RE: Building a full flying stab for my SU-27
You could glue the rod into one stab half, and hold the other half on by using a screw, threaded into a piece of hardwood or ply that's glued into the rod...? I wouldn't trust a "friction fit" on an IC engine powered plane... those vibes will get you sooner or later!
I agree with Troy though... put your pivot point a little more to the rear... your servo is going to have a hard time if you build things like in that drawing.