No abstract

In this paper, the research within the Horizon 2020-funded project FALCon on the innovative “In-Air Capturing” (IAC) method is presented. This recovery method for reusable rocket stages involves capture of a winged launcher stage with an aircraft in a gliding flight at subsonic velocity. Hence, the IAC procedure involves multiple vehicles interacting in a highly dynamic and complex environment, which requires detailed investigation before being used in a future full-scale setup. First, this paper gives an overview of the implications of using the IAC method on launcher system design. Second, the subscale flight testing with unmanned aerial systems (UASs) is explained. An analysis of all full-scale systems involved is also conducted, including the towing aircraft, an aerodynamically controlled capturing device that is connected via a rope to the aircraft, and the RLV stage. CFD simulations are conducted to understand the implications of the flow field around the vehicles and their impact on the IAC maneuver. Next, some full-scale trajectory simulations for different maneuvers involved in IAC are produced. The trajectory is also evaluated for subscale flight simulations, wherein the data acquired during flight tests is used. Finally, the progress and potential future outlook for this recovery method are described.

The recent success of reusable launchers has become a driving force for sustainable launch technologies. An innovative approach proposed by DLR, involves winged rocket stages captured mid air and towed back to the launch site by an aircraft. This recovery concept known as ‘In-Air Capturing (IAC)’, shows potential for substantial cost reduction, when compared to existing return modes. In the light of the Horizon 2020 project FALCon, full-scale simulations and sub-scale flight testing were carried out for further development of the technology. The paper summarizes the full-scale studies performed within FALCon. The full-scale test cases are introduced and the simulation framework for analysis of trajectories is presented. Then, the IAC maneuver is analyzed through trajectory simulations. Major external disturbances coming from the wake of the aircraft and flexibility of the rope connecting the rocket stage to the aircraft (after capture) are also addressed.