Ascent phase thermal analysis of Long Duration Balloons.

Long Duration Balloons are suitable platforms for scientific research to study the Earth and the Solar System. From the thermal point of view, these platforms are analysed at the floating altitude using data of the thermal environmental conditions considering the local characteristics and the seasonal variability. Nevertheless, depending on the launch site conditions and the launch day time, the minimum temperatures could appear during the ascent phase. This is because the balloon-payload system is exposed to free air and the convective heat transfer could drive the thermal behaviour of the onboard equipment. This analysis requires a dynamic study of the balloon trajectory for determining the relative speed with respect to the air as well as an appropriate thermal modelling considering the radiative and convective heat transfer. The aim of this paper is to explain the main characteristics of the ascent phase from a thermal point of view and to show how an ascent phase analysis for a Long Duration Balloon system can be performed using ESATAN-TMS. In order to give examples for the explanation the full process has been particularized to the SUNRISE III mission. • Thermal modelling of a generic payload onboard a Long Duration Balloon for ascent phase analysis. • Determination of the balloon film influence on the payload thermal behaviour. • Determination of the worst-case relative wind speed on the balloon-borne system for forced convection estimations. • Thermal analysis of SUNRISE III mission during the ascent phase using ESATAN-TMS. [ABSTRACT FROM AUTHOR]