Rate Control System for Sounding Rockets

Abstract

DLR/Moraba has a long history in the development of Rate Control Systems (RCS) which have been flown for several programs for research in weightlessness in Europe and Brazil. They had been used in various European μG programs such as MAXUS, MASER and TEXUS. Moraba has now developed a RCS for 14 inch payloads. This RCS uses a standard interface and can be easily joined to a REXUS service module. This combination (RCS and REXUS service system) came into operation for the MAPHEUS maiden flight. MAPHEUS (Materialphysikalisches Experiment unter Schwerelosigkeit) is an internal project of the DLR. The payload for this project, including the service systems and 4 experiments, flew on a Nike/improved Orion two stage motor which took the payload to an altitude of about 140.8 km, providing a period of weightlessness of more than 187 seconds. To achieve conditions of weightlessness above the atmosphere a RCS system is indispensable. The aim of the RCS is to reduce the angular rates of the payload significantly above the atmosphere in order to minimize the centrifugal accelerations to a level lower than 10 μg. This article describes the principle of a rate control system. It provides an insight into the interaction between the control loop, payload and actuators.