Help with fuel tank replacement - 1992 KFIV Speedster

[Bob Brocious]

Folks,
I got my new 13 gallon tank from Kitfox, removed the right wing and put it in my basement to begin work. I've never done this kind of work before ... remove old fabric, remove old tank, replace with new tank, recover. I'm anxious because I want to do it right and well.
I can see a tape seam around the old 13 gallon tank. Two of the seams are on ribs that box the tank in. The other two seams appear to be where the two spars are located. I think I have to remove the fabric to at least the middle of each seam in order to get the tank out.
I probably should mention that I plan to use Oratex to cover this hole up. I've talked to Lars and he said that Oratex can be used to patch over poly fiber.
How far should I cut the old fabric back?

P.S. Found something odd on this old tank. It appears that whomever installed this tank originally didn't like the location of the filler neck. So they sealed it up with bondo (?) and added a new neck. The material used to add the new neck is probably the source for my original problems of finding huge pieces of sticky material in the tank!
Tank1.jpg
tank3.jpg
tank2.jpg

Thanks for the help and support.

[jiott]

If it was me, I would replace the whole top wing panel over the tank bays, rather than patch the area you outline in red. Then all my new fabric seams would be over ribs, front spar, and trailing edge. this would also make the new-to-old paint transitions much less noticeable.

Also, I question using an Oratex patch. Oratex is normally not painted, but getting an Oratex color to match your old paint will be nearly impossible.

[Bob Brocious]

Jim, what are you referring to when you say "replace the whole top wing panel over the tank bays?" Do you mean going all the way to the trailing edge and up to the leading edge? Where would I stop on the leading edge? How close to the trailing edge should I go? Does this picture illustrate the area you are talking about?
Attachment 12123

I understand that color matching will be a challenge but ... they have a white that is very close to this that I can live with.

[Dave S]

Hi Bob,

In your query you indicated you want to do it right and well. With that in mind, I'd throw out a couple thoughts, particularly since this is your first try at it.

1) I'd echo Jim's comment about not mixing covering materials. If you know it has polyfiber covering, your best results will be with using polyfiber products to do the repair. If not polyfiber - go with whatever the original installation has.

2) Polyfiber publishes a manual including repair procedures for use of its products.....it's a plain language real life document that is easy to understand. If you are using polyfiber - get the manual - reasonably priced and well worth it - it will answer all the little how to issues with a repair.

3) If you have not covered a Kitfox wing before - completely or in part. Be aware that there is a procedure using polybrush to assure the fabric bonds to the top of the new fuel tank.

I don't want to guess how far you would need to strip the fabric - as Jim said you want to go back to a good hardpoint.....if the fabric is in good condition you should not have to do the entire wing....on the other hand - if its in bad condition - a complete recover might be something a person would think about.

You are right - the old tank has to go.

[Danzer1]

Also, I question using an Oratex patch. Oratex is normally not painted, but getting an Oratex color to match your old paint will be nearly impossible.

Oratex does not need to be painted, but can be and it is painted all the time. Color matching is done just like any other color matching by any other manufacturer and/or paint system - a non issue!

[Geowitz]

Just a side note... I would guess they moved the filler opening so the wings could be folded without spilling fuel when the tanks were over half fuel. Problem with that though is you can't fill the tanks to full when they are in flying position.

[avidflyer]

I would not mix different kinds of fabric myself. I recovered a set of wings this summer from a Kitfox 4. It had one new tank and one old one. Nothing wrong with the old tank so I left it in. I did make a provision that would help if I ever had to change it out. Here is a picture of what I did. Basicly covered the wing except the area over the tank, then put a separate piece of fabric over the tank area. How does this relate to your question? I would cut the fabric long enough to wrap it around the rib and glue it in as best as I could. Then the new fabric would be glued down over the old fabric. I did rib stich these wings, and that would help to hold the joint together as well. In the last year, I recovered 5 wings, plus the rest of one airplane using the poly fiber system. JImChuk

[jrevens]

Bob,

I hesitate endorsing any particular product, but I do believe that Oratex would work very well for this. As far as color matching, the white Oratex is a very common white that matches the color of the powder coating that Kitfox has done, for instance, almost perfectly. As was said, it can certainly be painted, but then you might as well just use the same system as the original covering. It will have a different look from the rest of the fabric of course, but might look OK to you. FWIW, I would certainly consider removing & replacing just the fabric over the tank. Depending on how well the old tank is "glued" in, maybe the bottom fabric would have to be removed too? Others who have done this could lend a lot more educated expertise than I. I would cut the old fabric to leave extra over the tank on both sides, and then fold over & glue that to the ribs. Then I would cut the Oratex to overlap the 1" cap strips on both ribs, as well as extra to overlap around the trailing edge as well as the leading edge. If you had to do both top & bottom it would be good if you could use just one piece, starting at the trailing edge then curving around the leading edge and then around & overlapping at the trailing edge. The Oratex glue would be compatible with the painted surfaces of the original fabric - just scuffing & thorough cleaning is needed, to my knowledge. I suspect that you might possibly do the Oratex cheaper for this small job, considering the cost of the various chemicals/paints needed for PolyFiber.

That all being said, PolyFiber might be cheaper. Of course you will have to deal with masking and all of the painting steps to get to where you want to be.

My best advice would be that whatever you do, try to make sure it's something you can live with and be proud of, regardless of the potential time or expense involved. Consider the possible effect on the resale value of your airplane as well as your satisfaction every time you have to look at it.

[jiott]

John, you mentioned resale. That is one big reason in my mind to stick with the original fabric system. Any new owner may not be aware of a different type of fabric and its unique methods of application if it is in only one spot on the airplane.

Regarding matching whites, not as easy as it might appear. This summer I had to recover an elevator half. The original white paint on the other half was supposedly color matched by the paint supplier. He did fairly well, but it is not perfect-in bright sunlight you can tell a difference. Not really noticeable because the elevator halves are separated by the rudder, but if those two panels were butted together (like Bob is going to do) it would be much more noticeable. That's why I recommend making the patch seams on hard points like ribs, spars, trailing edge. These places get finishing tapes to break up the large flat surfaces.

[Bob Brocious]

Thank you, Jim and company. I appreciate your thoughtful replies. I'm enjoying the process of learning more about my Kitfox. I'll post more pictures shortly.