The advice about fiberglassing the skin joint on the outside is really a good one. The foam under the sheeting (skin) has zilch tensional strength. It does good in compression, but where the failure will occur will be where the weakest skin is. All of the flight loads on the wing will try to stretch the lower skin and compress the upper skin (positive g). The reverse will occur in a negative g situation.

If it was my plane, I would not merely trust the fiberglass on the foam to provide the necessary joint strength. Whenever I was racing, I would always add a strip of CF along the max thickness point of the airfoil under the skin, but firmly adhered to it, as well as a wrap around the center section on the outside in order to provide a continuous load path from tip to tip. It didn't add enough weight to make any difference, as I always had to ballast the plane anyway to get it to min flying weight. My pattern planes basically were the same, except I put the CF strips on both the upper and lower skins, since they pulled negative Gs.

Except for one incident where my son closed the wing in the garage door, none ever had a flight problem.

Good luck and good flyin.[sm=tongue.gif]

BTW, I am new to this forum with all the smiley faces. They are kinda neet.

RCS