The Manufacture of Composite Structures Using Closed Cavity Tooling and Internal Bagging

The manufacturing process to be described involves the bonded assembly of a graphite wing component. Matched graphite bond forms are used to control the upper and lower outside contours. Precured graphite spar straps, webs and clips supported by sacrificial high density polystyrene formed mandrels encased in formed tuffel bags produce the cocured three celled bonded assembly. The graphite composite structure is approximately three feet wide, twelve feet long with a maximum thickness of six inches. The composite assembly is composed of cocured skins and inner wraps supported laterally by two precured spar straps. Vertical support is achieved by the use of precured webs and clips located in the forward third and aft third of the assembly. The webs and clips form three lateral cells. Precured spar straps are polar wound and compacted on the McClean-Anderson pin winder. Wound graphite straps are precured in a contoured compact and cure tools The structure has two spar straps, one upper and one lower, to carry the loads of the pivoting canard wing assembly. The open cell approach using formed polystyrene mandrels placed in tubular tuffel bags give shape, stability and location for lay up. Tuffel bags are held open by end plate manifolds to supply bonding pressure in the autoclave cycle. The high density styrofoam collapses during the cure cycle and is easily removed from the structural cell with the removal of the rubber bag. After bond the assembly will be removed from the bond cavity, trimmed and inspected.