The Boeing Joint Strike Fighter (JSF) programme team claims to have identified a range of installed thrust improvement and weight reduction options for the US Marine Corps and Royal Navy version of the X-32 demonstrator. The team says the improvements more than address the projected payload performance shortfall in the aircraft, being built in competition with a rival Lockheed Martin design.

Boeing JSF weapon system director Dennis Muilenburg said at this year's US Navy League Sea-Air-Space Exposition in Washington on 29-31 March, that the company has found enough areas in which to either cut weight or improve powerplant efficiency to bridge the gap four times over. He declined to quantify the shortfall.

Boeing says that its current preferred weapon system concept (PWSC) design configuration meets 95% of the requirement laid down by the latest joint interim requirements document, JIRD 3, issued by the US Department of Defense. The short take-off/vertical landing (STOVL) version, however, does not yet meet the 1,810kg (4,000lb) bringback load requirement.

The list of remedies encompasses improvements to the PWSC's Pratt & Whitney F119 power plants inlet and lift performance and/or airframe and system weight reductions. Muilenburg says savings could be achieved in the JSF landing gear, flight control systems, and enhanced integrated avionics suite, where there are major weight opportunities.

These STOVL performance refinements, along with the selection of a gun, will need to be settled by the time Boeing submits its final PWSC design in 2000. The JSF programme office is due to release a draft joint operation requirement document in April, and a final version by the end of the year.

JIRD 3 stipulates a fixed internal gun for the US air force's conventional take-off and landing version and study of a missionised gun module for the other aircraft carrier and STOVL derivatives. Boeing says that it is leaning towards the Mauser 27mm system installed in the aircraft's forebody and is looking at a range of internal weapon bay and external hardpoint mounting options for the naval and Marine versions.

Boeing meanwhile claims to be ahead of schedule and 50% below its targeted cost reduction for the construction of two JSF X-32A /B concept demonstrators. Boeing's St Louis-based Phantom works has delivered its first X-32A forebody to Palmdale, where it was scheduled to have been mated with the midbody by the end of last week.

Source: Flight International