Investigation of Aerodynamics of Morphing Wing-Tips

Morphing aerodynamic surfaces are receiving growing attention in modern aircraft development due to the demand for improved efficiency and enhanced performance. Bio-inspired morphing concepts, in particular, have gained interest as birds operating at low Reynolds numbers exhibit exceptional agility, capabilities that conventional fixed-wing UAVs generally lack. This study investigates a blended cant-angle morphing wingtip, designed for a fixed-wing UAV, to quantitatively assess its ability to manipulate aerodynamic forces. The work also examines the feasibility of employing symmetric morphing wingtips as active control surfaces to achieve controlled roll maneuvers.

The wingtip was developed for a medium-sized UAV, with aerodynamic simulations carried out at a cruise Reynolds number of 250,000. Aerodynamic force characteristics were evaluated using computational methods and validated through wind tunnel experiments. A numerical study was performed on a series of wing models featuring different cant angles to determine drag variations under multiple angles of attack. Complementary wind tunnel tests were conducted on a scaled wing-and-wingtip assembly, and additional computational analysis using Ansys Fluent was performed to assess the capability of the morphing tip as a control surface.

Results demonstrate that the morphing wingtip generates notable changes in aerodynamic forces, with cant angles around 30° providing the most favourable lift response across a range of angles of attack. Lift-to-drag ratio analysis indicates that a 0° cant angle is optimal for cruise. Control-surface evaluation further shows that differential cant-angle adjustments between the two wingtips can produce controlled rolling, with required roll rates achievable through precise actuation. A working prototype of the morphing wingtip was fabricated, incorporating a motor-driven actuation system to realise the desired geometric transformations.