Brian: My biggest concern was weakening the wing by cutting into it. I am also toying withe the Idea of a "Bladder Tank because the tank would collapse as the fuel was consumed whch should reduce the tank venting issue. My goal is to reduce the fuel in the cowl header tank to about an hour and have the rest in the wings.
How did you reinforce the wing to make up for opening the wing? I feel also that a properly designed bladder tank would require a much smaller opening which should be a plus but fuel "slosh from lack of "baffles" could be an issue. I am taking over a KR2 project that was being built as a Tr-Geared bird and is on its main gear. It needs Fire-Wall Fwd, Nose Gear ass'y and cockpit fit-out pait and finish. I intend to do all that I can to get it under sport-plane limits so it will have a smaller engine in it to keep the Speed down. Max fuel load will be kept to no more than 21 gallons usable but not less 5 hrs range. I want it for cross country use from my midwest location to Yuma in the west and Raliegh Durham in the east. Shoud make for cheaper travel than by car and a whole lot quicker. I am a Pvt Pilot with over 300 hours but at age 63 will just convert to a sport pilot. Don Brian Kraut wrote: > 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: [email protected] [mailto:[email protected]]On > Behalf Of D F Lively > Sent: Thursday, March 09, 2006 9:48 PM > To: [email protected] > Subject: KR> Retro-fitting Wing Tanks > > KR Builders. > > Has anyone retrofitted fuel tranks in the outboard wings? What about > "Bladder Tanks"? > > Don Lively > [email protected] > > _______________________________________ > 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 > > _______________________________________ > 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
