Capsule Rescue Motors for SpaceLiner 7.1

Abstract

The hypersonic point-to-point passenger transport SpaceLiner 7 under development in DLR Bremen utilizes a capsule design for its emergency escape system and is activated in case of a catastrophic failure of its propulsion systems. In this study, separation motors for the capsule is designed and dimensioned with regards to a worst case scenario. This scenario is identified to occur at the launch pad where maximum fuel is present and the atmospheric pressure is highest resulting in the greatest amount of thrust losses, highest propagation speed and strength of the resulting explosive shockwave. During the design process, the maximum sustainable acceleration on the human body and any geometrical limitations are also considered. Furthermore an estimation of the structural mass of the motors is performed. The resulting separation system utilizes a five motor configuration that is designed for a nominal chamber pressure of 150 Bars and a burn time of two seconds. The motor consists of an end-burning grain geometry, an 80 % length bell nozzle consisting of a carbon-carbon material and a Kevlar based composite chamber. The resulting Structural Indexes are 11.8 % or 13.3 % for each motor depending on chosen overpressure limit. The overall conclusion is that the motors designed in this study fulfill all considered requirements but suggests more work can be performed. This includes considering dangers of fragmentation debris, more detailed structural mass analysis and further investigation of the propellant composition.