I have just printed off the root rib and tip rib for a new model,the tip
rib is thicker on the rear section,see attached scan,I have always
sanded the wing down so it tapers in a straight line to the tip rib,have I been doing it wrong?
Should the tip rib remain thicker.
The root rib is on top of the tip rib to show the difference.
Thanks

   The drawing is shown below, in a viewable format...

   I am not sure what we are looking at here, is this supposed to be a constant-chord wing?  If so, the "outer" aft section is not even faired into the rest of it, it has a distinct discontinuity where the extra section joins the rest of the shape. That is almost certainly not intentional, even if if there was supposed to be more curvature in the aft part of the airfoil. It will make for a very odd-looking wing, but the lack of "fairing" will disappear with a few swipes of the sandpaper.

  If this is just a notional drawing of the tip rib, it's possible that it is intended to have more curvature at the tip, either on purpose, or it just worked out that way when the designer drew around his shoe.

   If intentional, whether it is important or not is debatable. There is a school of thought to make the tip airfoil section proportionally thicker or somehow different otherwise, to avoid the dreaded "tip stall". Avoiding "tip stall" is an entirely moot point for stunt planes, because you can't ever operate successfully while stalling at all. There may be other, more important reasons for the tip airfoil to be different, but those are debatable as well, and most of the arguments I have heard about corner exits, etc, are pretty hand-wavy.

    Brett

Brett
         Its a tapered wing,I had the root rib on top of the tip rib just to show the difference and the wing has
a straight trailing edge,as you said a few rubs of the sanding bar,which is what I have done in the past,
thanks for the reply.

  OK, now I see, most of what I said above assumed something else. This is not a terribly unusual situation, if the designer made the tip proportionally thicker.

      Brett