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Machine C/S vs. Dimpling fuel tank baffle flange

J

jdmunzell

Well Known Member
Okay, so I missed this on the plans.. I am about to close up the right fuel tank and when originally dimpling the wing tank skin, I wound up dimpling all the holes in the skin, including the spanwise holes that mate up to the rear baffle flange. DOH!! The plans show that the skin should be countersunk then mated to the baffle flange. Dimpling the baffle flange is going to mean having to shave down the female die in order to fit up against the main baffle while dimpling the flange. I can do that or just C/S the baffle flange in order to accept the already dimpled tank skin. Both surfaces are of the same thickness and I believe this to be key here.

What would guys do here? Dimple the baffle flange or countersink it??

Jeff
-8 wings...STILL UGH!
 
Dimple

jdmunzell said:
Okay, so I missed this on the plans.. I am about to close up the right fuel tank and when originally dimpling the wing tank skin, I wound up dimpling all the holes in the skin, including the spanwise holes that mate up to the rear baffle flange. DOH!! The plans show that the skin should be countersunk then mated to the baffle flange. Dimpling the baffle flange is going to mean having to shave down the female die in order to fit up against the main baffle while dimpling the flange. I can do that or just C/S the baffle flange in order to accept the already dimpled tank skin. Both surfaces are of the same thickness and I believe this to be key here.

What would guys do here? Dimple the baffle flange or countersink it??

Jeff
-8 wings...STILL UGH!
Click to expand...

Do a search. I think you'll find this is a common error and some actually prefer to build tanks that way. Dimpled baffle.
Always ask Vans to be sure.
 
The hard part dimpled is the squeegee of the sealant as you slide the baffle on. The dimples will make an interference as the baffle is slid down and extra care would be needed to not have a sealant gap in that process. But a number of people dimpled anyway. I think that is the main thing.

Second thing at least in the RV14 plans is to leave every 10th hole or so unsunk and to do it after the sealant dries. I think this is to keep locator holes in proper position when first placed. Might be some play in the part if you don't do this - but I'm just thinking that is why.
 
It does seem to me that dimpling the baffle to fit the already dimpled skin would make for a stronger joint especially in sheer strength.. I'll check with Vans in the morning just the same but I do think I'll dimple.
 
Sealant

JDA_BTR said:
The hard part dimpled is the squeegee of the sealant as you slide the baffle on. The dimples will make an interference as the baffle is slid down and extra care would be needed to not have a sealant gap in that process. But a number of people dimpled anyway. I think that is the main thing.

Second thing at least in the RV14 plans is to leave every 10th hole or so unsunk and to do it after the sealant dries. I think this is to keep locator holes in proper position when first placed. Might be some play in the part if you don't do this - but I'm just thinking that is why.
Click to expand...

Just be careful as Dudley mentions above.
 
I would dimple the skins and baffle. I followed the plans on my first set, but over CS is a common error. If the rivets work they can leak later. IMO you are better to dimple and work a little harder to seal them.

In general I try to dimple anywhere I can reasonably do so. Less working rivets.
 
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