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

Abstract

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.

Effectiveness of Twist Morphing Wing on Aerodynamic Performance and Control of an Aircraft

“…Novel design concepts with multiple morphing elements were utilised and the results show the concept is superior to more traditional methods under selected test conditions such as ϕ=-6° with both sufficient compliance in twist, adequate resistance to aerodynamic bending, and minimal surface distortion all demonstrated successfully in flight. In addition to all, 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 by Molinari et al [27]. The concept was tested in the wind tunnel and also deployed to model aircraft to demonstrate the roll capability of an aircraft.…”

Control of flow separation around an airfoil at low Reynolds numbers using periodic surface morphing

“…Bilgen and Friswell[35] developed a novel design for a variablecamber airfoil employing a continuous inextensible surface with bonded MFC actuators which can achieve significant change in aerodynamic response. Molinari et al[36] investigated numerically and experimentally the aerodynamic and structural performance of a wing morphed by MFCs. The wing was tested in a small unmanned aircraft flight and proved that roll controllability can be achieved exclusively through morphing.…”

Recent researches on morphing aircraft technologies in Japan and other countries

“…Dayyani et al provided a comprehensive review of the literature on such corrugated structures, presenting broad ranges of applications (Dayyani et al, 2015). Molinari et al studied the aerodynamic and structural performance of a morphing wing concept through their simulations and experiments (Molinari et al, 2016). Their wing model consisted of fully compliant structures and solid-state piezoelectric actuators.…”

“…Due to their fast response and wide band-width, they are also considered as an alternative actuator for wing morphing. Molinari et al proposed a morphing wing concept integrating the compliant structures and piezoelectric MFC actuators (Molinari et al, 2016). Bimorph piezoelectric actuators were installed on the upper skins to allow camber morphing of the wing with compliant structures.…”