Multi-objective Optimization for the Design of an Unconventional Sun-Powered High-Altitude-Long-Endurance Unmanned Vehicle

The use of High Altitude and Long Endurance (HALE) Unmanned Aerial Vehicles (UAVs) is becoming increasingly significant in both military and civil missions as High-Altitude Pseudo-Satellite (HAPS). Since this class of aircraft is usually powered by solar cells, it typically features unconventional configurations to maximize sun exposed surfaces. In the present paper, a Multidisciplinary Design Optimization (MDO) and a Multi-Objective Optimization (MOO) environment have been developed to provide a computational design tool for modeling and designing these unconventional aircraft in order to achieve as independent objectives the maximization of solar power flux, the maximization of the lift-to-drag ratio, and the minimization of mass. To this purpose, a FEM models generator, capable of managing unconventional geometries, and a solar power estimator, are suitably developed to be integrated within a multi objective optimization loop. The simultaneous use of MDO/MOO approaches, and Design Of Experiment (DOE) creation and updating principles, enables to efficiently take into account the multiple and contrasting objectives/constraints arising from the different disciplines involved in the design problem. The study is carried out by using two different commercial codes for multi-objective optimization and for structural and aeroelastic analyses respectively. The use of advanced MDO/MOO approaches revealed to be effective for designing unconventional vehicles.