Aerostructural Performance of Distributed Compliance Morphing Wings: Wind Tunnel and Flight Testing

The aerodynamic and structural performance of a morphing wing concept, based on fully compliant structures and actuated by closed-loop controlled solid state piezoelectric actuators, is investigated numerically and experimentally. The morphing wings are designed for a 1.75-m-span unmanned aerial vehicle operating at up to 30 m/s, following lightweight aeronautical construction principles. The goal of providing roll controllability exclusively through morphing is achieved with a concurrent aerostructural optimization, considering static and dynamic aeroelastic effects. The aeroelastic response of the wings is experimentally assessed through wind tunnel tests, performed at different speeds, angles of attack, and actuation levels. The test campaign confirms the ability to achieve lift and rolling moment variations while maintaining a high aerodynamic efficiency, and the results closely match the numerical predictions. An 8-min flight test is performed by replacing the unmanned aerial vehicle wings with the morphing system, demonstrating the capabilities of the concept in its operational environment. This experimental assessment confirms the performance of the design, its robustness, and the possibility of implementing the morphing concept and the required high-voltage control system in small unmanned aerial vehicles. Ultimately, the results show the possibility of replacing the conventional ailerons of similarly sized airplanes with the proposed solution, achieving significant efficiency improvements while guaranteeing controllability.