Experimental characterization and simulation of a tethered aerostat with controllable tail fins

This research investigated the use of a streamlined aerostat with movable tail fins to control the pitching motion of an aerostat in a turbulent wind environment. The goal of the research was to reduce the pitch fluctuations of the aerostat by actively controlling the tail fins. A streamlined aerostat with four rigid tail fins was modified to include flap type trailing edge control surfaces on the horizontal tail fins. Airborne sensors and a ground station with wind sensors were used for the control of the aerostat and data logging.;An additional goal of this research was to adapt a non-linear dynamic simulation to simulate the controllable aerostat used in this experiment. The experimental aerostat's aerodynamic and geometric properties were characterized for use in the dynamic model. In general, the 'non-dynamic' quantities in the simulation showed a good match and the dynamic variables did not show as good of a match between the simulation and the experiment suggesting that the model does not correctly represent the dynamic behaviour of the aerostat.;In order to characterize its motion and to establish a performance baseline, the aerostat was flown numerous times without active control. The effectiveness of the tail-fin control surfaces was determined by measuring the open-loop response of the aerostat to a step change in the control surface deflection. The results from the uncontrolled and open loop testing were used to develop the closed loop control system which was then tested experimentally.