Post-flight evaluation of the guidance and control for D-SEND#2 2nd drop test

This paper is focused on the post-flight evaluation of the guidance and control for D-SEND#2 2nd drop test successfully conducted in 2015 at Esrange Space Center in Sweden. The guidance law can cope with varying separation conditions and features real-time trajectory prediction to adapt various modelling errors and uncertainties. Hierarchy-structured dynamic inversion is applied to the attitude control to accommodate a broad flight envelope. The post-flight evaluation results based on the telemetry data conclude that both the flight requirements and the mission requirements are satisfied and that the guidance and control law worked accurately as designed. However, they also conclude that there was a significant amount of error especially in the drag coefficient. The estimated aerodynamic errors and reconstructed atmospheric model based on the radiosonde data are then incorporated into a post-flight closed-loop simulation and the actual flight behavior has been to a large extent reproduced.