The single flapping rotor: detailed physical explanations

Abstract A motor-driven helicopter rotor generates a reaction torque. This torque would accelerate the airframe of about yaw axis opposite to rotation if no measures are taken compensate it. In early days development, diversity was considered: Henrich Focke has discussed these different measures. Not well known is compensation measure which restricted only one main rotor, thus skipping tail or any additional as well. principle worth looking into details physical mechanism involved. The German scientist Prof. Hans-Georg Küssner AVA-Göttingen, Germany (Aerodynamic Research Institute with heads at this time: L. Prandtl and A. Betz) first study method successfully. He constructed wind tunnel model showed that could indeed be completely compensated. present author reviewed Küssner’s experimental data show numerical calculations in good correspondence measured results. paper, will discussed. Corresponding presented taking account Navier–Stokes on blade sections. Blade element theory then applied combined data. Calculated forces moments complete four-bladed presented.