119.3 Saturday, Jan. 7 Experimental flight performance evaluation of forewing orientation in butterflies KOVAC, Mirko*; VOGT, Daniel; ITHIER, Danielle; SMITH, Michael, J.; WOOD, Rob, J.; Harvard University, Microrobotics Laboratory, http://micro.seas.harvard.edu email@example.com
The Harvard Microrobotics Laboratory is developing a series of biologically inspired flying micro robots at the scale of butterflies. One of the goals in this project is to optimize the wing shape and find optimal designs for gliding flight using a state of the art low speed wind tunnel which offers the unique ability to test butterfly size wings at scale. As a starting point we focus on wing shapes found in four butterfly species that are known for their distinct flight patterns and flight efficiency. For example, we selected migrating Monarchs (Danaus plexippus), which are famous for their astonishing capability of traveling large distances using a combination of hybrid flapping and gliding flight. Besides the ‘Monarch’ butterfly, we evaluate the wing shapes of the ‘Orange Aeroplane’ (Pantoporia consimilis), the ‘Glasswing’ (Acraea andromacha) and the ‘Fourbar Swallowtail’ (Protographium Ieosthenes). Based on museum specimens we extract the wing shapes and vary the forewing orientation angle systematically in order to account for the ability of the butterflies to dynamically change this angle during flight. We then fabricate models of these wings and test them in the wind tunnel at different velocities. The results indicate that the best gliding performance is achieved when the forewings are spread out and the wing span is maximized. In addition, we measure that the gliding performance is increased when flying faster confirming the assumption that a higher Reynolds number leads to a more beneficial aerodynamical regime. We believe that these results are an interesting insight for Biology allowing a comparison of the aerodynamic findings to behavioral observations of live butterflies.