High altitude airship station keeping and launch model development using output from numerical weather prediction models

The High Altitude Airship (HAA) is suited for a wide variety of demands from the military as well as from the commercial sector. In particular, solar powered, unmanned, high-altitude airships that remain geostationary year-round over hostile territories are of great interest to the military. This “eye in the sky” can provide information on enemy troops at better resolutions and much lower costs than conventional geostationary satellites. The power required by an HAA increases as the wind speed cubed which in turn increases the size, weight, and cost of the airship. Because of this cubic relation to the wind, the airship design is very sensitive to the choice of the design speed. This choice depends on the operational location and the percent of time the airship must remain on station. Accurate spatially and temporally resolved wind speeds are needed to analyze/design a HAA. This thesis uses output from state-of-the-art Numerical Weather Prediction (NWP) models to accurately resolve the wind speeds in order to accomplish two objectives. The first objective is to develop two station keeping models that evaluate the amount of time an airship is available for its geostationary mission. The second objective is to develop a launch model that evaluates the drifting distances from a launch site. The first station keeping model developed is a point model in which the airship’s year-round station keeping capability is estimated by examining 28 years of low resolution NWP wind data at a single point. From the point model analysis, an estimate is found of the extra power needed to keep the airship on station for longer periods of time. Next, a flight path model is developed which estimates the airship’s station keeping capability during a storm using high resolution NWP model wind data along an airship’s flight path. This flight path model takes into account the travel time needed for the airship to avoid the high winds as they approach the airship. From the flight path model analysis, a flight path which acts to minimize the time off station is determined. Finally, a mathematical model of a launch is developed and a simulation is created for a summer and winter launch at four different times of day using medium resolution NWP model wind data. The expected airship trajectory and the maximum drifting distance from the launch site is found for each of the eight simulations using two different launch strategies