Dynamic analysis of an ascending high altitude tethered balloon

A study of the feasibility of positioning a platform at an altitude of 20 kilometers in a fixed wind field is presented. The system considered consists of a 14,125 cubic meter natural shape zero pressure balloon tethered with a 4.82 mm diameter Kevlar cable. The average wind field over Hill Air Force Base (AFB) in November has been assumed for the study. Both a static and a dynamic analysis of the system are presented. The static analysis determines the design requirements based on a balloon positioned at an altitude of 20 kilometers. On the other hand, the dynamic analysis takes into consideration the velocity of the balloon, as well as the tether, at each instant in tune as the system ascends. It was discovered that the static solution does not provide the required information concerning maximum tether force, tether length or ground track. The dynamic results indicate the necessary speed and capacity of a winch to reach the design altitude while maintaining the tether forces within an acceptable margin of safety. A tethered platform is feasible as long as the dynamic properties of ascent are taken into consideration.