European Cooperation on Flow Separation Control

Abstract

Most of today's launch vehicles use parallel staging with two or more strong solid rocket boosters and a core stage engine; the latter is ignited at ground and operates up to high altitudes, where the ambient pressure is close to vacuum. During take-off and the first phase of flight, the strong boosters make up most of the thrust, whereas the contribution of the core stage is comparably small. After booster separation, which usually takes place in altitudes where the ambient pressure is very low, the core stage alone accelerates the launcher. Therefore, the vacuum performance of the core stage engine has a considerable influence on the payload, whereas its sea-level impulse is of minor importance. An obvious way to enhance the payload of such launchers is hence to increase the area ratio e of the core engine nozzle.