Advanced grid stiffened structures for the next generation of launch vehicles

Although the necessity of using composite materials in the next generation of launch vehicles has become widely accepted, the specific structural type (monocoque, sandwich, skin-stringer, etc.) has yet to be determined. One possible candidate is the Advanced Grid Stiffened (AGS) structure, a rib-skin configuration evolved from early isogrid stiffening concepts. AGS structures show great promise for satisfying increased reliability and reduced cost requirements due to their adaptability to automated manufacturing. They also lend themselves to use in operational environments, due to their high strength, resistance to moisture absorption, and damage tolerance. Recent research has focused on the manufacture and design of AGS structures, specifically focusing on the potential for automated manufacture. In early 1997, the first composite AGS launch vehicle component, a payload shroud fabricated using fully automated techniques, will be flown on a suborbital flight. The manufacturing and tooling techniques developed as part of this program represent a significant step toward the goal of affordable launch-vehicle structures. An overview of AGS structures is presented along with a description of their current manufacturing 'state of the art.' A synopsis of the AGS payload shroud program is also presented.