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Old 08-18-2016, 05:12 AM
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NorthernRV4 NorthernRV4 is offline
Join Date: Mar 2013
Location: Prince Edward Island, Canada
Posts: 124
Default Inboard/Outboard wingskin joint

Does anyone have some tricks for a nice joint where the outboard skin joins with the inboard? I have my original plans which show a simple lap joint with the inboard lapping over the outboard. The new plans show the outer lapping over the inboard. Simple enough. The overhang aft out the rear spar is notched make for a simple butt joint aft of the spar. I was looking at a friends -4 and his has the notch/butt joint at both spar areas with the outboard skin tucking under the inboard. Has anyone joggled the outboard .025 skin to create a smoother transition? How would one go about this for such a long section? I'm not sure it's worth the effort. I already have the Cleaveland edge roller tool to create the slight downturned edge and I think I would chamfer the top edge a little more to reduce the step.
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Old 08-18-2016, 05:47 AM
HFS HFS is offline
Join Date: Aug 2009
Location: Lemoore, CA
Posts: 230
Default FWIW

I did what you are contemplating, but with the overlap of the belly skin on -3 I am building.

I also have built a -4 and did a simple overlap on the wing skins. These two skins have about the same width - so the comparison is valid. I did the "joggle" on the -3 because of some underlying skeletal issues that made doing so better from a skin conformation standpoint - more of an assembly issue that strictly cosmetic. After all, no matter what, you still have an overlap.

Since the belly skin, being on the bottom, never shows (except for low inverted passes), cosmetic concern was not an issue. All said and done, the simple overlap looks better, the joggled joint gives better skin fit when underlying skeleton issues dictate its use.

Take the above advice for what you paid for it.

David Howe
RV4 S/N 1136
HR II S/N 002
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Old 08-18-2016, 06:17 AM
fixnflyguy fixnflyguy is offline
Join Date: Jan 2006
Location: Winston-Salem, N.C.
Posts: 926
Default Single piece upper skins

I built my -4 with single piece upper skins (.032"), as did 2 other builders in my area building -6's. I was able to order my wing kits without the standard upper skins, and locally procured the sheets of .032" which I trimmed to size. Cost me about $300.00, but I was also discounted on my kits for the standard skin deletions.. I used the standard 2 piece lower skins, which are unseen. Also, the upper lap can cause a wear spot on the flap if done improperly. I wouldn't suggest the joggle, but do recomend tapered shims at the splice where it attaches to the will have a much nicer finish/transition than without. Can be made with some scrap sheet and a die grinder/sander if you dont have access to tapered shim material.
Bill E.
8A7 / Advance NC
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Old 08-18-2016, 06:59 AM
WenEng WenEng is offline
Join Date: Aug 2008
Location: Jacksonville, FL
Posts: 514
Default Here is what I did..

Originally Posted by NorthernRV4 View Post
Does anyone have some tricks for a nice joint where the outboard skin joins with the inboard?........
Wendell VAF#1832
RV-6A 3/4 done...N48JE Reserved
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Donated to VAF in 2017
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Old 08-18-2016, 09:54 AM
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az_gila az_gila is offline
Join Date: Jan 2005
Location: 57AZ - NW Tucson area
Posts: 9,606

The plans call for a staggered layout for the two rows of rivets at the skin overlap which is standard aircraft practice.

Is there a reason you lined the rivet rows up?
Gil Alexander
EAA Technical Counselor, Airframe Mechanic
Half completed RV-10 QB purchased
RV-6A N61GX - finally flying
Grumman Tiger N12GA - flying
La Cholla Airpark (57AZ) Tucson AZ
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Old 08-18-2016, 10:04 AM
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NorthernRV4 NorthernRV4 is offline
Join Date: Mar 2013
Location: Prince Edward Island, Canada
Posts: 124

Thanks fellas, so WenEng, you notched both front and rear corners of the .032 inboard skin and lapped the outboard on top. Looks like it makes a nice transition to the leading edge skin without filing away the corner like the manual says. I wonder if there is an appreciable reduction in strength by not tying the skins together here. This seems very similar to my friends -4 except his outer skins are the one with the notches and the inboard laps over the outboard. Nearly 600 hours on his with some light acro so obviously not an issue.
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Old 08-18-2016, 10:37 AM
SgtZim SgtZim is online now
Join Date: May 2015
Location: Crittenden, ky
Posts: 182

I know some folks have done that - notched out a piece of the skin at the overlap joint, but I would absolutely not recommend that unless Van's or a real engineer did a full structural analysis on it. The fact that some planes are flying and logging hours and have done light acro is not the same.

There are pretty solid reasons that the manuals specify minimum edge distances, minimum thicknesses, etc.
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Old 11-08-2017, 07:04 PM
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NorthernRV4 NorthernRV4 is offline
Join Date: Mar 2013
Location: Prince Edward Island, Canada
Posts: 124

I'm resurrecting this thread because I'm at a decision point where I need to notch either the inboard or outboard skin. There is conflicting information on the drawings which leads me to believe Van changed the method over the years, I just don't know why. It seems the current standard is outboard over inboard and trim the aft corner out of the inboard. The only reason I can think of is that the outboard skin hides the fwd corner of the thicker inboard skin that you must taper to get a nice flush(ish) finish with the leading edge skin. No?
2017 VAF dues happily paid, Thanks DR!
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Old 11-08-2017, 07:13 PM
Kyle Boatright Kyle Boatright is offline
Join Date: Aug 2005
Location: Atlanta, GA
Posts: 3,323

If you lap the outboard over the inboard, you're reducing the chance of water intrusion into your wings.

If you trim (notch) the underlying skin, it makes a better looking joint than notching the top skin. Notch the one on top, and that notch stares at you forever...
Kyle Boatright
Atlanta, GA
2001 RV-6 N46KB
2019(?) RV-10
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Old 11-09-2017, 05:52 AM
RogerG RogerG is offline
Join Date: Dec 2011
Location: Lubbock, TX
Posts: 60

Later plans indicate outboard over inboard, however when I contacted Vans I was told your choice. Since my left wing was already built with inboard over outboard by previous builder I continued the same on the right wing.

If I were starting from beginning, I would use outboard over inboard. Just makes more since, water running down the wing would not have the tendacy to go under this lap joint.

Somewhere possibly Rvaviator it was recommended that the outer skin edge be filed to create a smoother transition at the lap, then edge roll. At the leading edge filing both skins at the lap will reduce the material thickness just enough to make the transition smoother but not perfect. A notch of the underlying skin at leading edge might work better.
Roger Graham
Lubbock TX
RV-4 Under Construction
VAF Dues Paid 2018
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