RE: Knife edge tucking
these images show what I was tryin' to 'splain!
image 1 shows the model in the flow domain...
images 2-5 just show the model itself
image 6 shows a closeup of the flow vectors over the aft region of the tail....
you can easily imagine a line along the fuse side that marks the "Stagnation" point.
If the stab is high, the induced flow creates an AOA that causes the stab to lift up, thus pushing
the nose down....
if the stab is low, the induced flow creates an AOA that causes the stab to lift down, pulling the nose
upward.....
As a test simulation, I placed the stab on the wing CL, cut the model on that plane, and mirrored it on that plane
to verify the simulation resulted in a net zero coupling... it did.