The physics of flight: II. Flapping wings

摘要

In any conventional aircraft the wings provide the lift and the engines provide the thrust. In a bird, however, the wings have to provide the thrust as well as the lift. In this article we shall use the ideas presented in the first article of this series to develop a simple theory to explain how this comes about, and use it to predict some important characteristics of the flight of birds, including their wingbeat patterns and their minimum power requirements.