Shape and envelope tension prediction of natural shaped high altitude balloons

Abstract

The envelope tension is governed by curvature of external surfaces and shape of the balloon which is affected by the thermal characteristic of the envelope and lifting gas. But the researches about the balloon shape and envelope tension with thermal effect are rare. Combined with the balloon geometrical shape model and thermal model, the minimizing total potential energy model is solved by numerical method to predict the balloon geometrical shape and envelope tension. The effects of the flight altitude, lifting gas mass, and flight time on the balloon shape and the tension distribution were numerically investigated in detail. The results showed that the extreme values of the meridional envelope tension appear at the top and bottom of the balloon, while the meridional tension was much greater than the circumferential tension. Furthermore, the diurnal variation of the lifting gas temperature will lead to the change of flight altitude and volume, which causes a change in the shape and envelope tension. The results demonstrated that the theoretical approach suggested a pathway towards improving the structural design for a high altitude balloon.