Fabric cuts on the wing tank transition

[Birdseyeview]

I'm just starting to cover my series 6 wings and I am using Poly-Fiber medium fabric and the Stewarts System Ekobond adhesive. My Kitfox manual tells me to lay the wing down with the bottom side up and start by applying adhesive to the cap ribs and glue the fabric to them first, starting in the middle and working outboard to the ends. Then wrap the front edge of the fabric over the leading edge and up around the top of the leading edge spar. This leading edge area on the fabric should be cut in a "scalloped" pattern in between each rib as the peaks of each scallop wrap more fully around the front spar with the valley of each scallop matching the root of each rib. This is all pretty straightforward where the ribs are concerned but the manual doesn't describe what to do when I get to the wing tank. I'm assuming the scallop pattern should stop and a straight cut should begin and continue across the tank surface, probably at the same level as the bottom of the scalloped area. However, the manual is silent about how far up to go around the leading edge all across that area of the wing tank and whether the fabric cut edge should be straight or pinked. What distance up from the leading edge onto the wing tank have others gone and were your edges there straight or pinked? The first photo shows the scallop pattern from the manual but note that it doesn't show the transition at the wing tank and what to do there. The second photo below shows the transition area I'm attempting to describe in case my description above is unclear. Note that my manual is set up assuming using Poly-tac adhesive but I'm assuming that for my question about fabric trimming it shouldn't matter which adhesive I'm using. Appreciate any insight anyone may wish to contribute.

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[Delta Whisky]

Larry, your plans as described are what I did and I used the Stewart System as well. I'm pretty sure you can see what I did if you go to my log (see signature line). You'll have to scroll back a ways. I'm on the road now so I can't get to them.

[Birdseyeview]

Darrel, Thanks for your response and I'm impressed by your log entries. I figured out what to do to solve my issue and proceeded accordingly and it was successful. My first wing is covered and after the final shrink I'll move on to the other wing. BTW, did you shrink your fabric up to 350 or did you stop at 300?

[Birdseyeview]

My manual also tells me to install some drain holes on the bottom of the wing at the trailing edge near each cap strip rib. This is easy enough to do and Kitfox sells some very reasonable drain grommets, but are these really needed? What have others done and why or why not?

[PapuaPilot]

My manual also tells me to install some drain holes on the bottom of the wing at the trailing edge near each cap strip rib. This is easy enough to do and Kitfox sells some very reasonable drain grommets, but are these really needed? What have others done and why or why not?

Yes, they are needed. It is a standard practice for any fabric covered plane. You don't want water in the wings that can't drain as it leads to corrosion, mold and rot.

You want them at the lowest point of each rib bay, which is inboard at the trailing edge. The grommets reinforce the area around the holes you will make. I also put some on the stabilizers, rudder and elevator.

[mike92104]

Drain holes are needed, but I don't think the grommets are required.

[Delta Whisky]

I waited until the reinforcement tapes were installed and then used a solder iron to melt the drain holes thru at least 2 layers of material. I also used a scrap piece of aluminum with a hole the size I wanted as a location and size template. Grommets not needed.

[efwd]

I did not use grommets. The hole is necessary. I considered using the type of grommet that is applied to the exterior. They are somewhat of an airfoil shape that is closed at the front and open in the back. This design will cause a low pressure over the hole and, in flight, will draw water from the hole. I don't see water being a problem in my location and I don't aim to fly in rain. I wash my plane and I only have concern of water getting down into the tail wheel area. I cover every hole I can find with Duct Tape when I wash it. I cover the fuel cap vent holes as well.

[jrevens]

I agree that grommets are not needed. If you're doing floats, seaplane grommets might be a good idea as they shield and help draw any water out through the hole. I just did the soldering iron technique also. I have several soldering irons, but got one for a couple of bucks at Harbor Freight that has a nice sharp tapered point (about 3/16" diameter?). I've seen melted holes ( no grommets) on many aircraft, factory and homebuilt. If you have dihedral, locate the holes as close as possible to the lowest point in each rib bay. Don't forget the fuselage also.

[jiott]

I like the simple flat grommets, under the finish tape, because it gives a nice finished look to an otherwise afterthought looking hole.