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Q-talk 96 - Wing Tips

Enid, OK

This picture of my 8" wing tip shows an access hole in the bottom. I wanted to make the wing tips removable with a flange glued to the inside of the canard and wing. The end of the wing tip is tapered and too narrow to split in half, so I shaped the wing tip first (out of urethane foam 5 min. to the wing) and tapered it. Then I rolled the end up for a conservative "winglet". I popped the urethane loose from the wing and covered it with "duct tape". After glassing up the shape with 5 BID and flox dams in the sharp or thin areas, 1 side at a time and removing the foam and "duct tape", I marked an access hole that is about 12" X 3". Before cutting the hole, I covered the inside area of the wing tip with duct tape and laid about 3 plies of BID over the area that would become the access hole. The bid covers an area about an 2" larger than the access hole (be sure to leave 1 1/2" from the inside edge of the wing tip as the flange coming from the wing needs a 3/4" lip to connect.) After the bid cured, I clecoed the BID flange in place. When I popped off the BID flange, I marked the area for the opening and cut out the access hole. I then clecoed the bid flange back in place and marked a lip 3/4" inside the cut out for a flange to set the cut out piece back into place. After cutting out the marked opening in the flange, I then clecoed the cut out back into position. At this point I set the cut out and flange aside. I then proceeded to Dremel out 2" of foam in the wing and remove the micro from the inside of the wing lay up so that I could have a glass to glass lay up inside. I made the inside foam surface flat so that I could later close out the wing with 2 bid of glass and a radius in the corners with flox. I covered the inside of the wing tip with duct tape so it would pop loose from the lay up.

Then using 5 minute I bonded the wing tip onto the wing or canard with cut up stirring sticks. At this point I cut out 5 BID strips for the top and bottom of the wings and tips. I layed up the 5 layers on top of each other onto plastic wrap. I then cut around the plastic wrap to lay up the BID strips inside the wing (through the access hole) and onto the wing tips (multiple layers are easier to handle all at once rather than 1 at a time). Be sure and "wet out" lay up area before you apply the BID strips so you don't have a bubble anywhere. After the inside flange on the wing cured, I popped the tip loose and realigned the top with a straight edge and clecoed the wing tip in place. You are then ready to remove the "duct tape". It helps to use peel ply on things, as it will be faster when you close out the end of the wing. After attaching the nut plates and drilling out the screw holes for 10-32 tapered holes you will have a removable wing tip. Oh, you might want to trim the flanges and flox the access hole flange and cover closed before attaching the nut plates, as things tend to drift with every fitting. Use some old clecos and soak them in Acetone when finished so you can reuse them Who knows, you might want to change to a different tip length some day. With the removable tips, you can do just that.

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