The dynamics of passive feathering rotation in hovering flight of bumblebees

The fluid–structure interaction problem of the flapping wings of bumblebees is considered, with focus on the action of elastic joints between wings and body. Morphological measurements and kinematic reconstruction of the wing motion using synchronized high-speed video recordings are described. They provide the necessary input data for numerical modeling. In particular, for the first time, the moments of inertia of bumblebee's wing are determined using realistic mass distribution. A computational fluid dynamics solver is combined with a dynamical model that describes the wing motion. The model consists of the wings approximated as flat plates, connected with the body by elastic hinges. The results of high-resolution numerical simulations are presented. The hinged plate model produces realistic feathering motion and accurate time-average estimates of the aerodynamic performance in hover, despite some discrepancy in the instantaneous values of aerodynamic forces compared with the fully prescribed model. A parameter sweep reveals that the hinge is not exactly tuned to maximum efficiency during hovering flight, but slightly offset away from the maximum.