I retrofitted them in the stub wings at the same time that I converted from the retract gear to fixed gear. It wasn't terribly hard and doing it on the outboard wings should be easy also. Basically here is what I did:
Cut a rectangular hole on the bottom side of the wing between the two spars. Use foam sheet about an inch and a half thick aginst the spars and on the inboard and outboard side of the hole you cut. You basically want to make a box in the wing and leave a lip around it that is flat and about 3/4" below the bottom surface of the glass on the wing. Carve some of the foam out of the wing top sheet to give yourself a thickness of about 3/4" on the foam. Use some instant expanding foam to give yourself somewhat sealed corners and make them a little rounded. Now get a flat sheet of 2" foam a little bigger than the rectangle you cut out and glass one side of it with three layers of glass. Lay it upside down on a flat smooth surface with bagging film or plastic sheet on it and put some weights on it so when it dries you peel off the film and have a foam board with one side of smooth flat glass. Trim this piece so it is about an eighth inch smaller than the hole in the wing all the way around. Wrap it with bagging film or plastic wrap. Now cut yourself three layers of glass to fit each of the bottom and sides of the box hole in your wing. Make them all a little big so they overlap on the edges and make the side pieces tall enough so they wrap over the flat lip you left on the side pieces. Also cut a bunch of pieces of about 3" strips for reinforcement on all corners. Glass all the pieces in overlapping and also putting the strips between each layer in the corners. When it is all in you will have the glass folded over the lips around the box. Get a good amount of epoxy there and then lay in the foam and glass rectangle that you made and wrapped with the plastic. Put some weight on it around the edges. When the tank dries you will be able to pop this piece out and the lip on the tank will be nice and flat and fit the rectangular cover. Now trim about a quarter inch additional off of the rectangular piece. Sand the edges of it and the lip on the tank for a good bond and then epoxy it in. You should have at least a half inch of contact area between the surfaces. Put weights on the edges then pour some epoxy about a quarter inch deep around the edges to get even more of a seal. This is why you trimmed it again to make yourself the epoxy moat. When it is all dry you can fill in the gaps with expanding foam, sand your rectangular cover foam to match the wing, and put on another two or three layers of glass overlapping the original glass on the wing. I did leave out a few steps like putting in the fuel lines etc. Make sure you have some kind of screen on the end of the line. I also carved a concave well in the front inboard side of the cover where the fuel line pickup would sit and one in the rear inboard corner where I epoxied in an aluminum welding flange for the sump drain. I also epoxied in one of the plastic fuel caps that Great Plains sells before I put the bottom cover on. I used a good bit of expoxy on the inside of the box and still had some pin holes so I sanded it down then used a brush to paint on a good wet coat of epoxy and let that dry to get it sealed. Since the bottom cover dried against the smooth bagging film it didn't have any pin holes. Good luck. This process is a whole lot harder to describe than it is to do so if you don't get something I am saying just ask. You can also cut the hole in the top of the wing, but it is much less flat and will be a lot harder to make the cover for and have it seal against the rest of the tank. I used three layers of glass in the tanks. Mine were only 5 gallons each. If you are making them bigger you might want a little more glass at least on the bottom and sides. Brian Kraut Engineering Alternatives, Inc. www.engalt.com -----Original Message----- From: krnet-boun...@mylist.net [mailto:krnet-boun...@mylist.net]On Behalf Of D F Lively Sent: Thursday, March 09, 2006 9:48 PM To: kr...@mylist.net Subject: KR> Retro-fitting Wing Tanks KR Builders. Has anyone retrofitted fuel tranks in the outboard wings? What about "Bladder Tanks"? Don Lively riksh...@interl.net _______________________________________ Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net please see other KRnet info at http://www.krnet.org/info.html
