The upper wings are of the “candy-bar” design, i.e. they are not tapered towards the wing-tip.

Using the Goettingen airfoil, I have drawn the top wing in CAD.

I then cut out the wing ribs. I did this with a scroll-saw for the ply wood parts, and with a scalpel for the balsa parts. If you do not have a scroll-saw, you can use a fret-saw, a hacksaw, or practically any other saw. cut 1 or 2 mm outside the line, and sand down to the line for the best results.

Finally, I  glued it all together using white wood glue. I prefer this glue for spruce, as it penetrates into the wood and gives a stronger joint than i.e.cyanoacrylate (superglue).