PBL...
You are now allowing that maybe some of the lateral surface is relevant to reacting to sideslip (or yaw, depending on which axes you are measuring in). That is progress of a sort.
Let me suggest you accept what ImbracableCrunk said right at the beginning, and what aerodynamicists have said in text books (which I have quoted), and what they say when one discusses it with them. The VS is there for a purpose. Someone put it there. They know why they put it there, and it works, over decades of experience. So when they say why, and how, I imagine there would - should - be a strong inclination to believe them, no?
What I've said from the start, in different ways, is that while in a banked attitude, the entire tail section (vertical stabilizer/rudder and horizontal stabilizer/elevator) controls yaw (and pitch) partially, either eliminating unwanted yaw (coordinated flight), or producing yaw (slip/skid). It's a function of your bank, the more bank, the more the rudder controls pitch and the more the elevator controls yaw. A V tail aircraft is a perfect example of what I mean.
I think we're talking about something else. The VS is there for stability. I'm not contesting what a VS is used for. Your second paragraph is quite confusing to me, I don't understand how it applies to the discussion on weathercocking while in a turn...
If it is correct that the aircraft is weathercocking while in a turn, then my reasons for why it does not should be false and I haven't seen anyone clearly disprove what I've been saying. I'm completely open to different ideas but I think firstly you have to clear away the false information and then start with a fresh slate to explain a concept or theory.
EDIT: PBL are you talking about this quote from IC?
Make an airplane with your right hand
Palm down
Fingers together
Bank your airplane 30 degrees to the left
Slide your airplane hand to the left due to the now horizontal component of lift
Take your left index finger and push on your vertical stab
Watch your airplane magically weathervane
I already addressed that. What he described was an aircraft in a slip and the tendency of the aircraft to "weathervane" into the wind because of the crosswind component on the tail section. I completely agree with this! But I don't see this happening while in
coordinated flight!