Tradeoff Analysis of Aerodynamic Wing Design for RLV

This chapter discusses optimization of the wing shape of flyback booster for a "two-stage-to-orbit" reusable launch vehicle considering four objectives. The objectives were to minimize the shift of aerodynamic center between supersonic and transonic conditions, transonic pitching moment and transonic drag coefficient, as well as to maximize subsonic lift coefficient. The three-dimensional Reynolds-averaged Navier-Stokes computation using the modified Spalart-Allmaras one-equation model was used in aerodynamic evaluation accounting for possible flow separations. Adaptive range multi-objective genetic algorithm was used for the study because tradeoff can be obtained using a smaller number of individuals than conventional multi-objective genetic algorithms. Consequently, four-objective optimization produced 102 nondominated solutions, which represent trade-off information among four objective functions. Self-organizing maps were used to analyze the nondominated solutions and visualize trade-offs and influence of design variables to the four objectives. These maps contoured by the four objective functions and design variables were found to visualize trade-offs and effects of each design variable.