Mission performance of a spacecraft or launch vehicle is realized by insuring the most efficient transfer of impulse from the given boost system of the spacecraft. This goal is achieved by developing a simulation, which determines the optimal boost trajectory, with due consideration of the constraints imposed by the vehicle design. The trajectory simulation considers nonrotating spherical earth model and includes the effects of aerodynamic forces. The optimization problem is to maximize the final stage burnout velocity with prescribed flight path angle and height as terminal boundary conditions, for the specified boosters and payload. The angle of attack (α) is used as a control variable. Inequality constraint of product of angle of attack and dynamic pressure (αq) suitable for satisfying certain practical vehicle design are introduced. The indirect multiple shooting method is used to solve this problem, which determines the optimal time history control variable α.