Optimization of High Altitude Long Endurance (HALE) Vehicle Subject to Flutter Speed Constraint

Abstract

A class of air vehicles known as high altitude long endurance (HALE) has gained interest for a broad range of applications. Endurance requirements generally lead to vehicles with low mass and high aspect ratio wings. Such configurations are generally susceptible to aeroelastic effects including flutter. This work considers the aeroelastic behavior of a generic flying wing HALE vehicle configuration using generic stiffness and mass properties. An optimization study is presented that seeks to minimize penalties on trim drag and structural mass while satisfying a constraint on flutter speed. Optimization techniques employed include gradient based and a genetic algorithm. A Pareto Frontier is characterized that presents the set of designs that optimally satisfy the flutter constraint for a range of mass and drag penalties. This paper illustrates techniques that can be applied for optimization subject to aeroelastic constraints for general aircraft.