Short Communication The moment of Inertia of Bird Wings

Abstract

ABSTRACT The moment of inertia of a wing about its proximal end must be known in order to calculate the inertial torque and power required during flapping flight (Ellington, 1984) and it is also one of the morphological features that affects flapping frequency (Pennycuick, 1975, 1990). At present, however, there are very few data on wing moments of inertia of flying animals and thus there is no way of predicting the wing moment of inertia of a flying animal from easily obtainable morphological measurements. Arguments predicting bird wingbeat frequencies (Pennycuick, 1975), following Hill’s (1950) argument that the maximum frequency of a vibrating limb is set by the mechanical properties of the muscles and tendons that accelerate and decelerate the limb at each end of the oscillation, have assumed geometric scaling of wing moment of inertia about the shoulder joint. The objective of this study was to determine if the wing moment of inertia of birds does indeed scale geometrically or, if not, how it actually does vary with body size.