Model IV wing tank repair DIY.

[4Hummer]

Here is the Tank sealer. (sitting on the cut out of one of the tanks.. )


Aircraft Spruce Part Number: 09-03477
https://www.aircraftspruce.ca/.../gastanksealer.php...
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Close up of the Ribs, I ended up leaving a fair amount of the old epoxy that was glued to the baffles, as it helps line everything up. (Removed all loose crap first)

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First Coat Lids
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Tank Bare.
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Tank 1st coat:
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2nd Coat; FYI it takes 2 Quarts to seal both tanks.
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[4Hummer]

Sanded off 1/2" of the Gel Coat all the way around the top of the tank, and the lid, This is to prep for sealing the lid back to the tank. A 1" Fibreglass tape will be glued to the top once the lid is glued down internally

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The Lid
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I mixed the epoxy with Micro Ballon's into a couple different consistency. 1st Coat Very thin to brush along the edges, 2nd a bit thicker to fill some of the voids. and 3rd extremely thick to re-glue the baffles to the lid.

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One Lid Glued down. Will need to wait a couple days before doing the other as I have run out of things to place on top to get that perfect seal.

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I'm pretty impressed with myself. One lid back on. (Weights removed)
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seams came out real nice too. This is after a bit of sanding
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Added a 1" top layer of tape over the seam. (might be overkill.... but...)
Tomorrow I hope to glue the lid on the other wing. Just need a hand moving it off the rotisserie, and putting this wing into it.

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[bbs428]

Very interesting thread. That is some serious work. Unbelievable the chunks that were in the tanks. Sure is looking good now!

All the best getting it all done.

[Shadowrider]

Crazy what was in your tanks. So is the yellow chunks resign from the tanks?

[4Hummer]

Yes it is.

[4Hummer]

One Wing repaired and ready to be recovered.

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I notice the section of the tank I cut out was covered in what looked like plastic wrap, After double checking the build manual, I discovered that the tanks are indeed supposed to be covered in some sort of plastic to prevent the fabric from sticking to the tank.

Here the Paint has been stripped for the fabric repair, MEK makes quick work of this, The Poly-Tone, Poly-Spray and Poly-Brush just wipe away with a bit of rubbing, Notice the Mask.... these products will turn you into Rainman. Wear a proper mask in a well ventilated area, or you'll be counting socks tumbling in the dryer and drooling into your soup!

(Top of tank has also been recovered in packing tape)
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Fabric patched in. still need to iron out the seams.
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Calling it quits for today. Tomorrow I hope to get the first couple coats of Poly-Brush on, followed by the tapes.

[Eric Page]

I notice the section of the tank I cut out was covered in what looked like plastic wrap, After double checking the build manual, I discovered that the tanks are indeed supposed to be covered in some sort of plastic to prevent the fabric from sticking to the tank.

Hmmm, that's interesting. When I stripped my wings recently, the fabric was glued right to the tanks by the Poly-Brush and had to be peeled away with considerable force. I'm now in the process of sanding down the Poly-Brush to eliminate roughness under the new covering. I'll have to pay particular attention to tank prep before I re-cover. Thanks for the tip!

[jrevens]

Re: gluing fabric to surface of the tanks... I'll throw this out - If your tanks have a perfectly smooth surface and are made & mounted such that the surface height matches that of the wing ribs, then gluing the fabric to it should be fine (probably done as Jerrytex described). If not smooth, and especially if the surfaces don't match the upper & lower elevations of the ribs, adding false ribs to the tank surfaces would seem to be the way to go, gluing the fabric to the false ribs & shrinking it the same as you do between ordinary ribs. That's what I had to do on my 7SS. Many of us mount the false ribs on small standoffs, matching the contour of the ribs & allowing the fabric to be laced to them with the proper technique, although I don't think that's absolutely necessary. I know of Mod. IV builders who laid down a layer of felt-like material over the tanks to insure that the fabric didn't stick to it or rub on it, and to insure a smooth surface. I also know that some (most?) do not even attempt to lace the fabric to those false ribs, and some even glue on "fake lacing" to maintain a uniform look.

[4Hummer]

In regards to spraying the Poly-Fibre system, Seems everyone says "It's the easiest paint system to spray" followed by "you need a $1500 + professional spray system setup to get a good paint job"

I have a small air compressor, which I don't think would cut it, add to that I'd need larger hoses, a water separator, filters, regulator and a HVLP paint gun, this all adds up. another option was the Turbine HVLP system buts that over 2grand Canadian. Seems like a lot of money to spend for a small fabric patch.

I took a chance and went a totally different route. (Warning this may offend the Nay Sayers)

AMAZON Neu Master HVLP paint sprayer. $108 Canadian.

https://www.amazon.ca/NEU-MASTER-N31...xpY2s9dHJ1ZQ==


This is a 600 WATT electric paint sprayer, super easy to clean, comes with 3 different nozzle sizes, has 3 spray patterns, and adjustable flow control

I built myself a test frame and covered it in fabric, After testing the different nozzles I determined the smallest nozzle (RED) sprayed best, and was actually very impressed with the results once dialled in

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I didn't take many pictures of the process, but I can ensure you this sprayer laid down the Poly-Brush, the Poly-Spray, and Poly-Tone extremely well.
plus its super easy to Clean,

Heres a picture just after applying the first coat of Poly-Tone
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Only thing I would do different, is recover the entire section of the wing, instead of just putting in a "patch", I have a few winkles under the tapes where to two fabrics where glued together, Overall however I'm extremely happy with the results,

[4Hummer]

Wings back on tomorrow hopefully.




I bled the poly-tone to the edges of the wing and over to a tape line along a rib, (instead of just the patch cut out) And painted in the stripes.


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