agency (DARPA) to develop the X-45 UCAV, and Northrop Grumman is under contract from the Navy and DARPA to develop the X-47 UCAV for the Navy as the UCAV-N program. DARPA has asked Boeing to modify its current X-45B UCAV design, however, to meet the Air Force's need for greater range and loitering capability and the Navy's objectives for its UCAV-N demonstration program.