A Concept and Its Aerodynamic Design of a Sub-Orbital Reusable Rocket

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A b aseline system of a sub -orbital reusable rocket and its aerodynamic studies conducted in ISAS (Institute of Space and Astronautical Science) / JAXA (Japan Aerospace Exploration Agency) are presented. The vehicle adopts a vertical take -off and vertical land ing (VTVL) system to minimize ground support equipments (GSE) and turn -around time. An integrated propulsion system which consists of four 2 -ton -class liquid -hydrogen / liquid -oxygen (LH2/LOX) expander cycle engines, a gaseous -hydrogen / gaseous -oxygen (GH 2/GOX) reaction control system (RCS) and an auxiliary power unit (APU) are introduced in order to simplify ground operations and reduce turn -around time. The vehicle is designed to meet the requirements of carrying 100kg payload on a round trip to 120km an d repeating the mission within 24 hours. Aerodynamic design considerations are made on the vehicle. The airframe shape is basically axisymmetric; wings are excluded or minimum. The pros and cons of t wo way s of descent, i .e., nose -forward and base -forward d escents , are discussed according to the vehicle system requirements. Since in the base -forward descent the downrange requirement is not met, the nose -forward descent is adopted. The airframe shape is optimized combined with the aerodynamic force calculatio n so that the drag is minimum in ascent and the lift -drag ratio is maximum in descent. The ‘turn -over ’ maneuver, i.e., the change from the nose -forward descent attitude to the base -down landing attitude, is required for the nose -forward descent system. T he interaction between engine plume s and a free -stream become important for design of an attitude control system in the phase of deceleration using engines , and the interaction between an engine jet plume and a ground become important for design of a thermal protection system for landing gears just before the touch -down as well as the take -off.