CHAPTER 20 - Closing the Tank
With everything else done, it was time to close the tank. Everything was thoroughly cleaned out of the tank after scrubbing the adhesion areas with a wire brush, then cleaned with Naptha. Proseal was mixed and spread, and the back baffle laid in place. Let the races begin!
Since Judi had been so helpful with cleaning tools and such, I offered her the rivet squeezing job. I placed clecoes in every other hole and then quickly did the rib attachments with pop rivets. Next, I placed solid rivets in their holes while Judi followed behind me with the squeezer. She got a break while I removed the rest of the clecoes, then we finished the remaining rivets.
Once the riveting was done, we attacked the excess proseal with Naptha, and also added Proseal over rivets on the back of the tank. A little extra Proseal in the back corners, and it was done. To keep the rear flanges together while the Proseal set, I clecoed the tank back onto the wing spar. I laid saran wrap over the spar to keep the tank from sticking to it, which worked just fine. I will continue with adding the screws and nutplates after the leading edge is riveted and back in place..
In the last photo you can see my setup for doing the 'balloon' test. A balloon is attached to the outlet with a bit of fuel lube and many wraps of rubber band. The sender and access plate are in place with fuel lube and the sump drain is also attached. As extra sealant for the fuel cap, the opening was covered with packing tape. An aluminum tube was bent in a 'U' and flanged to fit the vent fitting, then attached. The pump is a hand-pump commonly used for beer kegs; its hose is attached to the aluminum tube with a tube clamp. The tank was filled until the balloon was inflated as shown, then left for 24 hours. Sadly, my first tank had a pinhole in the inboard rib joint which took some effort in our bathtub with soapy water to find. Once found, a liberal application of proseal over the naptha-cleaned area took care of the problem and the balloon remained standing. The second tank held on the first try.
By the way, in the first photo you can see the wing in place in the jig behind Judi. I tell visitors it is a sculpture I am doing, called 'Dreams of Flight'. Strangely, this gets less reaction than when I tell them what it really is.