Meeting Abstract
Butterfly scales covering the wings represent a multifunctional surface. Besides providing color to the wings and serving as a superhydrophobic surface, they may also play an aerodynamic function. The scales (approximately 0.1 mm in size) form a roof shingle pattern over the wings, and due to the fact that the scales protrude upwards from the wing a three-dimensional micro-pattern is present. We will discuss a hypothesis as to how the scales may function to alter the drag of airflow passing over the surface and will present results from flight tests of live Monarch (Danaues plexippus) specimens. Using the Autonomous Tracking and Optical Measurement (ATOM) Laboratory located at the University of Alabama Huntsville, 22 Vicon T40 cameras permitted millimeter level tracking at 100 fps of reflective markers placed on specimens freely flying in a 4 m x 6 m x 7 m volume. Insects first flew with their scales intact and then again after careful scale removal. The flight path, flapping frequency and wing flapping angle were recorded. Differences in these variables observed over more than 20 specimens will be discussed. Initial results indicate that without their scales some specimens appeared to compensate with higher flapping frequency for similar energetic flight, while others had reduced flight speeds for similar flapping frequencies. Both of these observations indicate a potential aerodynamic benefit due the presence of the scales, and this may be linked to the leading-edge vortex formation and induced drag.
