The Construction of a Postbuckled Carbon Fibre Wing Box

Abstract

A postbuckled carbon fibre structure requires special design considerations to avoid delamination failures. A practical design for a postbuckled wing box is presented. The design features incorporated have been proven in the author’s testing programme. This is leading to the testing of a full-scale wing box for an aerobatic light aircraft. Various means of improving the strength of skin/stiffener junctions are described, including the use of Kevlar stitching at this critical area.

A co-curing technique is used to form all the joints made directly to the skin surfaces. Tooling suitable for low volume production has been developed to form these joints. Final assembly of the structure is by adhesive bonding. Different configurations of joint are evaluated. A type of slotted joint is developed which uses features incorporated into the co-cured mouldings. This type ofjoint allows the structure to be assembled without the use of expensive clamping jigs.