Lockheed Martin has unveiled detailed configurations of its three planned Joint Strike Aircraft (JSF) X-35A/B demonstrator derivatives, as designs are fined-tuned and attention begins to focus on aircraft systems and cost control.

"We're now at the point where we know we have the right aerodynamic configuration and we're starting to shift our emphasis from this to our mission systems, lethality, supportability and affordability," says Harry Blot, JSF deputy programme manager.

Lockheed Martin's final 230-3 designated configuration provides for a common conventional take-off and landing (CTOL) and short take-off/vertical landing (STOVL) aerodynamic planform and a slightly enlarged aircraft carrier (CV) variant. All three versions will share the same 15.45m (51ft)-long fuselage.

The US Air Force's 230-3A and US Marine Corps/Royal Navy -3B versions incorporate a common 38.27m2 (412ft2) wing, while the wing of the US Navy's -3C configuration will be increased in area to 55.7m2.

The- 3C will also have ailerons, in addition to flaperons, and a 20% enlarged horizontal stabiliser and tail for lift and slow approach speed control. The 11m wingspan on the RN JSF will incorporate 75cm folding wingtips to fit on the RN Invincible-class carrier lifts. The USN version will have larger folding wingtips, but these will hinge at the same 9m point.

Lockheed Martin has designed the X-35's twin curved air inlets to provide complete engine signature line of sight blockage, feeding air via a divertless duct tested on an F-16 under an earlier "black" programme. "We have designed an intake that has already been to Mach 2 without any moving parts," Blot says .

The X-35B's Pratt & Whitney F119-611S engine will provide 18,000lb (80kN) of ambient thrust in the hover through the forward-shaft-driven lift fan, 15,000lb the rear three- bearing main nozzle and 4,000lb through the two side roll-control ducts. The CTOL and CV demonstrator will be fitted with an additional fuel tank in place of the lift fan.

The 230-3B and 3C configurations incorporate a retractable in-flight refuelling probe, while the USAF's -3A will have a receptacle for use with fixed boom tankers.

Source: Flight International