Extending the Life and Recycle Capability of Earth Storable Propellant Systems

Rocket propulsion systems for reusable vehicles will be required to operate reliably for a large number of missions with a minimum of maintenance and a fast turnaround. For the space shuttle reaction control system to meet these requirements, current and prior related system failures were examined for their impact on reuse and, where warranted, component design and/or system configuration changes were defined for improving system service life. It was found necessary to change the pressurization component arrangement used on many single-use applications in order to eliminate a prevalent check valve failure mode and to incorporate redundant expulsion capability in propellant tank designs to achieve the necessary system reliability. Conceptual designs were developed to show how each of these provisions might be implemented. Material flaws in pressurant and propellant tanks were noted to have a significant effect on tank cycle life; proof testing was defined as the best method of assuring that the tanks were capable of providing the desired cycle life. The appropriate selection of proof-to-working pressure levels is fundamental to the successful application of the tests to cycle life determination. Finally, maintenance considerations dictated a modularized systems approach, allowing the system to be removed from the vehicle for service and repair at a remote site. A unique component packaging concept was studied as a means of facilitating repair and reducing maintenance downtime.