493. Weight Optimization of a Two Stage Reusable Orbital Carrier

Paper

Abstract

Man’s desire to expand his knowledge of the solar system and the universe wiL. lead to a steadily increasing number of trips between the earth’s surface and various orbits above our atmosphere. Technically, these trips are already fe:asible with either expendable or reusable boosters. However, at the increased launch rates expected within the next 10 to 20 years, the cost of expendable boosters becomes prohibitive. To remain within the cost constraint of that portion of the national budget allocated to space exploration, without s:?riously restricting future space travel, requires the development of efficient reusable launch systems.
During the conceptual d::osign phase of these reusable syst2ms, weight and performance studies ar3 required to eliminate unpromising configurations and to assist in selecting and optimizing the most feasible designs. The objective of this paper is to present a means for performing these weight studies.
A method is for rapidly determining the take-off weight and system dry weights of a two-stage reusable booster. The stage weights are described in quation form by deriving simplified expressions for the major functional components based on background experience and related technology. As baseline configurations are developed, these expressions are revised and expanded. As more detailed information is required, calculations may be greatly accelerated through the use of digital computers. Typfral equations for each stage are shown, including both all-rocket and rocket-airbreathing propulsion combinations for the first stage. Effects on stage and system weights caused by variations in sign parameters such as staging velocity and propulsion systems are presented.
The two-stage booster which is used as an example has a LO2/RP-l fueled, winged first stage and a LO2/LH2 fueled, winged body second stage which also contains the payload. Tne ombined stages take off horizontally and, after completing its mission, each stage also lands horizontally.