by gammaxy » Sun Jan 11, 2015 2:08 pm
Can you share a picture? I suspect the wing would be fine aerodynamically without countersinking any rivets, but doubt anyone has actually tried it (so from your description, I doubt you'd notice any difference aerodynamically). I'd be more concerned that the rivets are fine structurally and would probably only bother sanding them for aesthetics.
Have you tried setting these rivets in a couple pieces of scrap to figure out why they are protruding?