Mini-UAV structure optimization for efficient thermal soaring

This paper investigates the impact of structural flexibility on the thermal soaring performance of a mini-UAV wing. Three optimization problems are formulated to identify the optimal set of structural parameters that maximize energy extraction in both steady and unsteady soaring scenarios. The ASWING aeroelastic simulation tool is first validated experimentally and then employed to solve these optimization problems. Results suggest that increased structural flexibility yields significant benefits only in unsteady soaring (dolphin-kick strategy), but not in steady thermal soaring. For the latter, the apparent performance gains from structural optimization stem more from an effective change in the rigid geometry than from actual aeroelastic advantages. Furthermore, it is shown that active pitch control can yield equal or superior benefits compared to passive structural adaptations. These findings highlight the limitations of flexible wing designs for general-purpose soaring UAVs and suggest that robust aerodynamic geometry coupled with smart control may be a more practical design direction.