This posting completely replaces a previous posting that was totally wrong.
Lu,
It looks like Nick got us, again.
Delta-3 is a little more complex than we thought. Wayne Johnson in 'Helicopter Theory' explains it in depth, using some weird language called mathematics. He also, very kindly, explains it in the single embarrassing sentence;
"Thus pitch-flap coupling introduces an aerodynamic spring that increases the effective natural frequency of the flapping motion ...."
OOPS. Perhaps a dozen pieces of metal in a delta-3 hinge do have a higher cognitive ability we do.
Nick,
You are right. Thanks for the knowledge and for taking the time to drive this to a correct conclusion.
