Composite wing structures aerostructure manufacturing offering

The Composite wing structures is an aerostructure manufacturing offering from GKN Aerospace with aerospace-grade quality and in-production availability. Composite wing structures are carbon-fibre aerostructures manufactured by GKN Aerospace for commercial and military aircraft, and the offering covers primary wing parts such as spars, fixed trailing edges, flaps and ribs. As a supplier of aerostructure manufacturing, GKN Aerospace takes a structure from design through tooling and production to delivery of finished assemblies that the airframer integrates into the wing box.

The spar is the best documented part of this work. A wing spar is a long C-shaped or I-shaped member that runs from root to tip and carries the bending loads produced by aerodynamic forces, and it is usually tapered and swept to follow the wing contour. GKN Aerospace has supplied composite wing spars and fixed trailing-edge assemblies for the A330, A400M and A350 aircraft. For the A350 the rear spar is built in sections of just over 11 m, laid up by automated fibre placement of carbon prepreg on C-shaped mandrels, cured in an autoclave and joined with carbon-fibre plates.

A second route is resin transfer moulding. For an Airbus wing technology demonstrator, GKN Aerospace made a trailing-edge spar of 17 m in a single piece with a C-shaped section and two angle changes to follow the wing sweep. It uses a two-ply carbon non-crimp fabric infused with an epoxy resin system, the fabric is sheared rather than cut and darted to avoid wrinkling, and the part is moulded in one shot with no joints. Test spars showed porosity below 2 percent. Dry fibre infusion removes about a third of the production steps compared with pre-impregnated material and is aimed at high-rate automated manufacture.

For ribs, GKN Aerospace developed a carbon-fibre thermoplastic design that is mechanically equivalent to an aluminium rib. The demonstration rib is 90 cm long and 24 cm tall, with a 7 mm web, an 8 mm flange and 3 mm stiffening elements joined by the maker's butt-joint technology. It is consolidated in a single step outside an autoclave in a modular press with a cycle time of 45 minutes. A composite rib in a composite wing avoids the difference in thermal expansion and the corrosion issues of metal ribs, and reduces weight.

Typical customers are airframers building large single-aisle and twin-aisle airliners and transport aircraft. GKN Aerospace also works with advanced air mobility manufacturers whose one-piece wing designs benefit from a one-piece composite spar that can be produced quickly and efficiently.