This paper presents a simple device for augmenting attitude stability of a VTOL airplane supported by one-ducted-fan, at hovering. It is based on an aerodynamic drag generated at a place higher than vehicle center-of-gravity (CG). Since the problem becomes nonlinear, the time-marching technique is used. The effect is remarkable, even with a reasonable size of a sail and at a reasonable height over the CG. It is suggested to use a gas-bag or wind-mill in place of a sail.
For the ETS-VI antenna system appling to multibeam satellite communication experiments, a new on-board antenna pointing control system and its components were developed to achieve an antenna pointing accuracy requirement. The antenna pointing control system consists of both a conventional satellite attitude control system and an antenna drive control system. The antenna drive control system tracks a beacon transmitted from an earthstation independently of satellite attitude control by driving a sub-reflector. Control accuracies of the system were confirmed to be within 0.002 degrees through control simulations using on-board hardwares with two three-axis motion tables and the RF sensor simulator. Through antenna pointing error analysis based on each errorr source data, the ETS-VI antenna pointing accuracy is estimated to be within 0.015 degrees.