Lu,
It is not a pitch instruction that is telling the blade to flap. It is an outside force (gusting) that the blade is responding to and not pitch input from the pilot.
Who cares whether a gust moved the tip-path plane off the control plane, or the pilot moved the control plane off the tip-path plane?
In both cases, the end result is that the blade (tip-path plane) will teeter toward the position dictated by the cyclic (control plane). All that delta3 does is effect how this realignment of the two planes takes place.
How come I'm getting a sense of déjà vu?
