Effect of Wing Kinematics Modulation on Aerodynamic Force Generation in Hovering Insect-mimicking Flapping-wing Micro Air Vehicle

We investigated the effect of wing kinematics modulation, which was achieved by adjusting the location of trailing-edge constraint at the wing-root, i.e., by adjusting the wing-root offset, on the generation of aerodynamic forces in a hovering insect-mimicking Flapping-Wing Micro Air Vehicle (FW-MAV) by numerical and experimental studies. Three-dimensional wing kinematics measured using three synchronized high-speed cameras revealed a clear difference in the wing rotation angle of a wing section for different wing-root offsets. The extrapolated wing kinematics were in good agreement with the measured ones for various wing-root offsets. The Unsteady Blade Element Theory (UBET) was used to estimate the forces generated by the flapping wings and validated by comparison with results of measurements performed using a load cell. Although the thrust produced by a flapping wing with a wing-root offset of 0.20 (c) over bar was about 4% less, its force-to-input-power ratio was about 30% and 10% higher than those with the offsets of 0.10 (c) over bar and 0.15 (c) over bar, respectively. This result could be explained by analyzing the effective Angle of Attack (AoA) and the force components computed by the UBET. Thus, a flapping wing with a wing-root offset of 0.20 (c) over bar can be regarded as an optimal twist configuration for the development of the FW-MAV.