BISHOP, K.L.; Brown University: Kinematics and performance in two species of mammalian gliders, Glaucomys volans and Petaurus breviceps

Gliding has evolved independently in at least six lineages of mammals, all resulting in similar morphology and behavior. Investigations of the relationship between kinematics and gliding performance can provide insight into the mechanics of mammalian gliding. In addition, a comparison of gliding performance as it relates to kinematics between distantly related groups of mammals can reveal possible functional constraints on gliding behavior within mammals. In this study I compare the 3D kinematics and performance of two distantly related, but similarly sized gliding mammals: the placental southern flying squirrel (Glaucomys volans) and the marsupial sugar glider (Petaurus breviceps). The animals were trained to perform short glides along a known trajetory and were filmed from below during mid-glide using two high-speed digital cameras. Reflective markers were used to identify anatomical landmarks and the 3D coordinates of these points were computed using direct linear transformation (DLT). From the 3D position data I computed aerodynamically signifiant kinematic features such as angle of attack, camber, and instantaneous projected area of the wing and related them to performance measures such as glide angle, velocity, and body rotations. I also used the position data to compute the vertical acceleration during mid-glide, allowing me to estimate the lift and drag generated by the animal and examine how differences in body position coincide with differences in aerodynamic force. Comparison between the results of this study and predictions based on aerodynamic theory highlight the differences between the aerodynamics of low aspect ratio, flexible, extensible wings operating at a moderate Reynolds number and the wings of large, fast moving, rigid-winged aircraft.