Design optimization of a tri-lobed solar powered stratospheric airship

The increased interest over multi-lobed hybrid airships which have been recently identified as an ideal platform for high altitude long endurance applications urges to develop a methodology for conceptual design optimization. The sizing methodology estimates the area of solar array required to meet the constraints of energy balance and the weight/lift equilibrium. The methodology involves the coupling of four disciplines (viz., Environment, Geometry, Aerodynamics, and Energy) and accounts for their mutual interactions. Sizing of the airship is carried out in terms of five design variables corresponding to the geometry and layout of the envelope and the solar array. This methodology is coupled to an intelligence-based heuristic algorithm viz., Particle Swarm Optimization (PSO) to obtain the configuration corresponding to a minimum area of solar array for such an airship, meeting the user-specified operating requirements. The effect of wind speed, airship attitude and altitude, geographical location and day of operation on the optimum area are included in this study. The results show the effect of season and operating conditions of deployment on the optimal envelope shapes obtained for deployment on specific days of the year. This study helps in the preliminary design of solar array on an unconventional stratospheric airship.