One point of main purpose of these experiments is to reveal certain temperature dependent behavior of thermal expansion coefficients of theconstituents of CFRP. The second purpose is a comparison between experimental and numerical results of an influence of αm on αx and αz. The third is to estimate unknown αffr and αfz of carbon fiber itself by such a comparison. Testing apparatus used here is an interferometric dilatometer utilizing gas laser which is sensitive enough to measure temperature dependent α's. Involved behavior of α's of unidirectional CFRP and Epoxy resin is elucidated by virture ofthese experiments and the authors' preceding analysis concerning this subject. For example, temperature dependency of αm has a predominant effect on αx, as it was suggested by the analysis. The estimated αfr and αfz are quite different from the corresponding values of pyrographite.
The Orbit determination accuracy required to maintain a geostationary satellite within ±0.1° longitude and latitude band is discussed. And through an experiment of the orbit determination of INTELSAT-IV and ATS-I, it is confirmed that this accuracy can be accomplished by the present tracking equipment and orbit determination software. Moreover, some useful suggestions are givento develope a more simplified station keeping software system for a geostationary satellite.
In recent years accuracy requirement for satellite attitude control system is getting increasingly stringent and wobble of a spinning satellite has received attention. In this paper attitude dynamics of an axisymmetric spinning satellite is analyzed and the beat of nutation and wobble is found to exist. A wobble reducer composed of two movable masses is proposed. Canadian communication satellites adopted a wobble reducer composed of three masses. The reduction of mass number from three to two contributes to the reduction of weight and the simplification of mass control logic. The possibility of wobble elimination using this wobble reducer is shown theoretically. Computer simulation is conducted and the transient attitude stability is confirmed when the wobble reducer together with a dash-pot-type nutation damper is used even if the mass of the nutation damper moves in a way unfavourable to dynamic balance. An experiment using a spherical-air-bearingsupported satellite model and mini-computer was carried out. The result of the experiment confirmed the attitude dynamics analysis including wobble and nutation. The performance of the wobble reducer was also confirmed through the experiment.
A flow visualization study for the co-axial rotor in hover was conducted. By comparing the tip vortices behaviours of the co-axial rotor arrangement with those of the single rotor one, the influences of the wake geometry on the optimization of the hover performance were clarified, under the condition that the both have produced the same rotor thrust. It was found that the co-axial rotor could offer the more improved flow field around each rotor by relocating the tip vortices and could also have a potential for alleviating the mutual interference between the rotor-wake effectively. The results of the flow visualization study were well consistent with those of the force testing and its validity was ascertained.