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12-16-2015, 06:05 AM
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Join Date: Jan 2011
Location: SoCal
Posts: 391
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Kudos!
Arlie-
I know this puzzler was frustrating; lots of us were silently watching you work it.
Congrats on sticking to it!
__________________
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VAF dues paid though exempt
RV-9A sold (I miss that bird!)
RV10 sold (miss that one too!)
RV-14A build underway
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12-16-2015, 12:22 PM
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Join Date: Dec 2009
Location: Montreal
Posts: 1,456
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Quote:
Originally Posted by acam37
Today I was sitting in my hangar looking at my ailerons, asking the question "what would cause the aileron to balloon and flex in flight?" And then it dawned on me, The Stiffeners. So I went and took a closer look. What did I find? The stiffeners terminate approx. 3" from the trailing edge, so this could explain a lot. I went ahead and squeezed the trailing edge radius from 3/16" down to 1/8" which tightened the skin a little and straightened it up a bunch. Justin took it up and voila. He said that made a 100% difference in the stick forces. I am still going to build a new set of ailerons, but at least I think I finally solved this mystery.
[IMG]  [/IMG]
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It is amazing and non intuitive how much the trailing edge shape changes the flying qualities. I am sure some airplanes, particularly very small ones like the hummel bird, have been lost because of this.
__________________
Scott Black
Old school simple VFR RV 4, O-320, wood prop, MGL iEfis Lite
VAF dues 2020
Instagram @sblack2154
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12-16-2015, 02:14 PM
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Join Date: Feb 2005
Location: 20km outside of Zurich, Switzerland
Posts: 468
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Buy a set of plans, it is your plane, YOU are responsible for it!
Hello Arlie
Congratulation for you buying an RV-4 and rebuilding them.
It is not the first time here on VAF, that someone bought a plane and having difficulties with it. You found with the help of VAF and your testpilot the root cause.
I just can highly recommend to change all the important parts, so that they exactly are looking like the plans from Vans describe them. It is now your plane, you are responsible for it!
Flying an RV is one part, the community around another ... both are wonderfull! You are at the right place here on VAF!
Btw, there are not so many RV-4 crashes, but those that happend are often loaded to heavy, behind the rear CG limit and doing aerobatics! It is a cross country plane for two, but only a single aerobat machine.
Take care and enjoy!
__________________
Dominik
RV-7A, TMX-IO-320, FM-150, Sensenich FP
Flying since 28. April 2016
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12-16-2015, 02:18 PM
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Senior Curmudgeon
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Join Date: Sep 2005
Location: Dayton Airpark, NV A34
Posts: 15,420
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Quote:
Originally Posted by acam37
Today I was sitting in my hangar looking at my ailerons, asking the question "what would cause the aileron to balloon and flex in flight?" And then it dawned on me, The Stiffeners. So I went and took a closer look. What did I find? The stiffeners terminate approx. 3" from the trailing edge,
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Actually, the rivets terminate at that point, the actual stiffener continues a bit more toward the TE.
__________________
Mike Starkey
VAF 909
Rv-10, N210LM.
Flying as of 12/4/2010
Phase 1 done, 2/4/2011 
Sold after 240+ wonderful hours of flight.
"Flying the airplane is more important than radioing your plight to a person on the ground incapable of understanding or doing anything about it."
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12-16-2015, 02:33 PM
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Join Date: Jan 2007
Location: Benton, Kansas
Posts: 259
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Maybe they do, maybe they don't...
Quote:
Originally Posted by Mike S
Actually, the rivets terminate at that point, the actual stiffener continues a bit more toward the TE.
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Maybe, maybe not! With the flex that Arlie was describing, I bet they don't go as far back as they SHOULD.
I looked at mine, the last rivet is about an inch from the TE. The stiffener goes back another .75" IIRC.
__________________
Gregg J. Brightwell
Benton, KS
CFII/MEII, ATP, AGI, A&P
-4 Emp and Wings complete!
Fuselage out of the jig!
www.mykitlog.com/gbrightwell
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12-16-2015, 02:35 PM
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Join Date: Aug 2012
Location: Lufkin Tx
Posts: 689
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Quote:
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Actually, the rivets terminate at that point, the actual stiffener continues a bit more toward the TE.
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Mike, I don't think so in this case. As I described earlier, you can actually manipulate the entire trailing edge by hand. Even where the stiffeners are "supposed to be" in either case, it ain't right. I just don't know why I didn't notice this earlier?
__________________
Arlie Conner (A&P)
RV-4 (N124TT) Sold
RV-8 (N269CP) Sold
RV-4 (N684ML) completed 3-17-19
KOCH Nacogdoches
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12-16-2015, 02:45 PM
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Senior Curmudgeon
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Join Date: Sep 2005
Location: Dayton Airpark, NV A34
Posts: 15,420
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Quote:
Originally Posted by Gregg Brightwell
Maybe, maybe not! With the flex that Arlie was describing, I bet they don't go as far back as they SHOULD. 
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Gregg------I have no idea how far the stiffeners are designed to go, (notice I used the term "a bit" -----carefully chosen word to give me wiggle room  ) I was just pointing out that the end of the stiffener and the location of the rivet are not necessarily relative.
Gonna take x-ray vision or a can opener to tell for sure.
__________________
Mike Starkey
VAF 909
Rv-10, N210LM.
Flying as of 12/4/2010
Phase 1 done, 2/4/2011 
Sold after 240+ wonderful hours of flight.
"Flying the airplane is more important than radioing your plight to a person on the ground incapable of understanding or doing anything about it."
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12-16-2015, 06:26 PM
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Join Date: Dec 2014
Location: Just Minutes from KBVI!
Posts: 1,039
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Quote:
Originally Posted by Mike S
Gonna take x-ray vision or a can opener to tell for sure.
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Not necessarily...
It may be possible to do it a different way. If you can find a chest or walk-in freezer big enough, freeze the aileron. Then take it out and apply a warm rag a couple inches away from the stiffener on both sides (but don't cover it) just enough to warm the skin. Then breathe on the area. You may be able to see the outline of the stiffener where frost forms from your breath due to the larger thermal mass of the stiffener holding a lower temperature for longer than the thin skin.
Just a thought.
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12-16-2015, 07:07 PM
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Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 9,035
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It doesn't really matter how long the stiffeners are
if there is no rivet near the aft end.
The stiffener effectively ends at the last rivet.
__________________
Opinions, information and comments are my own unless stated otherwise. They do not necessarily represent the direction/opinions of my employer.
Scott McDaniels
Van's Aircraft Engineering Prototype Shop Manager
Hubbard, Oregon
RV-6A (aka "Junkyard Special ")
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12-16-2015, 07:07 PM
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Join Date: Jan 2012
Location: up up and away
Posts: 312
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made me wonder so I just looked at my rv4 plans

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