Design and Field Trials of a Payload Recovery Device for Tethered Aerostats

Abstract

This paper describes the design fabrication and testing of Payload{a} Recovery Device (PRD) that gets activated automatically if tether of an aerostat breaks. The recovery of payload is accomplished in three stages, viz., tether breakage detection, signal transmission, and device activation. The envelope of aerostat is deflated by deploying a mechanism that results in a small circular hole on its top. As the LTA gas in the envelope escapes, the buoyancy of the aerostat decreases and it gradually descends. The size of the hole controls the gas leak rate and hence the velocity of descent. A model for simulating the breakaway characteristics of a spherical aerostat was also developed, which estimates the amount of drift and touchdown velocity as a factor of various parameters such as the hole diameter and deployment altitude, for a single and double chamber envelope. The prototype system was then field tested in an indoor and outdoor aerostat.