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  #1  
Old 02-04-2016, 05:04 PM
Andy who? Andy who? is offline
 
Join Date: Jun 2013
Location: Royal Oak, MI
Posts: 26
Default Fluting Rudder stiffeners?

Building my 7 Time Machine........

I have all my Rudder stiffeners trimmed and ready to go but they have a bow in them like a rib would and don't sit flat on the skin. I see some build sites that have no flutes and some that have flutes on both flanges. I'm paranoid that the thin rudder skin will take the shape of the bowed stiffeners. In my mind I wouldn't want to put a flute (kink) in the vertical rib (no holes) used to stiffen the skin. Maybe after dimples and rivets everything will be flat? What say the masses?

I did search on Rudder stiffeners but didn't see much on this particular subject.
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  #2  
Old 02-04-2016, 05:34 PM
wirejock's Avatar
wirejock wirejock is offline
 
Join Date: Oct 2005
Location: Estes Park, CO
Posts: 5,203
Default Flute

Which way are they bowed? Photo please.
I didn't need to flute mine.
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Donated 12/01/2021, plus a little extra.
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  #3  
Old 02-04-2016, 06:58 PM
Andy who? Andy who? is offline
 
Join Date: Jun 2013
Location: Royal Oak, MI
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Default

Haven't sorted out pics yet. If I set them in place on the skin the center of the stiffener rides up off the skin. The middle of the longest one rides up a good 1/8th inch off the skin. They cleco onto the skin easy enough. Just wondering if they will suck the rudder skin in if I leave them that way and finish building.
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  #4  
Old 02-04-2016, 07:40 PM
wirejock's Avatar
wirejock wirejock is offline
 
Join Date: Oct 2005
Location: Estes Park, CO
Posts: 5,203
Default Flute

If they are high in the middle, flute them. You want them to lie flat. Sometimes dimpling makes them bend.
1/8" is not much. My guess is a few tiny flutes will bring them down. Try one.

I went way over the top. I match drilled mine to a particle board then after prep work, prosealed them to the skin with clekos on the board and left it for a few days before riveting.
Did the same with the elevator stiffeners.
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Larry Larson
Estes Park, CO
wirejock at yahoo dot com
Donated 12/01/2021, plus a little extra.
RV-7A #73391, N511RV reserved (3,000+ hours)
Empennage, wings, fuse, finishing kit done. Working FWF
Disclaimer
I cannot be, nor will I be, held responsible if you try to do the same things I do and it does not work and/or causes you loss, injury, or even death in the process.
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  #5  
Old 11-05-2018, 07:52 PM
tswanson tswanson is offline
 
Join Date: Aug 2016
Location: Tremont
Posts: 25
Default Same thing...

Well I saw the same result when fluting my rudder stiffeners. The longer ones bow up about 0.100”. What is the conventional wisdom on fluting the side of the flute opposite of the side with the holes? This is the side of the stiffener that carries the compressive load when the skin is compressed. At that point that section is in compression, in which case generally you don’t want a zigzag shaped member, right? Am I over thinking this? Do I just put a lot of very gente flutes in them and assume that small bend doesn’t reduce strength significantly?
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Last edited by tswanson : 11-05-2018 at 07:58 PM.
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  #6  
Old 11-07-2018, 06:24 PM
tswanson tswanson is offline
 
Join Date: Aug 2016
Location: Tremont
Posts: 25
Default Anyone?

Anyone else have any suggestions?
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  #7  
Old 11-07-2018, 07:52 PM
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JonJay JonJay is offline
 
Join Date: Jan 2007
Location: Battleground
Posts: 4,348
Default

There is no reason a simple angle has to have any bow to it. If they do, manipulate them with hand seamers or reform them over the edge of a board.
They should straighten easily.
However, you started with a straight piece of angle, no bow right? So, somewhere in the process they get bowed. You can fix that.
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