Meeting Abstract

21.3  Sunday, Jan. 4  Pitching, Deformation and Control in Insect Flight BERGOU, A.J.*; RISTROPH, L. G.; COHEN, I; WANG, Z.J.; Cornell University ajb78@cornell.edu

The complex wing motion of a flying insect is due not only to muscular activation but also fluid, inertial, and elastic forces. Thus, it may be that not all aspects of the wing motion are actively controlled by the insect. As with conventional airfoils, the orientation of a wing to an oncoming flow, otherwise known as the angle of attack, is an important kinematic parameter for a flapping wing. Even small changes in this angle can drastically change the forces a wing experiences. Additionally, wing pitch reversal, the sudden change of angle of attack at the end of a stroke, represents an important difference between flapping wings and a continuously rotating blade (e.g. helicopter flight). Here, we ask whether changes in the angle of attack of wings of flying fruit flies are modulated actively by insect muscles, or do wings turn over passively like the fluttering of falling paper. By applying a three-dimensional reconstruction technique to high-speed films of flying fruit flies, we are able to image an elastic wave on the wings whose direction of travel indicates passive pitching. To further analyze passivity of wing rotation, we extract the detailed wing kinematics of flies using a novel motion tracking algorithm and compute the forces acting on the wings. Finally, we infer whether flapping flight is possible without pitching control.