Just a quick question that I should already know the answer to...

When centering the control surfaces on an airfoil shaped surface for an elevator or rudder should the center of the trailing edge of the surface be even with the center of the trailing edge of the horizontal stab or fin?

When centering a straight, blocky control surface I know you can take a ruler and make sure the underside lines up but with the taper in an airfoil shape it doesn't make sense to do that.

take a ruler on the profile of the shape and line it up front to back of the airfoil this line will give you the center point for the moveable surface

on a tapered control surface, I eyeball it until it looks straight. If you have a deflection gauge, you can use it to center the control surfaces.

Without a guage, you just have to eyeball it. Only by flying it will you know for sure.

You have to use the profile of the surface and not the edge of the surface.

a deflection guage will tell you nothing about the centerpoint of the surface. It only tells you the amount of deflection away from center.