Innovative Method for Return to the Launch Site of Reusable Winged Stages

Kurzfassung

This paper proposes a new, and different approach for return to the launch site of non-SSTO reusable space transportation vehicles. The winged reusable stages are to be caught in the air, and towed back to their launch site without any necessity of an own propulsion system. This so called in-air-capturing method (patend pending) is initiated by large cargo transports, ffering sufficient thrust capability to tow a winged launcher stage with restrained lift to drag ratio. Technical requirements of the tow-aircraft indicate, that (depending on the stage's size) an Airbus A-34o or B-747-class jet offers good thrust margins. The performance gain by the advanced capturing method shows a possible increase in delivered payload between 15% and 25%, assuming the same structural technology level of the stages. Alternatively, the size of a reusable system can be significantly reduced compared to the standard approach, without any loss in payload mass. The paper presents a detailed description of the proposed method, giving data of numerical simulations regarding the nominal mission. A comparative analysis, looking also at conventional systems quantifies the advantages. The second part of the paper proofs the viability of the proposed in-air-capturing method by regarding its off-design performance.Assuming different perturbations of the normal flight, including a change in atmospheric wind or slightly different stage-separation conditions. Analysis shows the flight dynamic potential of the descending vehicle to dissipate energy to be quite comfortable.