Tanks not sitting right

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EchoWhiskey
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Joined: Tue Sep 18, 2018 9:15 pm

Tanks not sitting right

Post by EchoWhiskey »

After wrestling for hours with first tank, i am now working on the other and i have a fitment issues, in attempting to flush top of tank with top of ribs, i cant do it without bending the tank. Which i dont think is right. The two pics are diagonally opposite. When i flush one corner, the other pops up, and vice versa. This is with tank located such that i can mount the support brackets in their proper location. I had a similar issue with the other wing but lest drastic so i was able to make it work. Not so sure on this one......any thoughts or insight greatly appreciated.
Ed
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Ed Whitaker
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What do you get when things don't go as planned? Experience.
EchoWhiskey
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Joined: Tue Sep 18, 2018 9:15 pm

Re: Tanks not sitting right

Post by EchoWhiskey »

After hours of scrutiny, i have concluded the tanks are warped.
Ed Whitaker
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What do you get when things don't go as planned? Experience.
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BDA
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Location: Kenai Alaska

Re: Tanks not sitting right

Post by BDA »

Can you bend the mount tabs?
SuperStol XL Alaskan With Titan 340
N331AK. Shawn Taplin
Wing extensions,Symetrical Airfoil tail ribs (NACA 21)
Mods in progress: Heavier struts, Double slotted flaps
Goal: 15mph no wind
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SheepdogRD
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Location: West of Atlanta, GA

Re: Tanks not sitting right

Post by SheepdogRD »

The tanks may be slightly misshapen because they're sheet aluminum, and they tend to warp a bit when welded.

The tanks just need to fit in the space. You want to find the right position before drilling any holes. After making sure they fit, then you can set the spar bracket positions.

For my installation, I made sure the tanks fit in the space, and I supported them in that position. (Note: There's not much of rib #2, since it's at the middle of the tank, but its bottom capstrip still runs under the tank, so it should be under there when getting the tank in position.)

Once I saw that the tank fit properly, and I made sure that I could get it back out, then I fit the spar brackets to the tank brackets, marked their positions, and installed them on the spars.
Richard Holtz
Highlander N570L -- Ms. Tonka -- in gestation

If just enough is really good, then too much ought to be perfect.
EchoWhiskey
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Posts: 63
Joined: Tue Sep 18, 2018 9:15 pm

Re: Tanks not sitting right

Post by EchoWhiskey »

Apparently the most recent build manual has a new section for alum tanks. No cap-strip on bottom, just has to fit cavity. That makes this MUCH easier.
Ed Whitaker
Humble Novice

What do you get when things don't go as planned? Experience.
EchoWhiskey
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Posts: 63
Joined: Tue Sep 18, 2018 9:15 pm

Re: Tanks not sitting right

Post by EchoWhiskey »

Following up on this question, this misalignment was while mounting tabs. I was under the impression the tank needs to be flush to tops of both ribs. Which makes a lit of sense but i am told by factory is not important. With that allowance, the tanks fit. However I still have an issue with 3 or 4 ribs leaning enough to notice. I have searched the forum for other instances of rib lean and found nothing. I am interested to know if anyone else has experienced this.
Ed Whitaker
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What do you get when things don't go as planned? Experience.
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SheepdogRD
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Re: Tanks not sitting right

Post by SheepdogRD »

When I was fitting my aluminum tanks, I finally realized that there is twist in the wings, but no twist in the tanks. It's a matter of getting them so nothing protrudes before attaching the brackets to the spars.
Richard Holtz
Highlander N570L -- Ms. Tonka -- in gestation

If just enough is really good, then too much ought to be perfect.
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