I'm plugging along on my Hummelbird build, and I've hit a snag. I've been working on leading edge fuel tanks in the outer wing sections, which have been done several times before, but there are no plans. I'm a little stuck on building the end caps, the last couple of solutions I've tried to get a minimal gap in the corners have been failures. I've already made the ribs for the middle, but am contemplating a different solution, and wanted to run it by some folks. The original design has a 2" diameter and a 1.5" diameter lightening hole in the nose rib. The outer wing has 7 ribs and is 6 feet long. My thought was it would be much easier to make new ribs with a 4" lightening hole in the rib and insert a cylindrical fuel tank made of aluminum tube. My initial thought would be that this would make the rib too weak, but when you fill that hole, the hole can't deform much. Plus, the skin and spar form a D shape which is fairly stiff on it's own. I don't know how much the lightening holes were calculated or "looks about right" on a design such as the Hummelbird. My reading has not yet covered this detail, and I couldn't find much in the search about it. I could insert more ribs, or make them out of thicker material, if needed. Any thoughts?