RE: Wing Dowel Question
I should have mentioned that the dowel was for the leading edge. I've always used a front dowel with nylon bolts on foam wings. I don't like using rubberbands on any model because of the mess and the way that balsa can be crunched by them on the surface of the wing. I used a dowel on an 84" span American Eagle Spitfire with no retracts that came in at 13.5 lbs. With a fiberglass fuselage and foam wing, there just isn't much to the airframe that adds weight. I used Solartex and Rustoleum to finish the plane with no surface detail. The wing took quite a bit of abuse including a landing in tall grass that spun the plane sideways with no damage. I only used cloth at the center and didn't put in a spar. I couldn't remember the size dowel that I used on the plane. The plans that I am using now are for a built up wing with a tab drawn from the leading edge but give no other dimensions. I got a foam wing cut because they are easier and quicker to sheet and to get a straight wing.
Gorilla glue works really well with foam. It is the consistency of syrup and easily fills voids. It expands 3 to 4 times in volume as a foam in an area that is not clamped while drying and has a hardness that is difficult to sand. What I have done before is drill a hole that is larger than the dowel and then sand the hole larger at the leading edge down to the foam with a bevelled angle. Put tape on areas that don't need glue on them, and partially fill the hole with glue. Then slide in the dowel and wipe away any glue that may get close to the top. The glue then foams over the top while drying and must be sanded away to the shape of the leading edge. The dowel is then in a substance that has a larger contact area with the foam to better resist crunching it as compared to a slip fit. There have been times where I didn't get a flat surface while sanding in dihedral. The glue worked very well in filling the void.
Here is a picture of the plane. It is kind of a pieces parts kit with the fiberglass fuselage purchased from one source, the wing another, and the plans and canopy from another. The wing isn't mounted yet. The tail surfaces are balsa. The vertical stab is sheet balsa, the horizontal stab, evelator, and rudder are built up.