I added wing tanks in the stubs of my first KR. and did the bottom similar to what you are describing.
Started with the plane upside down. Cut big rectangle out from rear spar to forward spar and put sides and front and back in the area with foam. I made a lip on what was to be the tank bottom about 3/4" to 1" and made sure it was fairly straight and flat on all four sides. Carved additional foam out of top surface of wing so the foam was about a half inch thick there total. Glassed bottom and sides of tank with glass coming up over the sides and folding down on the lip of the tank. Next I took a rectangle of 1" foam a little bigger than the size of the tank and put three layers of glass on it making sure it was nice and flat and smooth. When that cured I cut it to be about 1/8" all the way around smaller than the hole it fit in that I cut out of the bottom of the wing. Then I cut the foam only about another 1/8" smaller so when it was placed on the lip in the tank the glass was about 1/8" smaller than the outside of the lip, I had about a quarter inch gap all the way around the foam, and the glass on my cover overlayed the lip by at least a half inch all the way around. >From there I sanded the inside of the tank and the lip so I could put on more >epoxy to get all the pinholes (I used EZ Poxy back in the days when we did not >have ethanol here, but VE is what I would use now). I used 2" packing tape on >the glass on the tank bottom around the area where it would join to the lip on >the tank. Tank was slathered with a good coat of the epoxy with a lot on the surface of the lip. The bottom was then laid on the lip with the packing tape on the bottom. This was done so that it would not glue the bottom on now, but would fill in any low spots on the lip and make it perfectly fit the tank bottom surface. Weights were put on the bottom plate and epoxy dried. When epoxy was dry I popped off the bottom piece and made sure no pin holes in the tank and lip surface was good and flat. After adding sump to tank bottom plate, plumbing, fuel cap, etc. it was time to permantly attach bottom. Removed packing tape and sanded tank bottom lip area and lip on tank. Used more epoxy and weights to hold bottom down flat. Then I also poured more epoxy around the 1/4" gap around the foam on the bottom piece about 1/4" thick. That epoxy went over the sheet of glass that formed the bottom and around the lip extension so I was 100% sure of a good seal. Filled in the rest of the gap later with foam after expxy was dry, finished off the bottom foam surface, and glassed bottom. ---------- Original Message ---------------------------------- From: John Gotschall <[email protected]> Reply-To: KRnet <[email protected]> List-Post: [email protected] Date: Thu, 20 Nov 2008 07:35:33 -0800 >Now for the fuel tanks.. > > >My engine and panel for N611GB are complete enough to start work on the >20 years of hangar rash and airframe issues. > >I have a few wing tank questions.. > >The notes that came with my plane indicate one wing tank leaks. I don't >know what material was used to make them, epoxy, vinylester, etc. > >The tanks were abandonded by previous owners as the plumbing is missing. >At least one threaded wing fuel cap is missing. > >I was thinking of cutting open the bottom of the wing and taking the >tank bottom out. Then laying up 1 or two layers of light glass and vinyl >ester resin inside the existing tank top and sides. At the same time >replacing the filler necks, caps, vents, etc. Then laying up a >vinylester flat sheet, again 2 layers of bid on something it can be >removed from (suggestions? wax paper??) and later attaching the cured >flat to the tank as a bottom plate (with flox?). Then foaming into >place a bottom sheet of foam, sand to the shape of the wing then glass >over and refinish the bottom of the wings. > >Can anyone point to a site outlining a re-work of wing tanks? Modern >material on old glass? > > >Thanks > >John Gotschall >N611GB >Puyallup, WA > > > > > > >_______________________________________ >Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp >to UNsubscribe from KRnet, send a message to [email protected] >please see other KRnet info at http://www.krnet.org/info.html >
