Launch Vehicle Propulsion Design with Multiple Selection Criteria

Abstract

An analytical optimization and evaluation approach is presented for sizing a liquid hydrogen/liquid oxygen, single-stage-to-orbit system. The approach uses a unique merging of historical data for weight relationships, Monte Carlo simulations for uncertainty analysis, technology factors, thermochemical analysis, and genetic algorithm solvers for concept optimization. The method models and optimizes engine chamber pressure, area ratio, and oxidizer/fuel ratio to determine the best vehicle design based on seven separate cost/weight figures of merit Model results show that a 53% increase in design, development, test, and evaluation cost results in a 67% reduction in gross liftoff weight. The uncertainty range for the design, development, test, and evaluation costs is shown to be from -45 to +76% of the mean value for the 95th percentile uncertainty case. The oxidizer/fuel ratio has a significant impact on the overall weight of the vehicle and vehicle components due to the large percentage of the gross liftoff weight that is dedicated to propellants. Other results show the effects of propulsion parameters, technology factors, and cost factors on weight and cost under different overall design constraints.