Last weekend I was able to complete the riveting of the left tank ribs in one session.
The right tank I had completed the weekend before and used the "set it and forget it" method described on VAF where you let the sealer set up overnight and then come back in the next day or two and rivet.
Both approaches have their positive and negative sides.
Partial cure:
+ Less Mess
+Easier to see the shop end of the rivet to judge how well you riveted
- Need to remove the partial cured sealant from each hole when you put a rivet in
- Need to add new wet sealant to each hole
Wet Seal:
+Wet sealant already there when you go to rivet
+ More sealant seems to squeeze out (ie. Tighter seal potentially)
+ If you have the time riveting really doesn't take that long once you get the rhythm down so avoids waiting overnight or longer
- A mess for sure
- Rush against time while the sealant sets up
If I were to have it to do all over again, I think I really would just set aside the time and rivet wet. Either way there is a mess involved.
I am finding the tanks so far to be more enjoyable than I thought they would be, mostly because I see them progressing quickly. Rather than dragging the tanks out for months on end, once I put the sealant on there I have to finish so it forces me to set aside an entire day to do the work.
I think the stress for me on the tanks is keeping things as neat as I can, but I am using the philosophy here that more seal means less leaks. We will see when the time comes.
I used the individual tubes of proseal and am finding that it is costing around double what it would have if I had just purchased two quarts and some vet syringes as others have. While someone on VAF did illustrate a method which in theory would use seven tubes for the whole project, I found that I am going to take more like ten. They do save you from the messy mixing and with the caulking gun from Vans it works well as long as you release the pressure from it by hitting the tab on the back of it after you are done. That way the dribbling stops while you work on the piece you just coated.
Another tip is to cut scrap strips of aluminum to use as your spreader. Around 5/8" x 4" in works well. Much easier to spread the bead with that than a brush or anything else.
For the swirl on top of the shop head, so far a toothpick works best for me.
Next up: J Channel, followed by the fuel floats and end rib. Then final check, and the dreaded baffles :) I most likely will do a leak test prior to putting the baffles on.
Monday, May 18, 2015
Sunday, May 3, 2015
Fuel Tank Sealing
Up until now, I have been approaching the fuel tanks in small bites, hoping that they would just magically construct themselves.
I am happy to announce: I officially jumped into the pool this weekend. I had decided to use the individual proseal canisters (3.5 OZ available at Aircraft Spruce). Tom Martin on the VAF divided the job up nicely into seven sessions. That was great for me, because it clearly identified the work, and defined the milestones.
The problem is: You need to work fast once you mix the canister. It gives you around two hours of time before the proseal starts to get more difficult to work with. I ended session#1 with only the stiffeners done on the left tank, and the fittings done on the end ribs. Some of the rivets are not the best on the fittings and I am debating drilling them out but for now they will stay the way they are. So it looks like this will be eight sessions at the minimum.
But I am getting ahead of myself here.
The fuel tank sealant in my opinion is as bad as everyone says, and in a sense easier. It gets everywhere you don't want it to get. That is not because it flows, but because it sticks to your glove, or your person, and then transfers on to another surface. I also made the rookie mistake of putting too much on, so when I put the parts together it squeezes out and gets everywhere.
I chose not to use the partial cure method that I see on the forums. I think that wet riveting will bring the parts together while the seal is still wet and get the parts as close as possible. I can see that this will be a mess once I start the ribs.
While it is a messy situation, one relief is that once you put the sealant on, it does not drip or move anywhere. It is the consistency of molasses, maybe even thicker.
More updates as I work through the tanks. The replacement parts for the aileron arrived as well. I am going to build a third one as the removal of the rivets in the trailing edge did not go well.
I am happy to announce: I officially jumped into the pool this weekend. I had decided to use the individual proseal canisters (3.5 OZ available at Aircraft Spruce). Tom Martin on the VAF divided the job up nicely into seven sessions. That was great for me, because it clearly identified the work, and defined the milestones.
The problem is: You need to work fast once you mix the canister. It gives you around two hours of time before the proseal starts to get more difficult to work with. I ended session#1 with only the stiffeners done on the left tank, and the fittings done on the end ribs. Some of the rivets are not the best on the fittings and I am debating drilling them out but for now they will stay the way they are. So it looks like this will be eight sessions at the minimum.
But I am getting ahead of myself here.
The fuel tank sealant in my opinion is as bad as everyone says, and in a sense easier. It gets everywhere you don't want it to get. That is not because it flows, but because it sticks to your glove, or your person, and then transfers on to another surface. I also made the rookie mistake of putting too much on, so when I put the parts together it squeezes out and gets everywhere.
I chose not to use the partial cure method that I see on the forums. I think that wet riveting will bring the parts together while the seal is still wet and get the parts as close as possible. I can see that this will be a mess once I start the ribs.
While it is a messy situation, one relief is that once you put the sealant on, it does not drip or move anywhere. It is the consistency of molasses, maybe even thicker.
More updates as I work through the tanks. The replacement parts for the aileron arrived as well. I am going to build a third one as the removal of the rivets in the trailing edge did not go well.
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