Analysis and Design of Robust Helium Aerostats

Tethered helium aerostats are receiving renewed attention in the scientific and surveillance communities. However, conventional aerostats cannot consistently survive high winds. The goal of this research was to design an aerostat that could be deployed for very long periods, thus reducing operating costs and interruptions in data acquisition. Existing designs and fabrication techniques were first reviewed and replicated in the construction of a 2.5-m-diam spherical aerostat. The constructed balloon was then flown outdoors to observe its operational qualities. The results from the flights were used to inform finite element models evaluating the critical stresses in the envelopes of 10.15-m-diam balloons with two different tether attachment schemes. The models suggested that conventional aerostats would fail in high winds, due to stress concentrations where the tethers meet the envelope. A third model was created to appraise the performance of an ultrarobust aerostat with a partial-hard carbon fiber shell in critical areas, which was able to achieve an operational safety factor of 1.6 in a 46.3-m/s (90-kt) wind.