I like this photo which shows: crimped-edge, junction of 4 skins, flush pop rivets (dimpled not countersunk), and of course the incredible polish; thus, the selfie of my camera.
I assume we are seeing the juncture of 4 skins overlapping where the wing tip joins the wing (looking from the aft of the wing). One can see the tent reflected in the wing distorting the image. Aaaagh!
Grand Champion - Ultra Cruiser ... high polish and excellent workmanship. .016 aluminum is to thin to polish without fear of dents and kinks. The polish was achieved by polishing the alumunum BEFORE cutting and assembly of the parts.
