The currently designed rotor (sketch D) will offer better control but it will also exhibit vibration at large displacements of the cyclic stick, when the tip path plane is not parallel to the rotor mast plane. This is due to the 2P change in the tipping moment on the mast, as the 2-blade rotor rotates.
[described in blue above.]
It looks like the following is a solution to this vibration problem.
The hub in sketch D is now to be constructed as a 3-blade rotor, instead of the previous 2-blade rotor. The former tie-bar between elbows of the two yokes is now replaced by a triangular tie-bar, which connects the elbows of all three yokes. This means that the roots of the three blades teeter (flap) in an interlocked unison.
Temporary Coriolis (Hookes Joint Effect), will now input a lead-lag between the three blades as they flap.
But, delta-3 by flap hinge geometry also inputs a lead lag into the blades as they flap. Therefor the angle of the delta-3 can be set so that the amount of lead at a specific angle of teeter (flap), due to the Hookes joint effect, can be absorbed by the same amount of lead input by the in-plane component of the delta-3 angle.
In other words, as the blade flaps up, the delta-3 will absorb the Hookes joint's lead and as the blade flaps down, the delta-3 will absorb the Hookes joint's lag.
Sketch of rotor hub.
If anyone is still reading this thread and can find fault, please say so. Thanks.
Dave J.