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03-05-2015, 09:36 AM
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Join Date: Jun 2013
Location: Des Moines, IA
Posts: 255
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Aileron twist correctable?
I just finished riveting the bottom skin to the spar and thought I better take a look at where I stand. This is what I see with the right and left ailerons respectively.
The right aileron was off on the end rib hole alignments. Using a punch I was able to line the holes up but even with the clecos in I have this twist. I am guessing the spar got twisted somehow, maybe from the counterbalance/nose rib assembly since that process seemed pretty hokey to me.
My question is can I fix this twist during the trailing edge riveting or do I need to do something else now to correct this. What can I do?
Thanks,
Jim
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03-06-2015, 08:24 AM
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Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 9,035
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Any aircraft assembly becomes torsionally stiff along its span when any boxed section of it is closed.
In the case of the aileron, once the fwd "D" cell (box) of the aileron is closed, it pretty much locks in what ever span wise alignment you have.
It should be correctable if you un-rivet the bottom flange of the spar and then re-rivet while maintaining alignment.
__________________
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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03-06-2015, 12:16 PM
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Join Date: Jan 2005
Location: Ontario, Canada
Posts: 1,544
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Check out this thread http://www.vansairforce.com/communit...d.php?t=119642
To fix this you will have to drill out rivets as suggested but by using the method suggested in the above thread you should be able to avoid this problem.
__________________
Tom Martin RV1 pilot 4.6hours!
CPL & IFR rated
EVO F1 Rocket 1000 hours,
2010 SARL Rocket 100 race, average speed of 238.6 knots/274.6mph
RV4, RV7, RV10, two HRIIs and five F1 Rockets
RV14 Tail dragger
Fairlea Field
St.Thomas, Ontario Canada, CYQS
fairleafield@gmail.com
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03-06-2015, 12:58 PM
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Join Date: Jun 2013
Location: Des Moines, IA
Posts: 255
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Thank you guys. I guess my next question is how do I prevent this from happening again. I understand in the thread linked clecoing the TE in and then the spar/bottom skin should align the aileron (I will check it on my granite table again). My guess is that as soon as I uncleco the TE and get my ape arm in there the aileron will twist again while I am riveting. Is there a good way to hold the aileron in the cradle?
In the mean time I'll get going on those bottom skin/spar rivets.
Also forgot to mention. My twist ended up being 3/16" (I noticed in the picture the ruler is unreadable).
Last edited by HeliCooper : 03-06-2015 at 01:01 PM.
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03-06-2015, 01:36 PM
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Join Date: Jan 2005
Location: Ontario, Canada
Posts: 1,544
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Clecoe it together lined up as I describe, on your wing. Put it in the cradle,holding it in place with foam, etc, and do three or four rivets spread out along the spar. Take it out of the cradle and check on the wing. If all is well stick a few more rivets in. It is possible that your cradle is twisted and holding the aileron too tight. If it is cleoced together straight foam pieces wedged in the cradle should hold it from twisting. Make sure the cradle is not the problem.
__________________
Tom Martin RV1 pilot 4.6hours!
CPL & IFR rated
EVO F1 Rocket 1000 hours,
2010 SARL Rocket 100 race, average speed of 238.6 knots/274.6mph
RV4, RV7, RV10, two HRIIs and five F1 Rockets
RV14 Tail dragger
Fairlea Field
St.Thomas, Ontario Canada, CYQS
fairleafield@gmail.com
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03-06-2015, 02:22 PM
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Join Date: Jun 2013
Location: Des Moines, IA
Posts: 255
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Thanks Tom,
I'll give it another go. The weird thing is the left aileron came out perfect. Maybe just got lucky on that one.
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03-06-2015, 05:07 PM
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Join Date: Jun 2013
Location: Des Moines, IA
Posts: 255
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Saga continues
I removed all bottom skin/spar rivets and right away noticed that without the bottom skin on the same twist is still evident. I decided to try and correct this by using a similar method to Tom's. I clecoed the TE and bottom and top skins. I then clamped the aileron to my table top and then clecoed the bottom skin to to spar. As soon as I remove the clamp the twist immediately returns to the aileron. I even went as far as putting in a negative (relative to the current) twist while it the aileron was clamped and then clecoing. The twist returns back to the same 3/16" every time.
The only idea I can come up with is to clamp the top skin/main ribs down with 0 twist and reach in and set some rivets to see if the rivets will hold out the twist. Does anyone have any better suggestions?
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03-06-2015, 07:10 PM
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Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 9,035
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Quote:
Originally Posted by HeliCooper
I removed all bottom skin/spar rivets and right away noticed that without the bottom skin on the same twist is still evident. I decided to try and correct this by using a similar method to Tom's. I clecoed the TE and bottom and top skins. I then clamped the aileron to my table top and then clecoed the bottom skin to to spar. As soon as I remove the clamp the twist immediately returns to the aileron. I even went as far as putting in a negative (relative to the current) twist while it the aileron was clamped and then clecoing. The twist returns back to the same 3/16" every time.
The only idea I can come up with is to clamp the top skin/main ribs down with 0 twist and reach in and set some rivets to see if the rivets will hold out the twist. Does anyone have any better suggestions?
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If the L.E. is already riveted to the counter balance, it will also contribute some torsional stiffness.
What you are proposing is what I would do.
__________________
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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03-07-2015, 09:19 AM
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Join Date: Jun 2013
Location: Des Moines, IA
Posts: 255
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The LE is not riveted to the counter balance. I clamped the aileron down flat and put in 10 rivets along the span. I check where I was at and it looks like I still have a 1/8" twist. I'm at a loss of what to do with it now. I put bolts through the mounting holes and those are lined up. It seems if I try to negate the twist too much it pulls these holes out of alignment and the bolt wants to go in crooked. At this point do I need to just accept the 1/8" twist?
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03-07-2015, 01:25 PM
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Join Date: Jan 2005
Location: Ontario, Canada
Posts: 1,544
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Did you mount it on the wing and check it there?
__________________
Tom Martin RV1 pilot 4.6hours!
CPL & IFR rated
EVO F1 Rocket 1000 hours,
2010 SARL Rocket 100 race, average speed of 238.6 knots/274.6mph
RV4, RV7, RV10, two HRIIs and five F1 Rockets
RV14 Tail dragger
Fairlea Field
St.Thomas, Ontario Canada, CYQS
fairleafield@gmail.com
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