<HTML><FONT FACE=arial,helvetica><FONT SIZE=2 FAMILY="SANSSERIF" FACE="Arial" LANG="0">Probably the biggest reason for top (or near top) hinging anything is weight savings when using very large ailerons on relatively thick wings as may be the case with AA 3D designs. <BR>
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If 45 degrees of travel is desired, and even if both the aileron and wing are beveled, a quite thick balsa edge is needed to do it conventionally. With top hinging the foam can be cut to the bevel and sheeted with 1/16, having only some 1/4" insets for the hinges. Saves a bunch of weight.<BR>
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As for the gap, on my Widebody 60 with top hinging and very wide bevel on the bottom (actual gaps sealed) there was no deleterious effect. I did tape (front edge only) some 1/64 ply "covers" over the bevel opening and saw no change in upright flight. Nearly crashed in inverted flight as the covers stood up like spoilers in the now lower pressure area (top). <BR>
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Earl</FONT></HTML>