Meeting Abstract
When a flying animal experiences an unexpected change in orientation, its capacity to maintain and restore control is mediated by the complex interplay between wing morphology and wingbeat kinematics. For example, asymmetry in wingbeat kinematics can produce aerodynamic torques at the body, but kinematic asymmetry also redistributes wing mass, which imparts additional inertial torques at the body. If the wings are relatively massive, these inertial torques can be quite substantial. In bats, heavy materials, skin, muscle, and especially bone, of the hand, arm, and hindlimb, were coopted to evolve the wings, which comprise 25-30% of total body mass in our study species, Carollia perspicillata. This anatomical design may be especially suited to allow bats to take advantage of both aerodynamic and inertial torques to perform complex aerial maneuvers, maintain stable flight, and recover from aerial stumbles. Here, we investigated the relative contributions of aerodynamic and inertial torques for reorienting the body following an aerial stumble. We perturbed flight using a jet of compressed air (0.05 N, ~2.5 bodyweights) to the dorsal aspect of one wing, resulting in body roll toward the side of perturbation. Detailed wing and body kinematics of perturbation and recovery were recorded, then projected onto a reduced order 3D dynamical model of a bat. We estimated aerodynamic force using a quasi-steady blade element model, and analyzed the effect of the observed asymmetrical wing motions on the behavior of the model in the presence and absence of aerodynamic forces. Inertial torques from the relatively massive wings contributed substantially to the dynamics of reorientation.
