At-scale lift experiments modeling dragonfly forewings.

An experimental investigation of the lift performance of an artificial platform at the scale of the dragonfly species Sympetrum sanguineum is presented. The platform, as well as the lift sensor, was custom designed and built. The flapping mechanism consisted of a piezoelectric bending-beam actuator, a transmission using carbon-fiber elements and polymide-film joints, and wings constructed of polyester film with a carbon-fiber support structure. The flapping kinematics of the Sympetrum sanguineum was replicated as closely as possible although only a pair of forewings were used in these experiments. The lift generated, when accounting for the addition of a pair of hindwings, is predicted to be sufficient to allow for the hovering of a dragonfly. The results, the first at-scale fully transient measurements of artificial dragonfly forewings, show that the lift curves quantitatively as well as qualitatively validate existing two-dimensional and three-dimensional computer simulations of dragonfly forewings.