Gradient-Based Optimization of Solar-Regenerative High-Altitude Long-Endurance Aircraft

Abstract

In this paper we use gradient-based optimization to minimize the mass of a solar-regenerative high-altitude longendurance (SR-HALE) flying-wing aircraft while accounting for nonlinear aeroelastic effects. We design the aircraft to fly year round at 35°latitude at 18 km above sea level and subject the aircraft to energy capture, energy storage, material failure, local buckling, stall, longitudinal stability, and coupled flight and aeroelastic stability constraints. The optimized aircraft has an aspect ratio of 27.8, a surface area of 99.1 m 2 , and a mass of 508.8 kg. Our results suggest that thick airfoils provide greater structural efficiency than increased carbon fiber reinforced polymer (CFRP) ply thicknesses. We also perform several parameter sweeps to determine sensitivity to altitude, latitude, battery specific energy, solar efficiency, avionics and payload power requirements, and minimum design velocity.