Optimal ascent of a horus/sänger type space vehicle

For the rocket-powered winged second stage of Sanger called Horus, an investigation on optimal ascent trajectories is presented. It is shown that the lifting capability (together with thrust vector inclination due to angle of attack) is substantial for achieving an ascent in the lower region of flight path angles at separation. This is the region which is of particular practical interest. Furthermore, the additional control of thrust vector angle is considered. An interesting characteristic of optimal ascent trajectories concerns a zero-thrust phase after separation instead of applying immediately full thrust. The conditions for the existence of such unpowered flight phases are investigated. Furthermore, the effect of a longitudinal acceleration constraint is considered. It is shown whether or not consequences of practical significance may result. Two optimization methods have been applied. One technique is based on the method of multiple shooting. The other technique utilizes the parameterization of the control vector function.