POSITIONING THE BATTERY SYSTEM IN AN ULTRA-LIGHT SOLAR POWERED HALE UAV

Kurzfassung

The German Aerospace Center (DLR) is currently developing an unmanned ultra-light solar powered High-Altitude Long Endurance (HALE) aircraft in the project High Altitude Platform (HAP). To overcome the nightly period of missing solar power, a battery system is required. Being the heaviest subsystem in the aircraft, the positioning of the battery system involves many design disciplines. The overall aircraft concept requires a specific location of the center of gravity, which is highly influenced by the battery system. Locating the battery in the aircraft’s main wing is necessary to reduce bending moments in the wing spar. Torsion moment in the spar, thermal management, and wiring are depending on the position in the cross-section of the wing. As an additional difficulty, the positioning of the battery is influencing many following decisions and has to be made early in the design process. In this project stage, the available analyses have limited accuracy, so the positioning is driven by robustness of the decision. This paper shows, which design disciplines are affected by this decision and explains the chosen placement in the front of the spar, which is mainly driven by design robustness of thermal aspects.