Friction stir welded wingtip torque box

Abstract

Provided are wingtip torque boxes and methods of fabricating such boxes using friction stir welding. Specifically, a wingtip torque box may be formed by friction stir welding two monolithic clamshells along their respective spars thereby forming a new monolithic structure. Use of the friction stir welding and monolithic clamshells simplifies the overall fabrication process and yields a robust wingtip torque box that can be bolted on or otherwise attached to an aircraft wing. The wingtip torque box may include internal grid stiffeners and/or external stiffeners that may be also monolithic with other components of the box. For example, the stiffeners may be machined in spars or skin portions of the clamshells during fabrication of clamshells. The wingtip torque box may have a continuous cavity extending between the ends and, in some embodiments, between spars of the box and providing access for performing various operations inside the box.