Silent owl flight: The effect of the leading edge comb

Abstract

The feathers of owls possess three adaptations that are held responsible for their quiet flight. These are a comb-like structure at the leading edge of the wing, fringes at the trailing edge, and a soft and porous upper surface of the wing. To investigate the effect of the first adaptation, the leading edge comb, on the aerodynamic performance and the noise generation during gliding flight, wind tunnel measurements were performed on prepared wings of a Barn owl ( Tyto alba) with and without the comb. In agreement with existing studies it was found that the leading edge comb causes a small increase in lift. Additionally, at high angles of attack the results from the acoustic measurements indicate that the presence of the comb leads to a reduction in gliding flight noise. Although this reduction is relatively small, it further helps the owl to approach its prey during the final stages of the landing phase.