Sealing My Fuel Tank - Part 2

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Finally finished sealing up my fuel tank by gluing on the top. I did this with out the help of a friend. I had no problems or issues with this. I am quite pleased with the outcome. Before putting on the top I plugged the drains and filled it with water and observed no leaks!

Since the tank was basically finished, I did work on attaching the bottom skin of the fuselage on Sunday. I'm making progress but it is slow going for me.

Sealing My Fuel Tank - Part 1

Yes Paul, I have been working on my project...

My friend Larry Geiger came over yesterday to help me seal my tank with ProSeal. Larry had completed an RV12 not too long ago and he had some experience with ProSeal on his RV12 fuel tank. Over the last several weeks I worked on preparing the tank for sealing. I cut both holes for the filler cap and the fuel sender. Attached the corresponding nut plates and prepared the fuel sender for final installation.

I made a few changes to how the top attaches also. While using the EAA chapter metal break to bend the end flanges on my tank top, I decided it might be easier to mount 1/16"x3/4" aluminum angles to the inside side walls at the top and use them as a mounting surface for the tank top. I think it turned out well. Bending the flanges to the sides of the top would have been possible (just like I did for the bottom), but not nearly as easy to construct.

I purchased solid pull rivets from Hanson Rivet & Supply Co. (800-777-4838). I needed 3 different grip sizes to complete the project. These rivets are on the pricey side, so be warned. You don't have to use this style of rivets, but they don't have to have their centers sealed like regular rivets do.

Here are several photos of the tank after part one of the sealing. I don't think I'll have to add sealant to anything I have done, but I will do a leak test with water before I put on the tank top (Part 2).

I found that working with ProSeal wasn't tough, but I was glad to have some experienced hands around to help. Larry applied ProSeal to the stem of each rivet before placing it in its' hole. I placed a bead of sealant on each surface and then flattened it out with a popsicle stick. Towards the end of the project, the ProSeal was not as pliable as it was when we first mixed the batch, but it was still manageable. I used acetone as a solvent and was able to clean up spots yet a day later with no problem. Just make sure the room is ventilated when using this stuff. After the ProSeal is squeezed out of the seems, just use a popsicle stick(s) to smooth out and scrape off the excess sealant.

I have added many photos to my project album, so don't forget to take a look at it if you want to see more than what I posted here. Just click on the slide show in the right hand column of this page to be linked to the album.

Continued to construct fuel tank

The last couple of weekends has been spent on constructing my fuel tank.

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I spent some time locating where I wanted my fittings and what size I wanted. I am putting in an extra fitting in the top rear so I can plum in a auxilary fuel tank later. I figured now was the time to do this regardless if I ever do it. In the photo above, I found a way to center the hole in the tank side with the weld puck so I could drill the rivet holes.

I am going with a 3/8" fuel line because it will be plenty big enough and requires fewer fittings. I bought this shut off valve from Great Plains A/C Supply. It fits into the finger strainer which fits into the weld puck.

I carefully bent one flange at a time and then test fit before bending the next flange. I could only use my 18" mental brake on the 1st end flange. From that point on I had to clamp the piece to my work bench using a 2x4 cut to size and hammer the peice to form the flange .

Here is where I'm at today. There are some gaps, but experienced builders tell me that the Pro-Seal will fix all this. I'll let you know...

I will begin to form the lid this coming weekend.

Finally back to work - Fixing mistakes on my belly skin.

I am finally back to having time to work on my project! Please take notes from this entry so you do not make the mistakes I made on my belly skin installation!

My 1st mistake was not cutting my belly skin with the extension at the forward edge that overlaps onto the bottom of the center section. I simply forgot to review the plans carefully and when I laid out my bottom skin, I just forgot to include it. The plan was to put a splice that would overlap both the center section and the belly skin and rivet it into place. But then came my 2nd mistake which has caused me to re cut the forward section, so now I have included this extension.

So I cut my belly skin out in one long piece as shown on the cookie cutter sheet (sheet #7) in the plans. Reading the posts on the Yahoo Groups email list about how best to install the belly skin, most people agree that it is too difficult to install a single piece of skin. Most builders agree that 3 pieces is the way to go. I chose to cut my skin into lengths that would span between F6 and F8, F8 to F9 and then F9 to F12. But wait a minute!!! It's not that simple.

I measured the distance at the center line from the bottom of F8 to the bottom of F9 and cut my forward skin piece using this measurement. This was my mistake. This piece needs to be about 1.5" longer than this measurement because of the geometry involved at the F9 bulkhead. As you can see in the photo below, my 1st attempt was not long enough so that when I rolled the skin around the bottom of F9, my bottom skin edge did not mate up with the F9 bulkhead flange.

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After a conversation with Dave Thatcher and a trial fit of the other two pieces, I came to the conclusion that I just needed to re cut the forward section bottom skin.

One other thing that I would like to mention is that the forward edge of this forward section of the bottom skin will need some trimming to fit around the F6 bulkhead as well. I can't find where the Instruction Manual or the plans tell you this. Again this is because of the geometry of the F6 bulkhead which leans rearward at the top. You must trim the outer forward edge so as to fit nicely around the flange of the F6 bulkhead. This trimming also eliminates any interferance from the rear spar of the center section gives you when you try to roll the skin up around the F6 bulkhead flange. I found that the trimming starts where the F6 bulkhead flange begins to curve upward. Take your time trimming, so as not to remove too much material. I used some poster paper to get to shape and transferred this shape to the metal before I began cutting. Below is a photo of both the before and after forward skin pieces.

The re cut piece is on the right and is 2" longer, has the forward overlap extension and does not yet have the side flanges bent. I'll get the flanges bent this week and attempt to install the bottom skins again next weekend.

Bending up the fuel tank "box"

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I haven't done much lately but I did bend up my fuel tank "box" today. I used an 18" table top metal break that I bought at Harbor Freight a while back. This took ten minutes to complete. I bent the 1st two sides and then turned the piece around. I then bent the "joint" flange and then the final side. Again, I do not have any flanges for the top and bottom attach points because I decided to put them on the top and bottom pieces themselves.

Fuel Tank Construction Begins

I haven't worked a lot on my project lately as I have been managing my son's Little League baseball team, but I found some time this past weekend to start on the fuel tank. Actually, I have been in the planning stages for a while now. In one of my conversations with Dave Thatcher about how to proceed with the fuel tank construction, he mentioned that he had drawn up a new design for the tank which eliminates the mounting angles that are attached directly to the tank and instead incorporates straps from which the tank hangs from. This sounded good to me, so I had Dave send me the yet to be published drawings. In these drawings was a new 10.5 gallon tank design which works well with the floor mounted rudder pedals, but not the hanging pedals. So, I'm sticking with the demensions of the original 10.5 gallon tank, but I will be using the straps to hold it in place.

Here is a photo of what I have cut out so far. I used an air cut off disk to trim close to my lines and then filed up to them. I'll be cutting out the top and bottom pieces next. Another thing I am doing different from the plans is putting all the flanges on the top and bottom pieces instead of this piece (which I call "the box"). I discussed this with Dave as well and he seemed to think this was a good idea.

Finished work on rudder pedals and brakes

Painted and mounted the master brake cylinders on the rudder pedals.

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