Research on bi-directional flying wing space shuttle configuration

The inconsistency between high-lift requirement at taking off and high lift-drag ratio requirement at supersonic/hypersonic flying often confuses aerospace shuttle designers. Bi-directional flying wing concept consists of a symmetric diamond planform. This wing flows with a high aspect ratio shape at subsonic speed, while changes its flying mode by rotating the aircraft 90° around vertical axis. It finally flows with a low aspect ratio shape at hypersonic speed. This concept is considered as a new way to overcome the design conflict between subsonic and hypersonic flight. By using the new concept, this paper constructed an aerospace shuttle. The CFD result shows that, compared with German TSTO vehicle, i.e., Sanger, the new concept aircraft has a 30%-50% higher lift-to-drag ratio at subsonic speed, reaching 16 while maintains a high lift-to-drag ratio at hypersonic speed, reaching 4. It has been indicated that bi-directional flying wing configuration is a potential option for space flight. Furthermore, three main problems have been pointed out in designing this new concept vehicle. These problems are longitudinal stability issue at subsonic speed, conversion disorders in changing flying model, and difficulties in coupling airframe and engine design, respectively. For each problem, one or more applicable solutions were proposed. Particularly, a new flying conversion mode was indicated by installing two asymmetrical vertical fins at the tail the fuselage to provide enough control moment and improve lateral stability for the aircraft. In addition, a new power plant, i.e., the installment of individual orthogonal engines in different direction was proposed to reduce the requirements of combined power. These means may contribute to the realization of the bi-directional flying wing concept.