Design of a One-Third Scale Multi-Tethered Aerostat System for Precise Positioning of a Radio Telescope Receiver

The National Research Council of Canada’s Herzberg Institute has proposed a design for a new radio telescope known as the ‘Large Adaptive Reflector’ (LAR). The LAR telescope is comprised of a 200 m reflector and a receiver held aloft at an altitude of 500 m by a tethered aerostat. The position of the receiver is actively controlled by a series of tethers connected to winching systems on the ground. Computer simulations of the LAR positioning system have shown that the proposed design holds a great deal of promise. To add confidence to these results and give further assurance that the concept is practical, experimental validation is crucial. Therefore design and construction was undertaken of a one-third-scale model of the multi-tethered aerostat component of the LAR to further study the dynamics and control of this subsystem. The design process begins with an analytical study of the scaling process. All variables liable to affect the dynamics of the system were identified and dimensionless groups were formed by applying Buckingham’s Pi Theorem. Once the desired physical characteristics of the scaled system had been identified, components were chosen to satisfy those characteristics. The key components to be selected included the aerostat, tethers, sensing instruments and winches. The design process for selecting these components is discussed and an overview of the construction of the system is given.