2232. Determination of the Manager’s Reserve Guideline for the Space Shuttle Xo Center of Gravity

Paper

Abstract

The space shuttle’s Xo center of gravity (CG) requires a major consideration when designing the descent phase of a mission. The space shuttle’s forward Xo CG Limit during descent at Mach 3.5 is 1079.0” (27.4066 m) for Return To Launch Site (RTLS) and 1076.7” (27.34818 m) for Nominal, Transoceanic Abort Landing (TAL), Abort Once Around (AOA), and Non-Deploy scenarios. Recently, forward Xo CG shifts a few months before launch have required late ‘fixes” to be made. These ”fixes” often require rework, reverification, and/or overtime which increase costs and may take available resources away from other missions. Current payload manifesting at various milestones have made the flights Xo CG at or very near the forward limit. To aid managers when manifesting additional items on a flight, historical and current flight mass properties data were analyzed to determine if a guideline could be established. This guideline would be based upon potential impacts of unknowns following a particular milestone. The establishment of this guideline should provide managers an adequate tool for minimizing late ‘fixes” while maximizing the space shuttle’s carrying capabilities. During the latter stages of a mission’s flow, the Xo CG was usually found to move forward. The last chance to manifest payloads occurs at the Flight Planning and Stowage Review (FPSR). This meeting precedes a critical milestone for flight design. A 0.5” (0.0127 m) margin at this time was determined to be adequate for most flights while allowing maximum manifesting capability. On the average, primary payload mixes for future flights are projected to have a more forward combined Xo CG than past flights; thus, this guideline will become an important tool for managing a flight and reducing program costs.