Design Development of Unitized Titanium Structure

Abstract

Traditional airframe primary structure is fabricated from wrought product forms that are transformed by machining, forming, and joining into structural components. These individual parts are assembled together by fasteners to create the airframe. Significant cost and cycle-time savings can be achieved by switching from multipiece builtup assembly to a single-piece net shape casting. The reduction in number of discrete parts provides a significant reduction in both direct and indirect costs. In particular, the inherent low material costs and excellent producibility characteristics of cast metallic parts may provide a significant contribution to the goal to reduce acquisition costs. Under the program reported herein, and in conjunction with a casting vendor, prototype titanium (Ti-6Al-4V) cast airframe components were designed and fabricated. The typical overall dimensions of each casting are 50 inches×40 inches×30 inches, and weigh approximately 190 pounds per casting. The castings were modeled on generic aircraft fuselage structure, that incorporated smooth inner moldline surface and integral webs and keels, capped by a T-element, web stiffeners, access holes, and other detail features. Multiple castings are joined to create the airframe structure. A rapid prototyping method was utilized to create the pattern, which eliminated the requirement for expensive metal tooling. The prototype castings successfully demonstrated the producibility of this generic airframe structure.