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flush rivets under walkway

bobnoffs

Well Known Member
i remember talking [writing] to someone about using flush rivits on the wing skin under the walkway material . i know at least someone has done it. could i hear from you? on the forum or pm.i am at that point and it sounds like a good idea.i am looking for a part number for the rivits and any advice.
i am building eab.
 
Gesipa GSMC41-43APG

Bob - The LP4-3 rivets Van's use on the RV-12 are manufactured by Gesipa and called PolyGrip Multi-Grip rivets. The Gesipa part number is GSMD41-43APG. The specifications on the rivets are a minimum shear strength of 162 lbs. and a minimum tensile strength of 236 lbs. That is from their online catalog available as a PDF download ? mine is dated 2009. The grip range is .039 - .197.

I have been assembling my RV-12 with the flush rivet equivalent from Gesipa that are the countersunk version of the LP4-3 rivet Van?s uses ? all the specs are the same except they require dimples or countersinks in underlying surfaces ? in your case 120 degree dimples in the skins and ribs along with 120 degree machine countersinks in the spars. A whole lot of extra work. The Gesipa part number for the countersunk equivalent of the Van's LP4-3 rivet is GSMC41-43APG.

I would imagine you may be able to use the Van?s CS4-4 rivet ... however you would need to do a little research to see if the minimum grip range of that rivet will work for you. The ribs and skin are .040 and guessing the wing walk adds another .025 or so (not near the project so sure how thick it is).

If you decide to go with the Van?s CS4-4 rivets, suggest using Cleaveland dimple dies and if you go with the Gesipa rivet suggest using the Avery dimple dies. There is a small difference in the head diameters of the two rivets (CS4-4 head is a tad smaller). I found the Gesipa rivet heads sat a little proud with the Cleaveland dies and were perfect with the Avery dies.

If you do some keyword searches on my build site there are photos that show the dimple die issues I discovered. Not all that long ago I had a post titled "Not all dimples are created equal" ... or something along that line.

Hope that helps ? happy building.
 
flush rivits

hi john,
thanks for all the specs. i do remember reading something about flush rivits and dimplers on your site. i will delve further into this. i think in the step area it would be pretty painless and you would not have rivit heads wearing thru the nonslip.
 
My Painter painted the anti slip, product from Spies-Hecker;

MyKitLog

FP21102013A0001Z.jpg
 
I used wing-walk paint from Aircraft Spruce rather than the peel-and-stick pads. Much better, I think, and fairly thick. Was no need to go with flush rivets.
 
I used wing-walk paint from Aircraft Spruce rather than the peel-and-stick pads. Much better, I think, and fairly thick. Was no need to go with flush rivets.

I like that idea a lot. Plus the regular rivets will help give traction in wet weather.

To the OP I'm assuming you're buiding EAB since I don't think you could change out the rivet styles if building ELSA.,

Jim
 
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My painter used a thick nonskid paint on the wing walk too. No chance of seeing the rivets under that desert sand. ;)
 
Bob - The LP4-3 rivets Van's use on the RV-12 are manufactured by Gesipa and called PolyGrip Multi-Grip rivets. The Gesipa part number is GSMD41-43APG. The specifications on the rivets are a minimum shear strength of 162 lbs. and a minimum tensile strength of 236 lbs. That is from their online catalog available as a PDF download … mine is dated 2009. The grip range is .039 - .197.

I have been assembling my RV-12 with the flush rivet equivalent from Gesipa that are the countersunk version of the LP4-3 rivet Van’s uses … all the specs are the same except they require dimples or countersinks in underlying surfaces … in your case 120 degree dimples in the skins and ribs along with 120 degree machine countersinks in the spars. A whole lot of extra work. The Gesipa part number for the countersunk equivalent of the Van's LP4-3 rivet is GSMC41-43APG.

I would imagine you may be able to use the Van’s CS4-4 rivet ... however you would need to do a little research to see if the minimum grip range of that rivet will work for you. The ribs and skin are .040 and guessing the wing walk adds another .025 or so (not near the project so sure how thick it is).

If you decide to go with the Van’s CS4-4 rivets, suggest using Cleaveland dimple dies and if you go with the Gesipa rivet suggest using the Avery dimple dies. There is a small difference in the head diameters of the two rivets (CS4-4 head is a tad smaller). I found the Gesipa rivet heads sat a little proud with the Cleaveland dies and were perfect with the Avery dies.

If you do some keyword searches on my build site there are photos that show the dimple die issues I discovered. Not all that long ago I had a post titled "Not all dimples are created equal" ... or something along that line.

Hope that helps … happy building.
This is fabulous information John, good job on the research! I can't get your web site to come up, has it been taken down?

It occurred to me that I could dimple certain sections and use the flush (120°) version of the LP4-3, sounds like it's been done before. Anyone out there has experience doing this? Can both the ribs and skin be dimpled and nested with 120° dimple dies?
 
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Randy, the rv-12iS (and I suppose the latest iterations of the rv-12) manual calls for CS4-4 (120 degree blind rivet) rivets under the wingwalk (two lines of rivets if i remember correctly). The skin came pre-dimpled from the factory and we were left to dimple the ribs underneath. The ribs themselves were the same as all the other ribs -- so there wasn't any change in rivet pitch along those lines, etc.
 
Randy, the rv-12iS (and I suppose the latest iterations of the rv-12) manual calls for CS4-4 (120 degree blind rivet) rivets under the wingwalk (two lines of rivets if i remember correctly). The skin came pre-dimpled from the factory and we were left to dimple the ribs underneath. The ribs themselves were the same as all the other ribs -- so there wasn't any change in rivet pitch along those lines, etc.
Thanks, good to know. I assume you're looking at drawing 17, rev 2, 03/14/18. My understanding is that the wings are the same for -12 and -12iS, but since this drawing is newer perhaps it was rev'd along the way for both applications.
 
Randy -

To be clear ... the rivets called out to rivet the wing walk doubler on earlier "legacy" versions of the RV-12 were originally the low dome LP4-3 rivets.

Apparently Van's has changed the rivet callout on the wing walk doubler to a CS4-4 rivet which is good... it will prevent the wing walk anti-skid material covering the wing walk area from prematurely wearing through at the rivet heads like it does with the LP4-3 rivets.

(Of course, as you know, flush rivets were used on my entire wing not just the wing walk doubler area).

Happy building,
 
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Fush

Was looking at my original plans from 2014 and I just missed the update for the flush rivets on the Dec 2016 revision, I was at that step in November 2016. I don't have any plans to change. I think I will eventually use paint on wing walk on final paint.

o7e.png
 
Radical idea

Well here's a radical idea: why not just use CS4 rivets on the entire wing skin back to and including the fwd spar? Of course not with an E-LSA, but I'm going E-AB, hmmm.
 
I could be wrong, but I THINK the CS4-4's don't have quite the same strength as LP4-3's.

I don't think CS4-4's are made by Gesipa, but I'd love to see the spec sheet to confirm.. or deny.
 
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