Fluid-Structure-Sound Interactions and Control

Abstract

High Altitude, Long Endurance (HALE) aircraft can achieve sustained uninterrupted flight time if they use solar power. Wing morphing of solar powered HALE aircraft can significantly increase solar energy absorbency. An example of the kind of morphing considered in this paper requires the wings to fold so as to orient a solar panel to be hit more directly by the sun’s rays at specific times of the day. In this paper solar powered HALE flying wing aircraft are modeled with three beams with lockable hinge connections. Such aircraft are shown to be capable of morphing passively, following the sun by means of aerodynamic forces and engine thrusts. The analysis underlying Nonlinear Aeroelastic Trim And Stability of HALE Aircraft (NATASHA), a computer program that benefits from geometrically exact, fully intrinsic beam equations, and a finite-state-induced flow model was extended to include the ability to simulate morphing of the aircraft into a ‘‘Z’’ configuration. Because of the ‘‘long endurance’’ feature of HALE aircraft, such morphing needs to be done without relying on actuators and as near zero energy cost as possible. The emphasis of this study is to substantially demonstrate the processes required to passively morph a flying into a Z- shaped configuration and back again.