Ascent performance of an air-breathing horizontal-takeoff launch vehicle

Advanced manned launch systems studies underway at the NASA Langley Research Center are part of a broad effort examination of options for the next manned space transportation system to be developed by the United States. One promising concept that uses advanced technologies is a fully reusable, single-stage horizontal-takeoff vehicle that uses airbreathing propulsion. This paper discusses some potential ascent issues that could influence the design of this class of launch vehicles. Two issues are identified. The first issue is that the drag losses due to aerodynamic trim can require a significant fraction of the total energy required to achieve orbit. The second issue is the difficulty in achieving precision insertions with a vehicle that coasts unpowered from a high dynamic pressure to orbit.