Bio-Inspired Design: Avian Inspired Morphing Wing

Abstract

Small-scale fixed-wing UAVs, Unmanned Aerial Vehicles, are useful in a wide range of applications, ranging from photography, surveillance, delivery, or environmental protection. Currently, most have to be caught by hand, require a long runway for roll-out, must land in a net, or have to carry parachutes. In order to improve the precision UAV landing capabilities, we look to birds for bio-inspiration as they have the capabilities to land quickly and in confined spaces while maintaining control over their descent rate and location. This process is also known as perching, and replicating this would allow UAVs to perform planted landings by bringing their horizontal and vertical velocities to near zero prior to touchdown, which would greatly increase their landing precision and expand the mission capability of small-scale UAVs.

A study on this topic was undertaken by Anna Alvarez and Dr. Aimy Wissa. They researched the influence of two different wing configurations inspired by the morphology and agility of the Harris Hawk in improving the aerodynamic efficiency at high angles of attack for UAVs during a pitch-up maneuver, a crucial stage in perching. The results of their wind tunnel experiments showed that the M-shaped wing configurations, which mimic the Harris Hawk’s swept wings during its perching maneuver, improved aerodynamic efficiency at high angles of attack by more than 80 percent. They also found that the M-shaped configurations aided in creating a pitch-up moment, and when deployed asymmetrically, they can be used for roll and yaw control. My project sought to expand on this existing research by implementing this research by designing, fabricating, and testing a physical flight-worthy actuated wing that integrates a four-bar mechanism, as discussed in prior studies, and a servo motor in the actuation of the wing into the desired M-shaped configuration mid-flight. It also sought to validate the presence of a pitching moment as a result of the M-shaped configuration through wind tunnel testing. Moreover, during the course of this thesis, a fully functional morphing wing was built that could achieve the M-shaped configuration using a four-bar mechanism. The wing underwent successful dynamic wind tunnel testing and produced results that are consistent with static wind tunnel testing done with the M-shaped configurations. Moreover, it was found that the a pitching moment is indeed induced by the use of a morphing wing that mimics the M-shaped configuration of bird wings.