Birds are highly capable and maneuverable fliers, with the ability to fly at both high and low speeds in a variety of flight conditions. They engage in a multitude of complex flight maneuvers, such as takeoff, landing, gliding, perching, diving, and more, by changing the shape of their wings during flight in a variety of complex ways. These abilities are not shared with today’s small unmanned aerial vehicles (UAVs).
Unlike birds, current small UAVs struggle to fly in gusty and turbulent conditions and are mostly relegated to fair weather flight. UAVs lack the agility of birds in environments that are relatively close to ground level, filled with obstacles such as trees and buildings. Increasing the agility and maneuverability of fixed wing drones, or stability in gusty conditions of quadcopters and similar devices remains challenging. Development of an adaptable wing with morphing wingtips could help alleviate the issues faced by modern UAVs. Facing these challenges requires a multi-disciplinary thought approach, combining ideas from mechanical engineering, electrical engineering, aerospace engineering, and material science.
Our goal is to design a passively tuned wingtip device that responds to aerodynamic conditions. The device will have multiple wingtips, inspired from bird feathers, in an attempt to increase the maximum lift with a minimal drag penalty. A static model with non-deployable wingtips has been tested in a wind tunnel to determine the aerodynamic effect of various wingtip geometries, accounting for factors such as: wind speed, wingtip gap separation, base wing angle of attack, and wingtip angle of attack.
Results have shown that, for certain wingtip configurations, the maximum coefficient of lift has increased by anywhere from 3.7 – 6.9%. The coefficient of drag increased by 1.7 – 12.9% under the same conditions. These results show that these devices can be useful in situations requiring maximum lift, such as when carrying a large payload. Other promising applications include perching maneuvers where maximum lift as well as large amounts of drag are required.
The next stage in the project is to analyze nonplanar wingtip devices to see if further reductions in total drag can be achieved while maintaining the maximum coefficient of lift. After that, an aeroelastic model will be developed so that a passively tuned deployable wingtip device can be designed, simulated, and tested in a wind tunnel.