Mark Henderson
Well Known Member
Back in May a couple of people commented on the necessary clearance in the side skin for the main spar. The consensus seemed to be that 1/32 or so would be adequate. Before I installed the side skins I made sure that the skin slid over the rivets on the spar without hanging up. I had about a 1/32 or so, and it was not a problem sliding the skin over the spar. Yesterday I had a chance to try the fit in more real conditions.( I am building in a full size hanger so room in not an issue.) It was difficult to keep the wing at 90 degrees to the cutout in a hanger.It does not take much error on the part of either person for the spar to hang up on the skin. I had the doors open and we were hit with a couple of gusts. This made it even harder to keep from rubbing on the side skin. If we had been doing this on the ramp I suspect we would have dented the skins because the wing has too much surface area. In looking at the design, I can see no reason to make the tolerance this tight. I think 1/8" is more reasonable. The wing has a seal of sorts around the root. If there was any wind noise, you could fashion a donut around the spar that presses up against the cutout.
