Spin Free Analytic Platform Type Guidance and Control System

The overall guidance and control system with the Spin Free Analytic Platform (SFAP) type attitude reference that is used for the M-3S rockets that launched Japanese Scientific Satellites, is shown with detailed description for the function of each composing unit, and results of evaluation from actual flight experiments are also shown. The SFAP attitude reference system is provided with two RIGs for pitch and yaw mounted on a roll stabilized platform, on which also mounted a roll RIG compensating the coning effect arising on the platform using the signal fed back to a Roll RIG torquer from the output of Digital Differential Analyzer (DDA) which calculates pitch and yaw angles in strapdown mode. This also makes it easy to correct reference attitude angles by radio commands from a ground tracking station. Specified performance of drift rate of the overall system is within 0.5°/min. From experimental results, it was assured that this value was realized for more than 5 flights. Some results of actual flight experiments are also shown.