DYNAMIC MODELLING AND CONTROL OF AN AERODYNAMICALLY CONTROLLED CAPTURING DEVICE FOR ‘IN-AIR-CAPTURING’ OF A REUSABLE LAUNCH VEHICLE

Abstract

The renewed interest in reusable launch vehicles has fueled the development of many advanced space transportation concepts. An interesting method for recovering rocket stages called ’In-AirCapturing’, has been patented by DLR. The winged stages are captured mid-flight and towed back to the landing site by an aircraft, eliminating the need for an additional propulsion system. A critical procedure in the capturing process involves an aerodynamically controlled capturing device attached by a rope to the towing aircraft, performing an autonomous rendezvous maneuver with the launch vehicle. In this paper, the complex dynamics associated with this phase are modelled and examined. This includes the aerodynamics of the capturing device, external disturbances like the turbulent wake of the aircraft and the flexible dynamics associated with the rope. These effects are combined into a multidisciplinary framework and a preliminary control system is proposed. The final open-loop simulation results provide valuable information about the stability and controllability of the system, which will be used for advanced control design in future work.