The sweep is about 30 deg. This ensures that the winglet will stall over the whole surface. The aspect ratio is about 3.5, which is less than some of the newer factory gliders. The ASW 27 has an aspect ratio of 4.7 . Due to the large HP18 wing tip chord, which is 18", the height of the winglet is nearly 24" above the top surface of the wing. The ASW 27 only reaches 20". The search for an airfoil came by way of model glider airfoils. I picked one that came closest to the airfoil polar required for a winglet and simply changed the camber and thickness ratio slightly to match the polar. (See article of Mark Maughmer in Technical Soaring and Peter Masak article in Free Flight