Understanding Bird Flight

Professor Geoff Spedding
Department of Aerospace and Mechanical Engineering
University of Southern California

Date: Wednesday, May 14, 2003
Time: 4:00 p.m.
Place: ENG II, Room 3361

ABSTRACT

The evident success of birds in flight over small and large distances, in confined quarters and also in gusty conditions has inspired admiration, investigation and sometimes imitation from the earthbound human. Birds occupy a range of scales (2 g – 12 kg in mass, and 0.05 – 3 m in wingspan) that overlaps certain micro air vehicle (MAV) designs and there has been renewed interest in whether some bird-like properties (flapping wings, deformable feathers, movable tails) might be useful or even necessary for successful MAV designs. A bird with 5 cm mean chord, flying at 8 m/s has a nominal Reynolds number of 2 – 3 × 104. This is an extremely inconvenient range for design, operation and analysis of lifting surfaces, even in steady motion, because their properties are very sensitive to boundary layer separation. In bioflight, the moderate- to high-amplitude flapping motions, together with the complex surface geometry and mechanical properties of the wings themselves lead to yet further challenges. This talk will review some of the theoretical and practical approaches towards understanding and analyzing the aerodynamics of various types of bird flight, including some recent research results that suggest that this effort is far from complete.