Launch Vehicle Performance Enhancement Using Aerodynamic Assist

Abstract

A complete preliminary design model of a three-stage solid-fuel launch vehicle has been combined with a genetic algorithm to perform an optimization study with the goal to enhance performance using aerodynamic assist. Three studies have been completed which include improving the suborbital and orbital flights of a modern intercontinental ballistic missile and improving on the orbital flight of a generic threestage launch vehicle. The performance is enhanced by varying the geometric definition of the attached wing structure and the internal propellant geometry while the external geometry remains constant. Initial system weights and propellant mass fractions were found to decrease with the addition of the wing structure. Further enhancement involves a payload increase by 10% with a negligible increase in system weight, and a propellant mass decrease by 5.2% without impairing the flight performance. vi ACKNOWLEDGEMENTS The author would like to thank Dr. Roy Hartfield and Dr. John Burkhalter for their technical and professional guidance and support. The author also would like to thank Dr. Murray Anderson, the author of the 3.1 IMPROVE Genetic Algorithm, without which this thesis would not have been possible. The author would also like to thank his parents Harry and Leslie and sister Amanda for their support and encouragement, and his wife Nicole for all her patience and support provided throughout the graduate school process. vii

Optimization of an Aero Assisted Launch Vehicle

“…A non-intuitive observed is that the optimized vehicles apparently exhibit similar payload and fuel ratios for top, middle, and bottom stages respectively, despite the addition of wing structure. Perhaps a more compelling way to present the results relating to the enhancement of performance using aerodynamic assist is to consider the effective specific impulse as calculated using the rocket equation from dynamic, shown in Equation 4. The final calculations can be found in Table 5.…”

“…This computes to a reduction in weight of over 28%. Just as was the case with the suborbital vehicles, an analysis was performed to determine the effective propulsive specific impulse using the changes in velocities, the stage weight breakdown, and equations [1][2][3][4] defined earlier. Shown in Table 6 are the final results of this analysis for both payload configurations.…”

“…Using this general approach to the preliminary design, a substantial performance improvement for a Minotaur-type satellite launch vehicle has been obtained using preliminary design level tools and a genetic algorithm 3 . McDavid et al 4 showed how this study could be modified to include wings and how some improvement could be made by taking advantage of the lift production of the wings. This effort expands on that work by making use of a more comprehensive treatment of the aerodynamics and mechanics modeling as well as more in-depth analysis of the mechanics of aerodynamic assistance for launch vehicles.…”

A Method for Optimizing Launch Vehicle Aero-Assist Including Path Optimization

“…Similar optimization based trade studies have been used to improve the design for launch vehicles without using aerodynamic assist 3 and it has been shown that the addition of some aerodynamic surfaces can, in some cases improve performance even without trajectory optimization included except for launch angle. 4,5 This effort expands significantly on that work by incorporating a new path optimization approach based on solving the inverse problem for following paths proposed by an optimizer with the help of dynamic spline fitting 6 and by improving the fidelity of the vehicle modeling capability.…”