Analysis is straightforward but big. Spar carries shear and bending - do initial sizing by standard beam theory. Wing skin plus spars carries torsion - You could size the skin just to carry torsion, but everybody uses 2 UNI at +/-45 deg plus 1 UNI lengthwise or something close to that for the outside and 2 BID or 2 UNI at +/- 45 deg for the inside of the panel, so start there because you will probably end up there just to have a wing you can build and handle. Skin panels carry airloads where the skin is broken into panels by main spar/ ribs/ auxilary spars/ other stiffeners. The skin ends up having several things happen simultaneously: Whole wing bending deflection (compression on one skin, tension on the other); Whole wing torsion deflection (shear on the skin), and; Panel deflection form air loads. Once you have the various system stiffnesses together (composities mechanics is a lot of matrix math) and the oddball skin buckling fuss, you need to determine each of the load cases, turn the crank to determine the system deflections, lamina deflections and check against failure criteria. The initial design will fail the shear web, and maybe some other stuff too. You have several paths to pursue to make it strong enough and then to minumize weight, but it will be a blend of beefing up the main spar caps, main spar shear webs, and decreasing the rib spacing. A seriously multivariate problem.

The composite mechanics is a graduate class in mechanical engineering with prequisites in solid mechanics and matrix mathematics. The optimization is a designed experiments problem. I have all of this in my background, and I understand it. If you do too, you can work your way through the composites texts and understand what you are doing and maybe even have some fun with it. Yeah, I am a geek. Maybe you are too. Grin.

For little airplanes (Even the Rutan Voyager has the non-fuel tank sections built this way), the surfaces are lighter with just a solid core skinned on the outside. The weight savings from removing some of the foam is offset by the weight of the fiberglass skin on the inside, the fiberglass/foam ribs, and the adhesives and tapes to couple them together.

Billski