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Old 03-21-2018, 06:17 AM
Raybilt Raybilt is offline
Join Date: May 2012
Location: Florahome, FL.
Posts: 12
Default RV-7 tank skin first fit,..not so good.

Hello gents,
I'm working in the wing section of the builder manual, p. 7-5 FITTING THE TANK SKINS.... The 701 tank skin is not lining up as it should. Up to this point everything has fit perfectly and I've followed the builder manual religiously. I believe the problem may rest in the holes I've drilled in the W712 "z" brackets not being accurate enough which is causing misalignment of the baffle. I'm on my second set of brackets, still not satisfied and have another dozen coming from Van's, along with new nut plates.
All this buildup for an idea I'm contemplating and would like some input. When the next set of brackets arrive I plan on mounting them to the front of the spar without drilling the single 1/8" hole in their tops. I will cleco the tank skin to the baffle and then cleco the assy to the main spar. I believe I will see a better fit with the leading edge. If so I plan to then drill one hole in the most inboard bracket, using the baffle as a guide, and cleco it. I will then remove the leading edge so that a hole can be drilled in the most outboard bracket, again using the baffle as a guide, and cleco it to the bracket. The skin will then be removed, leaving the baffle attached with one cleco at each end and drill the remaining four brackets using the baffle as a guide.
With the accuracy of the prepunched holes I can see my drilling of the "z" brackets as the weak point. Any ideas, suggestions?

Thanks in advance.

Ray Piantanida
Florahome, FL.
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Old 03-21-2018, 06:30 AM
tgmillso tgmillso is offline
Join Date: Nov 2012
Location: Launceston, Tasmania, Australia
Posts: 643

I don't remember this part clearly however I do recall some drilling procedures that needed to be followed in addition to what the instructions called out. See link below.

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Old 03-21-2018, 09:23 AM
wirejock's Avatar
wirejock wirejock is online now
Join Date: Oct 2005
Location: Estes Park, CO
Posts: 3,076
Default Tank skin fit

Assuming the ribs are not causing the issue, the problem you describe is common and you're method to resolve it is correct.

Here's "the z-bracket method" I used.
First mark a center line on each z-bracket flange but only drill one hole in one flange of the z-brackets matching the hole size in the spar. You can fudge this center line a 64th to make sure the bolt head will clear if necessary. Center worked fine for mine.
I used scrap bolts and nuts next.
Secure the bracket using one bolt. Align center on the other two spar holes.
Another trick is three pieces of brass tubing from a hobby store. ID of the inner one is #40. OD of the outer is the spar hole size. The three pieces slide together to create a drill bushing. Now you can perfectly center drill the holes without messing up the spar holes.
Drill one more hole in the z-bracket. Insert a bolt. Drill the third. Remove and repeat for the others z-brackets.
Once all the z-brackets are done, install the plate nuts on the z-brackets and the plate nuts for the inboard spar z-bracket holes. Mark the other center line on the z-brackets. Install the z-brackets.
Cleko the tank together including the baffle. Use 100% clekos in the baffle to skin and skin to rib holes. Cleko the tank to the wing. 1/8" clekos fit the tank attach nut plates in the wing spar. Use 100%. Cinch it down with straps so the leading edge and tank attatch holes are perfectly lined up. Cleko them also. It should be exactly where it belongs now.
Check center lines in each z-bracket through the baffle holes in the next steps. They should be lined up perfect.
Drill the holes for the inboard baffle to z-bracket. Cleko them.
Remove the leading edge. You have to remove it leaving the tank attach because it won't slide out. You can remove it after.
The outboard end of the tank is now accessible.
Drill the outboard baffle to z-bracket holes. Cleko them.
Disassemble the tank skin from the baffle leaving the baffle clekoed to the two z-brackets.
Drill the remaining z-brackets inserting clekos as you drill.
Now you have a perfectly aligned baffle z-brackets.
It takes a bit longer but it's worth it.
Larry Larson
Estes Park, CO
wirejock at yahoo dot com
Donated 12/27/2018. Plus a little extra.
RV-7A #73391, N511RV reserved (2,000+ hours)
HS SB, empennage, tanks, wings, fuse, working finishing kit
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.

Last edited by wirejock : 03-21-2018 at 09:30 AM.
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Old 03-21-2018, 04:33 PM
Raybilt Raybilt is offline
Join Date: May 2012
Location: Florahome, FL.
Posts: 12
Default Thanks for the info....

Can't thank you enough, Larry. Good info and I'm anxious to get back on the project soon as my new Z brackets arrive.
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Old 03-21-2018, 09:10 PM
jcarne's Avatar
jcarne jcarne is offline
Join Date: Jul 2016
Location: Worland, Wyoming
Posts: 676

Yep I more or less followed the same procedure as Larry. If you haven't also read Mike Bullocks build log it is pretty much my standard for following as he detailed things very, very well.
Jereme Carne
RV-7A Emp. done
Wings mostly done
Fuselage almost done
Finish kit arrived
Exempt but gladly paying!
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Old 03-22-2018, 07:58 AM
RV74ME RV74ME is offline
Join Date: Dec 2015
Location: Auburn, AL
Posts: 119

+1 on what Jereme said above....MB documents this step very well on his website
Steve T.
N922WT (reserved)
KAUO (Auburn, AL)

RV-7 slow build
Fuselage kit COMPLETE
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Old 03-22-2018, 10:09 AM
Raybilt Raybilt is offline
Join Date: May 2012
Location: Florahome, FL.
Posts: 12
Default thanks for the info....

Thanks guys. Appreciate your info.
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