Weight Analysis of Two-Stage-To-Orbit Reusable Launch Vehicles

Abstract

In response to military requirements for responsive and low-cost space access, this study provides an objective empty weight analysis of potential reusable launch vehicle (RLV) configurations. Many studies have been performed with hydrogen-fueled RLVs, but there has been limited research into RLVs using hydrocarbon scramjet engines, which have the potential to be more practical and operable for responsive military operations. To fill this void, this study used hydrocarbon dual-mode scramjet (DMSJ) engine performance data from the U.S. Air Force HyTech program in the propulsion systems of the rocket-basedcombined-cycle (RBCC) and turbine-based-combined-cycle (TBCC) booster vehicles. Each two-stage-to-orbit (TSTO) RLV has a fixed payload requirement of 20,000 lbf to low Earth orbit. The booster propulsion systems considered in the baseline study include rocket, turbine, RBCC, and TBCC. Empty weight sensitivity analyses considered the effects of the orbiter fuel selection and the effects of the turbine installed thrust to weight ratios for the RLVs using afterburning turbine engines. Based on the assumptions in this study, the vertical-takeoff-horizontal-landing (VTHL) RLVs are lighter than the horizontal-takeoffhorizontal-landing (HTHL) RLVs. Additionally, the change in orbiter propellant has either negligible or no empty weight savings for the VTHL RLVs, while it leads to substantial empty weight savings for the HTHL RLVs. For the HTHL RLVs, increasing the turbine installed thrust to weight ratio causes a significant decrease in RLV empty weight.