Approximate analysis for main rotor flapping dynamics of a model-scaled helicopter with Bell–Hiller stabilizing bar in hovering and vertical flights

In this paper, the effects of the rotor flapping dynamics in the control design for the model-scaled autonomous helicopter are analyzed in detail. The analysis is based on a specific model-scaled helicopter equipped with a Bell–Hiller stabilizing bar. A simplified analytic model for the flapping dynamics in hovering flight mode is derived and then expanded to the vertical flight mode. Eigenvalues of the approximated linear system indicate that flapping dynamics in both flight modes is comparatively fast and asymptotically stable. Effects of the rotor dynamics with Bell–Hiller stabilizing bar are assessed with both simulation and experimental results, indicating that static approximation of the rotor dynamics in control design is acceptable.