Van's Air Force
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Question about mounting the Fuel Tank
- Thread starter AltonD
- Start date
jferraro17
Opulence, I has it...
Most of the builders logs I've read talk about getting this as tight as possible. I strove for that, using the Checkoway method in hopes of acheiving that goal.
What kind of growth are you concerned about? Have you deburred the edges yet?
Joe
What kind of growth are you concerned about? Have you deburred the edges yet?
Joe
Alton,
I just went through the tank skin fitting process. I think the plans call for adjusting the baffle so the tank skin-to-leading edge skin fit is "perfect" (Vans' words). I wound up with an almost-zero clearance as you did, and I'm satisfied.
Hope this helps,
Dave
I just went through the tank skin fitting process. I think the plans call for adjusting the baffle so the tank skin-to-leading edge skin fit is "perfect" (Vans' words). I wound up with an almost-zero clearance as you did, and I'm satisfied.
Hope this helps,
Dave
What's more crucial is keeping the gap even along its full length. Zero, small, or large, keeping whatever it is constant is pleasing to the eye. This is particularly important when you start setting gaps between/against the fiberglass parts. The magnitude of the gap isn't really an issue, unless it's ridiculously large; keep it even.
John Siebold
-7, 190 hrs
-7, -450 hrs and counting
John Siebold
-7, 190 hrs
-7, -450 hrs and counting
AltonD
Well Known Member
Thanks for all of the replies. I was curious if I should have been concerned with heating and expansinon in the hot sun. But, , , If Vans' says a perfect, zero clearance fit, that's what it will be.
I did use the Checkoway method of fitting the baffle, and I did end up with a pretty good fit. Actually, I used the Vans' method first, replaced all of the Z brackets, then used the Dan's method. I was a little unhappy with the fit to start with. Turns out, I had to readjust the the spar support to remove the sag. After that, all was well.
I did use the Checkoway method of fitting the baffle, and I did end up with a pretty good fit. Actually, I used the Vans' method first, replaced all of the Z brackets, then used the Dan's method. I was a little unhappy with the fit to start with. Turns out, I had to readjust the the spar support to remove the sag. After that, all was well.
Fuel tank fit
I've just finished fitting the right wing tank (RV7) and have also noted that the tank skin to wing skin is actually less that 0 clearance in that the skins are almost starting to distort when the mounting screws are tighted. It's so close that a few passes with some emery paper on a sanding block will do it. I'm providing a tiny bit of clearance otherwise you may introduce cracks in the paint when the tank and wing skins expand at different rates or if you need to remove the tank. I too used the Vans method on the first wing and also ended up replacing all the Z-brackets. I don't know why they don't just update the plans with Checkoways method... it's much easier and accurate.
I've just finished fitting the right wing tank (RV7) and have also noted that the tank skin to wing skin is actually less that 0 clearance in that the skins are almost starting to distort when the mounting screws are tighted. It's so close that a few passes with some emery paper on a sanding block will do it. I'm providing a tiny bit of clearance otherwise you may introduce cracks in the paint when the tank and wing skins expand at different rates or if you need to remove the tank. I too used the Vans method on the first wing and also ended up replacing all the Z-brackets. I don't know why they don't just update the plans with Checkoways method... it's much easier and accurate.
Yes. I'd target ~10 thou. If it's 3-5 thou right now - leave it. Any less is asking for trouble, IMO. Remember - a piece of paper is about 3 thou thick.
The way I see it, a good-looking plane isn't the one with no gaps or clearances, it's the one with consistent and appropriate clearances. And I guarantee that anything you try to assemble with near zero clearance will bind or interfere upon final assembly. BTDT.
As for the growth thing, why would there me differential? Fuel? It's all aluminum so should all grow/contract the same. Even if there was relative growth, you sure don't want any sliding or movement.
The way I see it, a good-looking plane isn't the one with no gaps or clearances, it's the one with consistent and appropriate clearances. And I guarantee that anything you try to assemble with near zero clearance will bind or interfere upon final assembly. BTDT.
As for the growth thing, why would there me differential? Fuel? It's all aluminum so should all grow/contract the same. Even if there was relative growth, you sure don't want any sliding or movement.
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alpinelakespilot2000
Well Known Member
One painter I talked to said he liked to see a small gap. That way if the tank ever has to come off again (for whatever reason) the paint won't get messed up. FWIW, my gap was about 1/32-1/64 when clecoed and closed up to about 1/128 when riveted, but it is consistent all the way across.
Be sure to leave extra room where the the aft corner of the tank skins touch the leading edge skin. One or two of my corners don't sit perfectly flush becuase there is basically zero clearance. Short of taking the entire tank off the wing, though, there's really nothing I can do about it now. If it becomes a problem, I'll take the tank off before painting to file that corner down a tiny bit.
Hope this helps. Good luck.
Be sure to leave extra room where the the aft corner of the tank skins touch the leading edge skin. One or two of my corners don't sit perfectly flush becuase there is basically zero clearance. Short of taking the entire tank off the wing, though, there's really nothing I can do about it now. If it becomes a problem, I'll take the tank off before painting to file that corner down a tiny bit.
Hope this helps. Good luck.
There is at least one place in the plans where VAN's says to leave at least a .020 gap to allow for paint. (Can't remember where.)
I plan on removing the tank for painting. This makes for a much nicer look, at least in my opinion, and you will need at least some gap in order to get it on and off without damaging the paint.
I plan on removing the tank for painting. This makes for a much nicer look, at least in my opinion, and you will need at least some gap in order to get it on and off without damaging the paint.
Rick6a
Well Known Member
I would not interpret "perfect" as zero clearance. I seriously doubt Van or any other designer would have you strive for a zero clearance condition between abutting skins. In fact, it is standard sheet metal practice to allow for a consistent gap between two sheets. A specific gap is sometimes called out by the designer (+ or -) and on larger airplanes can even vary in width depending upon the design and its location on the airframe. If not specifically called out, a tried and true method that works well for the average homebuilder is be able to just barely insert a common index card between skins that butt each other.Thermos said:
AltonD
Well Known Member
Rick, from looking at your profile, I would say you know what you are talking about.
I am having a really good day. I just leak tested my first tank. I had a leak on the inspection cover and the BNC connector for the capacitance probes. The cover was expected, I haven't done the final sealing on it yet. I removed the cover and gooped proseal on the BNC, reinstalled the cover and all is well. It is a good feeling to have that behind me.
I am going to use the index card standard.
I am having a really good day. I just leak tested my first tank. I had a leak on the inspection cover and the BNC connector for the capacitance probes. The cover was expected, I haven't done the final sealing on it yet. I removed the cover and gooped proseal on the BNC, reinstalled the cover and all is well. It is a good feeling to have that behind me.
I am going to use the index card standard.
