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Tank Baffle

R

rulmen

Active Member
Forum;

I bought a partially completed kit. The right wing is done, I am working on the left. I am having trouble leveling the tank baffle. I have tried all kinds of shims but I can never get it to the exact place where the tank skin rivets wont hit the baffle at the bend. To compound the problem, the previous builder already installed the nutplates in the spar web. The plans are horrendous!!

I have a prepunched skin for the tank.

Question: How do I line up the holes in the skin with the right place on the tank baffle? I can never seem to find the right height. What size shims did everyone use to hold the take baffle off the spar?
 
I can't remember the exact thickness of my spacers, but they were just strips of wood I ripped on the table saw. My rivets are pretty close to the baffle radius whick is why the plans call for countersinking rather than dimpling these rivets.
 
If the ribs are in place you have to pull down pretty tightly with straps to get ribs into the leading edge and have the baffle in the correct place place.

Mark a rivet line very carefully on the baffle, there is little tolerance for error here.
 
The rivet line is just BARELY aft of the baffle enough to use dimple dies (mine left a VERY SLIGHT impression on the radius where the baffle 'web' meets the baffle 'flange'... Most countersunk these rivits as previously mentioned; since I *could* do the dimpling, I did...

Hope that helps... I think the previous comment about using pressure to force the ribs foward in the skin is an important point to make sure you have as much room as possible, even if you choose to C/sink.

Chris
 
Thanks Chris. I have assembled and disassembled it a million times sweating that clearance. I am also vexed about the spacers under the baffle, it is a real bear.

Thanks!

Rich
 
My spacers were 15/16 (.937)..

My holes were tight, like Chris's. Some dimpling was tight enough to leave a very slight scratch on the web of the baffle which had to be buffed out. Very close, but able to be squeezed ok when setting those rivets. You might have to grind a little off the end of the hand squeezer frame to keep from scratching the baffle web, depending on the type of squeezer you have. Watch that your shims are not sitting on the factory head of the 470 rivets in the main spar. If I had it to do over, I would still dimple both the skin and the baffle. See below from my kitlog site.

FP16052010A0000J.jpg
 
I definitely agree that the plans leave a bit to be desired here. I did a LOT of careful measuring, math, and trial fittinig and determined that 15/16" spacers are what was needed between the baffle and spar doubler webs. There is NO wiggle room for the row of holes in the spar doulbler, with its 1/2" flange. I used a couple of 3/16" steel rods spanwise, overlaid perpendicularly with several pieces of 3/4" square tubing from the hardware store. It makes for a very stable platform for the baffle. I seem to remember inspiration for the idea from Vince Frazier's Rocket website. Lots of good ideas there, including pop riveting the baffle in place before fitting and drilling the skin.;)
 
longranger said:
I definitely agree that the plans leave a bit to be desired here. I did a LOT of careful measuring, math, and trial fittinig and determined that 15/16" spacers are what was needed between the baffle and spar doubler webs. There is NO wiggle room for the row of holes in the spar doulbler, with its 1/2" flange. I used a couple of 3/16" steel rods spanwise, overlaid perpendicularly with several pieces of 3/4" square tubing from the hardware store. It makes for a very stable platform for the baffle. I seem to remember inspiration for the idea from Vince Frazier's Rocket website. Lots of good ideas there, including pop riveting the baffle in place before fitting and drilling the skin.;)
Click to expand...
Sounds Like a superb idea! I am going to Lowes! I havent heard of the Vince Frazier site, do you have a web address?

Thanks a Million!!

Rich
 
rulmen said:
Sounds Like a superb idea! I am going to Lowes! I havent heard of the Vince Frazier site, do you have a web address?

Thanks a Million!!

Rich
Click to expand...

You are quite welcome! Vince's website is about his Rocket build, but construction of the wings is the same as RV-4's and RV-6's. On review of the info on his site, I see that he didn't use the spacers on the Rocket, but he did use pop rivets through the baffle at each rib locaton. Van's instructions call for wood spacers which would be difficult to get consistent enough in thickness for those of us without woodworking equipment. No problem in that regard with the rods and square tubing.

The link to Vince's wing page is http://vincesrocket.com/Construction Notes for the tail and wings.htm . The tanks are about half way down the page.
 
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