This paper reports the findings of a conceptual launch vehicle design study performed by members of the Space Systems Design Laboratory at Georgia Tech. Hyperion is a conceptual design for an advanced reusable launch vehicle in the Vision Vehicle class. It is a horizontal takeoff, horizontal landing single-stageto-orbit (SSTO) vehicle utilizing LOX/LH2 ejector scramjet rocket-based combined cycle (RBCC) propulsion. Hyperion is designed to deliver 20,000 lb. to low earth orbit from Kennedy Space Center. Gross weight is estimated to be 800,700 lb. and dry weight is estimated to be 123,250 lb. for this mission. Preliminary analysis suggests that, with sufficient launch traffic, Hyperion recurring launch costs will be under $200 per lb. of payload delivered to low earth orbit. However, non-recurring costs including development cost and acquisition of three airframes, is expected to be nearly $10.7B. The internal rate of return is only expected to be 8.24%. Details of the concept design including external and internal configuration, mass properties, engine performance, trajectory analysis, aeroheating results, and concept cost assessment are given. Highlights of the distributed, collaborative design approach and a summary of trade study results are also provided. NOMENCLATURE C t thrust coefficient I sp specific impulse (sec.) I* equivalent trajectory averaged I sp (sec.) MR mass ratio (gross weight/burnout weight) q dynamic pressure (psf) T/W e

Initial results are reported from an ongoing investigation into optimization techniques applicable to multidisciplinary reusable launch vehicle (RLV) design. The test problem chosen for investigation is neither particularly large in scale nor complex in implementation. However, it does have a number of characteristics relevant to more general problems from this class including 1) the use of legacy analysis codes as contributing analyses and 2) non-hierarchical variable coupling between disciplines. Propulsion, trajectory optimization, and mass properties analyses are included in the RLV problem formulation. A commercial design framework is used to assist data exchange and legacy code integration.

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This paper presents a new conceptual launch vehicle design in the Bantam-X payload class. The new design is called Stargazer. Stargazer is a two-stage-toorbit (TSTO) vehicle with a reusable flyback booster and an expendable LOX/RP upper stage. Its payload is 300 lbs. to low earth orbit. The Hankey wedge-shaped booster is powered by four LOX/LH2 ejector scramjet rocket-based combined-cycle engines. Advanced technologies are also used in the booster structures, thermal protection system, and other subsystems. Details of the concept design are given including external and internal configuration, mass properties, engine performance, trajectory analysis, aeroheating results, and a concept cost assessment. The final design was determined to have a gross mass of 115,450 lb. with a booster length of 99 ft. Recurring price per flight was estimated to be $3.49M. The overall conceptual design process and the individual tools and processes used for each discipline are outlined. A summary of trade study results is also given. NOMENCLATURE C t thrust coefficient I sp specific impulse (sec.) q dynamic pressure (psf) T/W e engine thrust-to-weight ratio This paper summarizes part of an 18 month Bantam-X concept study conducted by the Space Systems Design Laboratory at Georgia Tech with the support and collaboration of NASA Marshall Space Flight Center. The study goal was to investigate a promising concept based on rocket-based combinedcycle (RBCC) propulsion for longer range Bantam-class missions. NASA MSFC currently has an ongoing development program in RBCC engines.

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