A Wind-Tunnel Study of Gliding Flight in the Pigeon <i>Columba Livia</i>

TLDR

The study develops a tilting wind‑tunnel protocol to train pigeons for gliding flight and introduces a method for measuring lift and drag. Drag was quantified on wingless bodies and preserved feet in the wind tunnel, enabling decomposition of total lift and drag during gliding. Analysis revealed that as speed rises, pigeons shorten wing span, area, and aspect ratio, increasing induced drag but greatly reducing wing‑profile drag, so the lift‑to‑drag ratio remains near its maximum (≈5.5–6.0) up to speeds at least twice the minimum gliding speed.

Abstract

ABSTRACT A technique for training pigeons to fly in a tilting wind tunnel is described, and a method of determining lift and drag in gliding flight is explained. Drag measurements were made on wingless bodies and preserved feet in supplementary experiments. The results were used to analyse the measured total drag of live pigeons into (a) body drag, (b) foot drag, (c) induced drag, and (d) wing profile drag. As speed is increased, gliding pigeons drastically reduce their wing span, wing area and aspect ratio. The increased induced drag resulting from this is more than offset by a very large reduction in wing profile drag. Although the lift:drag ratio is at best 5·5-6·0, changes of wing area and shape keep it near its maximum, up to speeds at least twice the minimum gliding speed.