Hey, don't destroy the good flight characteristics with that undercamber wing, both high lift and slow flight positives. Take some thread and stretch, sew, knot and glue it from leading edge to trailing edge if you want to "reinforce" the wing structure, but don't make it into a "Clark Y" by sheeting the bottom!

Here is a beauty I fly with undercamber, vintage 1911. Can't not stall it! It is probably the most realistic to fly model compared to a full size airplane that I have flown, perhaps because it can fly so slow. Absolute, fantastic contollability at all speeds. Easily have more than 300 flights on it!

Yep, it is an "ARF' because someone else built it and I am the third owner.