New method for Shuttle Orbiter thermal analysis

Abstract

A new, simplified, approximate method of on-orbit transient thermal analysis of complex operational space vehicles in varying environmental conditions is described. When applied to the Space Shuttle Orbiter simulation, the standard deviation of error in results compared with flight data for over 50 missions is typically between 5 and 10°F. The method requires first running detailed orbiter thermal mathematical models for a steady-state solution in a systematized variety of on-orbit Earth-sun orientations. These steady-state temperatures form a database that is loaded and permanently stored in a personal-computer-based program package. An exponential extrapolation method derived from a classical simplified energy balance and using empirically derived time constants is applied to convert from the steady-state temperature to the actual transient response. Now in use routinely for thermal analysis of the Space Shuttle Orbiter, the method has reduced the days of engineering manpower and hours of mainframe computer usage previously required to a simple, painless, and short session on a personal computer. The results, although approximate and sometimes limited in certain special situations, have been found generally to yield excellent agreement with flight data.