Servo Flaps
Thanks for the expanded answer, Dave.
I doubt if the aerodynamic impact of higher speed helicopter flight was on anyone's mind at the time Mr. Kaman pulled out of Sikorsky to start his own company, but the blade pitching moments created at free stream mach numbers above 0.92 have proven to create some problems, and one wonders whether the tie bar design present in the SH-2 design, for instance, is strong enough to prevent destructive behavior. I'm told that when Kaman did a higher-harmonic control system design that went into the wind tunnel, it had a pushrod as well as a servo flap, but that might have been for other reasons.
Thanks,
John