Optimization of future earth-to-Leo launch vehicle concepts

A comparison of the performance, based on direct and indirect operating costs, of three laaunch vehicle concepts designed for transportation of personnel to and from low-earth orbit, is presented. The three concepts are: (1) ABHTOL, a fully reusable air-breathing horizontal takeoff and landing vehicle; (2) VTHOL, a fully reusable rocket powered vertical takeoff and landing vehicle; and (3) XVTOHL, a rocket powered vertical takeoff vehicle with expendable and reusable stages. The direct operating cost, which includes research and development, production, and support, is studied and graphs are provided. The cost of maintaining launch facilities, mission control, and administrative support for the vehicles is examined. It is concluded that there is no major difference in operating costs for the three launch vehicles and a future direct operation cost of $500/pound in orbit is estimated.