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  #1  
Old 09-26-2022, 03:10 PM
Desert Rat Desert Rat is offline
 
Join Date: Aug 2018
Location: Wichita KS
Posts: 1,109
Default Fuel tank fwd support- one of life's little challenges :(

Well darn.

I bought a second hand almost completed wing kit to start my build journey. Fast forward a couple of years and I did the first temporary install of the wings on my fuselage.

Wings fit good, triangulated easily, incidence and sweep set, drilled/reamed the all important aft spar hole a few thousands undersize for a AN5 bolt. Life is good.

Today I started all the cleanup tasks you do after the wings are on, and very first thing when I started looking at locating the hole for the bolt that goes through the fwd tank attach bracket to the slotted steel flange coming off the fuselage, I realized that the guys I bought the wings from had helpfully pilot drilled a #30 hole in exactly the wrong spot on the starboard tank.

I can't center the bolt hole on this because it's way to far out of the slot for the bolt to give any meaningful support to the nose of the tank, and I can't use it for as a rivet hole for one leg of the nut plate because it's a #30 hole instead of a #40.

This last part is what really sucks because one leg of a k1000-428 nutplate lines up perfectly with it.

As I see it, my options are:

1- to upsize one leg of a nutplate for a #30 rivet, which is iffy because the call out is for a skinny nutplate, so that would put the big hole and little hole uncomfortably close together.

2- to clock the nutplate vertically instead of horizontally and fill the errant hole with a double flush rivet.

3- to pull the tank off, drill out the aluminum angle from the inner end and build a new one without the offending hole, with the pro seal mess and extra time involved.

4- vans suggestion (which they just came back with while I was typing this) fabricate a new bracket and extend the ears out from the fuselage a little bit more.

curious what opinions the collective might have...
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Terry Shortt
AGI, CFI, CFII, MEI, A&P, Janitor
RV7 Empennage & Wing done
Fuselage almost done
Avionics almost done
90% done, 90% to go
#72651
https://eaabuilderslog.org/?blprojec...t=all&listcat=
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  #2  
Old 09-26-2022, 03:17 PM
Laird's Avatar
Laird Laird is offline
 
Join Date: Feb 2007
Location: SoCal
Posts: 219
Default

I'll take "what's behind door #4", Bob!

Quote:
Originally Posted by Desert Rat View Post
Well darn.

snip

4- vans suggestion (which they just came back with while I was typing this) fabricate a new bracket and extend the ears out from the fuselage a little bit more.

curious what opinions the collective might have...
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  #3  
Old 09-26-2022, 04:27 PM
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sahrens sahrens is offline
 
Join Date: Jan 2007
Location: Battle Ground WA
Posts: 626
Default #4

Clearly the best solution.
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  #4  
Old 09-26-2022, 05:55 PM
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PaulvS PaulvS is offline
 
Join Date: Aug 2019
Location: Western Australia
Posts: 1,326
Default

#2 or #4 depending on whether you can get angle stock that is wide enough.
If doing #2 I think you can fill the hole with a normally set universal or countersunk rivet. It doesn't need to be double flush because there is no interference.
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Paul vS (yes I'm also a Van)
Building RV-6A #22320 O-320 FP. Wings and tail complete, fuselage almost done, working on canopy.
Flying my Aeroprakt A-22 STOL and the aero club's RV-9A while I build
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  #5  
Old 09-26-2022, 06:05 PM
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wirejock wirejock is offline
 
Join Date: Oct 2005
Location: Estes Park, CO
Posts: 5,879
Default Attach bracket

Door #4.
Easy peasy.
Go to a metal supply and buy a piece of the same thickness and same alloy. Ask them to bend it where you need. They might charge a few bucks but it's worth it. They have the tools.
All you have to do is drill and cut.
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Estes Park, CO
E-mail: wirejock at yahoo dot com
Builder Blog: http://wirejockrv7a.blogspot.com
Donated 12/2022, plus a little extra.
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Disclaimer
I cannot be, nor will I be, held responsible if you try to do the same things I do and it does not work and/or causes you loss, injury, or even death in the process.
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  #6  
Old 09-26-2022, 06:16 PM
Desert Rat Desert Rat is offline
 
Join Date: Aug 2018
Location: Wichita KS
Posts: 1,109
Default

Just to clarify, if we're talking about extending the ears, it's not angle stock. It's a bent piece of 4130 steel.

I guess my reservation about that solution is that the bolt imparts a vertical load on what's essentially a pivot point because that bolt doesn't get torqued down to create a lot of clamping force. If you make the fuselage bracket longer, even by a little bit, it's creating more of a bending moment into the fuselage structure. I realize it's not much, but it's something.

I don't know what sort of loads are carried up there, but it seems like it has to be significant, because the structure and hardware is pretty beefy.
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Terry Shortt
AGI, CFI, CFII, MEI, A&P, Janitor
RV7 Empennage & Wing done
Fuselage almost done
Avionics almost done
90% done, 90% to go
#72651
https://eaabuilderslog.org/?blprojec...t=all&listcat=
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  #7  
Old 09-26-2022, 06:23 PM
PaulvS's Avatar
PaulvS PaulvS is offline
 
Join Date: Aug 2019
Location: Western Australia
Posts: 1,326
Default

Ah OK! I assumed it was made from angle stock, same as the RV-6. I've recently cut those parts from 2.5" x 2" x 3/16" aluminum angle.

Honestly I don't see why #2 would not work just fine.
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Paul vS (yes I'm also a Van)
Building RV-6A #22320 O-320 FP. Wings and tail complete, fuselage almost done, working on canopy.
Flying my Aeroprakt A-22 STOL and the aero club's RV-9A while I build
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  #8  
Old 09-27-2022, 10:47 AM
CATPart CATPart is online now
 
Join Date: Jan 2012
Location: up up and away
Posts: 400
Default

Quote:
Originally Posted by Desert Rat View Post
If you make the fuselage bracket longer, even by a little bit, it's creating more of a bending moment into the fuselage structure. I realize it's not much, but it's something.
To answer this concern, some images of the structural arrangement here would be helpful. Would be good to see both the mounting bracket and its backup structure. Actual pics or snippets of the drawing. I doubt it is a problem, but lets see to be sure.
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