Ascent optimization for a heavy space launcher

This paper exposes work to optimize the ascent trajectory of a multistage space launcher. Motivated by well-known singular arc effects as in the case of the Goddard rocket, we investigate whether the payload of the launcher can be enhanced by means of a variable thrust during the first phase of the flight. Due to the high complexity and numerical sensitivity of the multistage problem, we use constructive methods for initialization and handling input constraints in optimal control to compute the ascent trajectories. Based on realistic numerical values for key design parameters and flight dynamics, we conclude that the computed trajectories are in fact full thrust.