StumbleI went back to the spadflyer site and clicked on the left hand picture. This brought a closer veiw of the wingtip and there are sub ribs in the picture to help form the rounded airfoil. Plus in the pic you can see they cut several of the flutes on the inside skin so the plastic would roll over. Plus one flute behind the spar. If I build anothet SPAD I will give that a try with a 4mm wing. It would be nice not to have to hunt down 2mm sheeting.