To: Dave Jackson
“This coupling tends to restore the pitch in the blade moving forward and takes pitch out of the blade moving backwards very much like a tail rotor”.
This [teetering] coupling (i.e. delta3) removes pitch from the blade that is teetering up and adds pitch to the blade that is teetering down.
We are both saying the same thing. The blade moving forward has pitch added to it by the pitch coupling and the blade going back has pitch subtracted from it.
My comparison to the tail rotor was incorrect, as it is the opposite of the main rotor. The advancing blade because of the oncoming air loads, will flap out, and in the process will have pitch taken out of it. The retreating blade, which is moving with the relative wind and is mechanically connected to the other blade, will flap in and the delta hinge will add pitch to it, which equalizes the lift across the tail rotor disc.