Trade-off study on structural configuration of cryogenic composite tank for reusable launch vehicles

In order to develop efficient space transportation systems, composite materials application to cryogenic propellant tanks would be one of the most important technological challenges particularly when aiming to establish Single Stage to Orbit (SSTO) space transportation vehicles which have been dreamed of for long years. However, as recognized through the development efforts and failures such as the X-33 experimental vehicle by the United States, many technological barriers still remain mainly due to the cryogenic brittleness of resin systems and severe thermal environments on the way to establish high reliability space structures. In this study, previous and current research results in this field are reviewed particularly focused on material and structural characteristics at cryogenic temperature. Then several kinds of possible structural options are proposed. Options discussed include stringer-frame stiffened CFRP panel with internal or external foam insulation and three kinds of sandwich structures. Preferable structural configurations are searched based on structural design trade-offs. Finally necessary technological tasks to be conducted in the future are identified.