CONSTRUCTION OF the first composite wing skin for the Lockheed/Boeing F-22 fighter has begun at Boeing, marking the start of major-component manufacturing at the Seattle-based Defense and Space Group.
Boeing is charged with 32.5% of the F-22 work, with primary responsibility for the wing, aft fuselage, radar, 757 flying laboratory and the avionics integration laboratory (AIL). It also handles power supply, training, life support, fire protection, system test and the arresting gear.
"We are well into the tooling now," says Boeing F-22 programme manager, Frank Statkus. "We have started laying up the first upper wing-skin panel for air vehicle one, using automated tape layers," he says.
The primary composite used for the skin is Cytec bismaleimide, which is attached to lightweight "sine-wave" spars produced through resin-transfer moulding (RTM) techniques.
The first wing "will be on dock at Lockheed around mid-1996", with completion of the Boeing-developed aft-fuselage section expected in around April 1996, adds Statkus. Boeing originally planned an all-composite wing sub-structure, but has been forced to replace every third RTM spar with a more conventional titanium-built unit to meet revised tolerance levels to ballistic weapon damage.
Added to corrective actions taken to rectify the radar cross-section shortfall, the extra material has inevitably increased the overall weight of the F-22. The US Air Force recently approved an approximate weight growth of 420kg, plus almost 210kg of potential weight growth. Avionics work is also accelerating.