Preparation of Loads and Aeroelastic Analyses of a High Altitude, Long Endurance, Solar Electric Aircraft

Abstract

High altitude, long endurance aircraft can serve as platform for scientists to make observations of the earth over a long period of time. Staying airborne only by solar electric energy is, as of today, a challenge for the aircraft design and requires an extremely light weight structure at the edge of the physically possible. This paper focuses on the loads and aeroelastic aspects of such a configuration, discusses the selected strategies and presents the applied methods and tools, including the resulting models prepared for the HAPomega configuration currently under development at the DLR. Because of the structural flexibility and the slow speed of the aircraft, flight mechanical and flight control aspects interact with aeroelastics e.g. during a gust encounter, making a non-linear time domain simulation necessary. Both maneuver and gust loads are used for the structural sizing and result in a very light and slender airframe with very low eigenfrequencies.