Originally Posted by
Al M
The static stiffness of the blades is likely irrelevant. Once centrifugal force is applied due to rotor rpm the blades become really stiff.
Yes to that. Soon after signing in at SA in 1966, one of the senior handling qualities engineers, Dick McCutcheon was talking about this subject and related some findings in a test done on an S-58, to wit, that the tip response to a collective input would result in a transient overshoot of the tip path, relative to the new tip path trajectory, whereas a cyclic input did not. That sounds counter-intuitive doesn't it and when I remonstrated with Dick, he gave me the legendary Igor Sikorsky advice about what to do when the facts and theory disagree!