Stability Control of Small Kite Balloon with Tensioned Anchoring Rope

A small captive balloon have been studied in order to get the information of local meteorology. We have tried to keep the designed altitude of a small captive balloon against the wind drag by controlling attack angle generating its lift force. Then the geometry of an ellipsoid has been focused for the balloon body rather than a spheroid that was used generally. The controlling attack angle is a passive way where elastic extendable cables are used to limit the inclination of balloon. The characteristics of cables were properly selected in order that the balloon could have the effective attack angle against the wide wind velocity. The controlling technique worked well unless the balloon was caught by unstable flow like a gust. In this study, we propose a method to keep the altitude of a captive balloon by the above technique in stable flow, and by changing tension of the anchoring rope periodically in unstable flow. Some artifices including a small change of the balloon geometry increased the stability of the attitude, and the successive tensioning was effective to restrain the rolling and falling. of the balloon in severely unsteady flow.