Optimization of a Space Transportation System Including Design Sensitivities

摘要

A new method for the performance rating of a space transportation system is presented. The method combines a commonly used quality criterion, the so-called growth factor, with a penalty function that penalizes high sensitivities with respect to inaccuracies in the employed physical computation models. The method is applied to a space transportation system with horizontal takeoff and landing, an air-breathing first stage, and a rocket-propelled second stage. Using a multimembered evolution strategy, an optimization of the lower stage propulsion system is performed with and without considering design sensitivities. The results show that very critical situations can arise if the sensitivity to inaccuracies in the physical models is neglected. Furthermore, remarkable reductions of the design sensitivity by more than an order of magnitude are achievable with only moderate losses in the total system performance.