Help !!!!
Nick, you asked the question "Is this really that complex??" and the answer, at this point in time, is yes. That is why my former post has been replaced with this one,
You say; "If the rotor flaps faster, the flap occurs sooner in the rotation, so the rotor phase needs fewer leading degrees.". The answer here is also yes, if the rotor flaps faster. However, I see nothing that will cause the rotor to flap faster. Any advantage derived from delta-3 in one 90º sector [blade returning from maximum + or - flap] is a disadvantage in the next sector.
From my current perspective, there are two possible scenarios.
~ One is as you say. The amount of angler flap within a single revolution equals the angular difference between the control plane and the tip path plane. There is nothing left to be done in the remaining 18º and Lu is up the creak without a paddle.
~ In the other, the amount of angler of flap in a single revolution equals the angular difference between the control plane and the no-feathering plane. In this scenario, it takes a number of revolutions for the control plane to become coplanar with the tip path plane. Therefore something must be happening during these 18ºs and Lu has a point. This is the same argument that I made in my previous posting, but in different words.
Currently, I tend to favor the latter.