The flowfield surrounding wings with a pure flapping motion was studied in quiescent air at a Reynolds number of approximately 200 using particle image velocimetry (PIV) in unusually thin illuminated planes ( 0.3 mm). Typical wing semispans were on the order of a few millimeters. The polymer cantilever wings consisting of monodomain liquid crystal polymers made from azobenzene (azo-LCN) were flapped at 30 Hz at a large amplitude (>170 ). Chordwise and spanwise planar slices of the flow across the wings were obtained and used to estimate the unsteady aerodynamic forces generated by the...