To: TIMTS
Hopefully this does not set me up for a lot of critical comment. The Delta or difference is the relationship between the pitch change axis of the tail rotor and the flapping axis of the tail rotor. This difference depending on the design can range from 30-degrees to 60-degrees. The delta hinge or flapping axis is offset which allows the tail rotor to rock across the flapping axis. In the process of rocking one blade will move in toward the fixed pitch link and in doing so pitch will be removed from that blade. Conversely when the blade moves away from the fixed pitch link pitch will be added to that blade. This gives the tail rotor the ability to equalize the lift across the tail rotor disc. This is similar to pitch flap coupling on the main rotor system. As a blade is moved upwards due to gusting which raises the blade from the commanded tip path the blade moves away from the pitch link and pitch will be removed from the blade allowing it to return to the commanded tip path. As the blade drops down into the commanded tip path the pitch angle of the blade will return to the commanded (Collective / Cyclic pitch setting).
Awaiting all comments.
To: SASLess
One of the illustrations in your reference shows the pitch horn / pitch link coincident with the flapping hinge. The description states that with the pitch link in this position there is no delta hinge effect when the blade is flapping. This is true if the blades were static and you lifted one blade. In actuality when you add collective pitch the two points are no longer coincident but the pitch link will rise above the flapping hinge and with the blades dynamic gusting will result in pitch flap coupling (delta hinge effect).
