.... 22 09 1994 ©The Company of Biologists Limited 1994 bird flight emarginated feathers induced drag non-planar wing primary feathers soaring span efficiency factor tip feathers vortex diffusion vortex spreading winglets Harris’ hawk Parabuteo unicinctus Most birds...

... is wing span and q is the dynamic pressure: where ρ is the density of air. 5 3 1993 © 1993 by Company of Biologists 1993 bird effective aspect ratio effective span flight flow visualization free vortex emarginated feathers Harris’ hawk non-planar wings Parabuteo...