I added wing tanks when I converted from retract to fixed gear. In a very condensed form this is what I did:
turned plane upside down cuto out rectangle in wing about 6" from fusalage side to about 18" outboard between front and rear spar glued 1" wide foam rib sections to cap off ends glued 3/4" foam blocks around perimiter with the tops all flat and even about 3/4" from outside skin surface carved out some of the excess foam inside on the top skin surface so I had about 1/2" thickness glassed a piece of 1" foam board about 20" square with three plies, put bagging film on it for a good smooth flat surface cut glassed foam board so it would fit exactly inside the rectangle cut in the wing and rest on the 3/4" foam on the sides glassed inside of new tank area with three plies and 2" extra strips in the corners, glassed over the 3/4" side pieces also covered glassed foam top board with bagging film and put it in tank resting on glassed 3/4" foam supports put weights on perimiter of board to hold it down and make sure that the shape of the dried area on the shelf would exactly match the surface of the board dirlled hole in inboard area of tank and floxed in fuel line installed filler (see below) sanded surface of board and shelf area, cut board 1/8" all the way around sit it was smaller than the hole in the wing cut foam back on board 1/4" all the way around leaving glass extending glued in board and filled in 1/4" trough around it with 1/4" of epoxy for a good seal sanded board to wing shape, filled in remaining trough area and glassed bottom For the fuel filler I used the plastic one that Great Plains sells. It is for boats and has about a 5" plastic disc with a 5" long 2" diamater barbed plastic hose connection molded in. I cut the hole in the wing right through the glass in the new tank and the top surface of the wing with a hole saw. I also cut the 5" hole in just the top surface of the wing. The filler was epoxied in so the top surface of the filler was about 1/16" below the surface of the top of the wing. I floxed it on the inside to be sure it didn't leak and when the plane was turned right side up I filled in some more epoxy that flowed under the 5" diameter to be extra sure there were no more leaks. I cut a block of foam to fit inside the filler cap hole and glassed over the top then cut out the filler cap opening. For the filler cap I laid three plies of glass on a piece of bagging film and stuck the cap on the top. The glass was trimmed when it dried. I wraped a layer of electrical tape around the filler cap and screwed it in before the filling and sanding so it would not get stuck in. I have a fuel pump and a selector switch to select which tank I am transfering from into the main tank. I didn't put fuel gauges in for the wing tanks because I will never let the main tank get under 1/2 before I start to transfer fuel. Let me know if you need me to clarify anything. I guess you could do something similar on the top without turning the plane over but it would be a lot harder. I had to turn it over for the gear anyway. Max Hardberger wrote: >I have had difficulty finding a KR-2 with long-range tanks. Does anyone have >experience with retro-fitting wing tanks to an existing aircraft? > >Best regards > >Max Hardberger >capt...@maritimeatty.com >_______________________________________________ >see KRnet list details at http://www.krnet.org/instructions.html >
