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03-22-2017, 06:50 PM
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Join Date: Feb 2008
Location: Calgary, Alberta
Posts: 1,005
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Yep, guess it's up to who you get on the tech line.
I like the idea of Tinnerman washers too.
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Ralph
built a few RVs, rebuilt a few more, hot rodded some, & maintained/updated a bunch more
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03-23-2017, 04:34 AM
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Join Date: Apr 2012
Location: Collierville, TN (KFYE)
Posts: 1,433
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Perhaps the way to look at it is that those fairings are certainly aerodynamic if not truly structural. I've heard a story from a reliable source that flying the plane without them installed makes the plane almost uncontrollable. Don't ask me why this happened...wasn't me. My aft-most hole on the bottom didn't match well and I had to elongate the hole in the fairing and use stainless tinnerman washers to finish the job. Stainless and aluminum will corrode, so prime the inner surface of the washers.
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RV-8 #81077 Super Slow Build
Dynon Skyview HDX, Titan IOX-370, Dual P-Mags, AFP FM200A FI, Whirlwind 200RV CS Prop
First Flight 11/20/2016
www.marksrv8.com
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03-23-2017, 05:44 AM
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Join Date: Feb 2010
Location: Gardnerville Nv.
Posts: 2,828
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Not an engineer nor did I stay at a Holiday Inn Express last night.....but, I can see this adding to + G strength with the bottom skin all connected in tension 
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7A Slider, EFII Angle 360, CS, SJ.
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03-23-2017, 06:10 AM
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Join Date: Jun 2005
Posts: 846
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screws
Yep I went to search and found lots of info on this subject as I had a ? a few years ago on this same subject.The RV3,4,6 were load tested with out screws in place and 7,8,9 with screws in place so yes they are part of the wing!
Bob
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03-23-2017, 07:53 AM
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Join Date: Sep 2007
Location: Central IL
Posts: 5,516
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Quote:
Originally Posted by bret
Not an engineer nor did I stay at a Holiday Inn Express last night.....but, I can see this adding to + G strength with the bottom skin all connected in tension 
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Quote:
Originally Posted by 6 Gun
Yep I went to search and found lots of info on this subject as I had a ? a few years ago on this same subject.The RV3,4,6 were load tested with out screws in place and 7,8,9 with screws in place so yes they are part of the wing!
Bob
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Odd that Gus would say not structural. Vans will compromise on cosmetics, but not safety. Maybe he assumed that they would still share the loads even if elongated, at least in this direction. He has a lot of experience and surely this discussion has been thrashed with engineering.
Anyway - although they carry some load, the pitch/spacing is not adequate for full skin load transfer, so Scott could just add screws between existing ones and move on. This addresses the strength and offset issue. OTOH - this shifts loads to the skin, and changes the load balance of the structure. Jon Jay said his screws loosened periodically for a while then stopped. So, clearly they do carry see some load, but how much they carry is open for analysis. Back to Vans.
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Bill
RV-7
Lord Kelvin:
“I often say that when you can measure what you are speaking about,
and express it in numbers, you know something about it; but when you
cannot measure it, when you cannot express it in numbers, your knowledge
is of a meager and unsatisfactory kind.”
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03-23-2017, 09:40 AM
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Join Date: Jan 2007
Location: Battleground
Posts: 4,348
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Quote:
Originally Posted by BillL
. Jon Jay said his screws loosened periodically for a while then stopped. So, clearly they do carry see some load, but how much they carry is open for analysis. Back to Vans.
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Another CI or two since that report and they are still tight. There could have been other factors at play. However, the rear spar bolt discussions and confirmation from Scott McD, that joint can move. If it can move, that belly skin must be taking some load at some point. I would suspect it isn't going to be cause or a factor in a wing failure. As you point out, there are too few screws to put that sheet to much work.
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Smart People do Stupid things all the time. I know, I've seen me do'em.
RV6 - Builder/Flying
Bucker Jungmann
Fiat G.46 -(restoration in progress, if I have enough life left in me)
RV1 - Proud Pilot.
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03-23-2017, 10:03 AM
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Join Date: Jan 2005
Location: 57AZ - NW Tucson area
Posts: 10,011
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Quote:
Originally Posted by Mark Dickens
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Stainless and aluminum will corrode, so prime the inner surface of the washers.
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Or simply take those screws and washers out when the plane is painted. 
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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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03-23-2017, 10:40 AM
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Join Date: Jan 2006
Location: South Africa
Posts: 840
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I thought they are strutural
A couple of years back I also had an RV7 in my shop without those screws. Asked Vans and the reply was: Do not attempt to fly that aeroplane as it is structural. Cannot remember who it was but I find it interesting how opinions differ 
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Jan Hanekom
South Africa
Approved Person nr 325
http://www.rvbits.com
RV10 - ZU-XOX - (Flying)
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Dues paid for 2020 WITH A SMILE
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04-02-2017, 01:21 PM
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Join Date: Nov 2014
Location: Eugene or
Posts: 39
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Screw alignment issue
Did you go back and check the angle of incidence on the wing as well as check the wing for forward and aft sweep after you ran into this problem? That is where I would start. Wing twist shouldn't be an issue with this particular problem.
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05-14-2018, 12:11 PM
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Join Date: May 2015
Location: Crittenden, ky
Posts: 194
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wondering about this too
I know this is an older post, but I'm now doing my fairings and I just match drilled those holes between the fuselage skin and wing.
My issue/question is about the fit of the overlapping skins. my fuselage skin hangs about 1/8" lower than the wing bottom, and clecoing the skins together of course causes major rippling because of the curved surface. I'm thinking about adding a filler strip between the skins just to make a clean joint, but if it is indeed structural - that would not be the best solution.
Also, if it is structural - the whole method of drilling those holes is very poor: You pre-mark lines along the wing skin and then you are supposed to take a stab at finding those holes in the wing by measuring off of those lines and back 3". Far from a good match drill. I had just enough room to squeeze in a hole duplicator, and made good matching holes, but the geometry of the two skins makes pretty bad ripples. Kind of a tradeoff between structure and aerodynamics for me anyway.
I sent my question in to Van's this am, I'll update when I get their comments.
picture of my wing/fuselage joint.
http://www.facebook.com/BZsRVproject...type=3&theater
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