Composite Wing Substructure Technology on the AV-8B Advanced Aircraft

Abstract

Composite structure has been used extensively in the wing of the AV-8B as one of the technological improvements to increase the operational effectiveness of this second generation V/STOL aircraft. In addition to reducing the structural weight the use of composite materials has permitted unconstrained optimization of the aerodynamic shape to enhance performance. The torque box consists of one-piece graphite/epoxy monolithic skins measuring 28 feet from tip to tip and a multi-spar graphite/epoxy substructure with sinewave webs. There are 84 composite substructure parts, the largest being 12 feet long, tapering from 14.5 inches to 6.5 inches in height. Metal fittings are used at all concentrated load points such as flap and aileron hinges and pylon, outrigger gear and wing-to-fuselage attachments. The innovative design and manufacturing concepts were first made concrete in test articles which were fabricated and tested prior to the final wing design to achieve a composite wing that meets all NAVAIR requirements. This paper discusses the design development of the torque box composite substructure, including considerations of sinewave size and shape, load carrying considerations for the webs and flanges; modifications required for the attachment of ribs, fuel lines, hydraulic and control rods; fuel flow consideration; corrosion protection for the aluminum parts; and the development of tooling and fabrication methods, including the assembly of parts bv mechanical fasteners.

The torque box consists of one-piece graphite/epoxy monolithic skins measuring 28 feet from tip to tip and a multi-spar graphite/epoxy substructure with sinewave webs. There are 84 composite substructure parts, the largest being 12 feet long, tapering from 14.5 inches to 6.5 inches in height. Metal fittings are used at all concentrated load points such as flap and aileron hinges and pylon, outrigger gear and wing-to-fuselage attachments.

The innovative design and manufacturing concepts were first made concrete in test articles which were fabricated and tested prior to the final wing design to achieve a composite wing that meets all NAVAIR requirements.

This paper discusses the design development of the torque box composite substructure, including considerations of sinewave size and shape, load carrying considerations for the webs and flanges; modifications required for the attachment of ribs, fuel lines, hydraulic and control rods; fuel flow consideration; corrosion protection for the aluminum parts; and the development of tooling and fabrication methods, including the assembly of parts by mechanical fasteners.