Optimization and Design for Heavy Lift Launch Vehicles

The simulation and evaluation of an orbital launch vehicle requires consideration of numerous factors. These factors include, but are not limited to the propulsion system, aerodynamic effects, rotation of the earth, oblateness, and gravity. A trajectory simulation that considers these different factors is generated by a code developed for this thesis titled Trajectories for Heavy-lift Evaluation and Optimization (THEO). THEO is a validated trajectory simulation code with the ability to model numerous launch configurations. THEO also has the capability to provide the means for an optimization objective. Optimization of a launch vehicle can be specified in terms of many different variables. For a heavy lift launch vehicle in this thesis, the goal of optimization is to minimize Gross Lift Off Weight (GLOW). THEO provides the capability to optimize by simulating hundreds of thousands of trajectories for a single configuration through the variation of preset independent variables. The sheer volume of these trajectories provides the means to locate configurations that minimize GLOW. Optimization can also be performed by determining the minimum amount of energy necessary to reach target burnout conditions. The energy requirements are then correlated to the propellant mass which can be used to estimate GLOW. This thesis first discusses the validation of THEO as a simulation program and the properties associated with accurately modeling a trajectory. It then relates how THEO and other developed tools can be utilized to determine a configuration that is optimized to minimize GLOW to orbit for adaptable payload sizes.