I started sanding the aileron assemblies today an noticed that they twisted quite easily and were more flexible than I was comfortable with. I know that the covering will help with this (quite a bit actually), but I had trouble with the ailerons in my RV-4 twisting as I shrunk the covering. Since I really like building things anyway, I decided not to leave things well enough alone and added some reinforcing braces. I actually saw this technique used in a old Stella build thread on one of the RC forums (not sure where right now).
I started by cutting some balsa strips from scraps using my handy dandy Master Airscrew Balsa Stripper. This is great tool and makes quick work out of cutting any size stringer out of whatever scraps you happen to have lying around.
Next I added the braces running diagonally in each open bay just under the profile of the rib. I kept all of the braces on the top side running in one direction, then flipped the aileron over an ran braces on the other side in the opposite direction. I was so amazed at the increase in stiffness, that I went ahead an applied the same treatment to the wing. The total increase in weight for both ailerons was about 3 grams. I did not get a before and after weight on the wing, but it would probably not be much more (maybe 4-5 grams) as it has the same number of braces, just slightly longer. All in a dramatic increase in stiffness for a weight penalty of well under 10 grams, not bad.
I did run into on snag when adding the wing braces though. I did the first half of the wing without weighting it down to the building board. I thought that since I was being careful fit each piece without adding any initial tension, that I would not introduce any initial twist and I wanted to be able to flip back and forth as I glued each brace in. Unfortunately, I did end up with a bit of twist locked into the wing, so I had to carefully cut out the braces and start again. This time, I did weight down the wing to my building board and only worked from the top side (working on one half of the wing at a time, of course). This was a little trickier, but resulted in a flat, true, and stiff wing.
I also added another round of balsa filler to the seems on the fuselage and sanded it down with 220 grit followed by 320 grit sandpaper.