Does anyone know what makes the Mi-8/17/24 emit the characteristic chirping sound? I found three theories. The first is that it is a rotating drive link on the swashplate. The second talks about the holes for anchoring the blades. The third one, heard and discussed with the lecturer operating the Polish Mi-2 and SW-4 helicopters, talks about the aerodynamics of the rotor, the whistle generated by the blade tips. However, he was not able to confirm it 100% because he is an engineer of the fuselage and engine, not aerodynamics.
Thanks for solving the problem in advance and greetings from Poland
