PROPULSION SYSTEM CONCEPTS FOR SINGLE-STAGE SHUTTLES

Abstract

This chapter discusses the propulsion system concepts for single-stage shuttles. There are two basic approaches to the single-stage-to-orbit (SSTO) space transportation system, namely, a winged vertical takeoff and horizontal landing (VTOHL) vehicle and a vertical takeoff and vertical landing (VTOVL) vehicle. The VTOHL vehicle is of conservative design and utilizes well-established concepts. It has one of the largest base areas of all winged vehicles. It consists of two main aluminum load-bearing LO 2 /LH 2 tanks mounted atop a wing-and-carry-through structure containing RJ-5 fuel. The chapter describes how the pressure influences design criteria and clarifies the importance of high chamber pressure for this mission. The propulsion concept involves combining in the same vehicle stage two propulsion modes operated sequentially to produce greater stage performance than is possible using either mode separately. An application of the principle of density optimization to engine design leads to the concept of a high-pressure staged combustion cycle LO 2 /RJ-5 rocket engine with a hydrogen-pumping system attachment, giving the engine the ability to also operate with LH 2 fuel. The simplest trajectory for mixed-mode application involves a sequential burn, that is, startup and shutdown of Mode 1 engines followed by operation of the engines in Mode 2.