Optimal control of ascent trajectories and rotary dynamics for wingless orbital stages

Abstract

For a rocket type orbital stage of a space transportation system with an airbreathing first stage, an investigation on ascent performance is presented. Particular emphasis is given to the lifting capability of the wingless orbital stage because of its decisive influence on ascent performance. A rocket type orbital stage without a lifting capability can perform an ascent to an orbit only when the flight path angle is rather large for a separation condition in hypersonic flight at high altitude. However, rocket type vehicles without a wing have a limited lifting capability which enables the vehicle to achieve an ascent to an orbit even if the separation flight path inclination is small. It is shown how this capability can be utilized in an optimum manner. This concerns the optimal control of lift, thrust setting and thrust vector angle. In addition to point mass dynamics, a model including pitching moment balancing and rotary dynamics is also investigated. It is shown which effects for ascent control and performance result.