Made great progress on tanks

Jared cam over and helped with tanks today. I’m very grateful to have a friend that has done this before and is so generous with his time. I would never have made as much progress on my own. Learned a ton today.

Everything we did today involved fuel tank sealant.  We used FlameMaster Chem Seal that I bought from Van’s. This stuff was invented by satan to torture builders. It smells like ass. It is incredibly sticky and gets on everything. Every part, every tool, every cleco, your hands, you arms, the work bench, the floor, EVERYTHING! I went through an entire box of nitrile gloves today. It is a two-part concoction that you mix ten to one by weight.

We sealed and riveted the flanges to the rear inboard ribs. Then we riveted the drain flange to the skins (after undimpling the holes that I accidentally dimpled in the skins). We riveted the fuel filler flanges to the skins. We riveted the stiffeners to the skins. We set up the left skin in the cradles, applied the sealant to the skins and then riveted the ribs in place.

 

 

 

Today’s Time (hours): 9.0
Wing Time (hours): 202.0
Total Time (hours): 354.0

 

Riveted rear spars to ribs

Riveted the rear spars to the wing ribs. I tried to use the squeezer but it was cumbersome with several different rivet sizes and with the flanges in the way. So I switched to the gun. This was much easier.

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And of course, no section is complete without a few mistakes. I used the wrong size rivets in ribs behind the doublers. I used 4-4’s and needed 4-5’s the shop heads were too thin to be acceptable. So I drilled them all out. Nine rivets in total. I couldn’t punch the rivets out because there was nothing to back them up when I hit them with the punch. So I had to drill them all the way out. I was super careful but the holes are enlarged ever so slightly. If this wasn’t a critical structure, I’d probably just re-rivet it but this area carries the load from the ailerons and flaps. So I’ll go with a larger river to ensure structural soundness. I order some -5 rivets, a #21 drill, and a 5/32″ rivet set from Spruce.

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I also put in an order with Van’s for some fuel tank sealant.

 

Today’s Time (hours): 2.0
Wing Time (hours): 69.0
Total Time (hours): 280.0

Did the Nasty

Decided to just get this out of the way tonight…

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I went through three changes of gloves and still managed to get it on my hands.

Prepped the scuffed surfaces with isopropyl.

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Sealed the trialing edge ribs in place. Peeled the tape and stuck the top skins to the trailing edges. Weighted down the aft section to ensure good bond of the skins to the ribs. The sealer cures in six hours according to the data sheet. So should be riveting the trailing edge and finishing up tomorrow.

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Bent the trim tab hinge pin per the plans.

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Today’s Time (hours): 1.0
Empennage Time (hours): 119.5
Total Time (hours): 119.5

 

Assembled Trim Tab

Bought a 3/4″ MDF panel at Home Depot. Leveled it out on the bench and shimmed the dead spaces with sheets of paper to create a flat surface.

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Prepped the skins, spar, and trailing edge with isopropyl.  Mixed up a small batch of fuel tank sealant and put a thin layer on each side of the trim tab ribs and set them in place. I used the 3M VHB tape on both sides of the trailing edge. Used clecos to align it with the bottom skin and set it in place. Then I clecoed the top skin in place along the spar and trailing edge. I peeled the paper from the VHB tape between the top of the trailing edge and the top skin removing clecos as I went to avoid tearing the paper. I replace the clecos to clamp the whole sandwich together while the tape sets up.

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The sealant is ridiculously sticky and smells like ass.

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I riveted the top skin and hinge to the spar.

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All done!

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Weighted down the skin with a board and some 2×4’s to ensure contact between the skins and the ribs until the sealant sets up. The spec sheet says there is a 6 hour cure time for the B 1/2 sealant I used.

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Today’s Time (hours): 1.5
Empennage Time (hours): 101.5
Total Time (hours): 101.5