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  #1  
Old 10-15-2018, 12:12 PM
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mulde35d mulde35d is offline
 
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Default Elevator Trailing Edge Gap

While finishing up my right elevator I noticed this gap between the inboard rib and the trailing edge. I am not talking about the fact that it is open (since it is supposed to be) but rather the bend in the metal skin between the aft end of the rib and the trailing edge. When relaxed it bends outward, when pressed with my finger in bends inward. When I release the metal it make the distinctive pop as it bends back outward.

I am thinking I will place some pro-seal on the last quarter inch of rib (between the rib and skin) to hold the metal skin inward. Any other thoughts on the topic would be greatly appreciated.

Not completely sure how this manifested itself (I am thinking it is how the proseal on the foam rib dried to the skin), but figure it is more of an annoyance than a structural issue as long as it doesn't fatigue over time from movement back and forth.



Pictures didn't load, will post them tonight on a different computer
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RV-14A #140512: Empennage in Progress

Last edited by mulde35d : 10-15-2018 at 12:16 PM.
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Old 10-15-2018, 12:19 PM
rocketman1988 rocketman1988 is offline
 
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Default Tailing edge

Are you sure the trailing edge wedge is installed in the correct direction?

In the photos it looks as if it is installed backwards...
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  #3  
Old 10-15-2018, 12:29 PM
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bkervaski bkervaski is online now
 
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Quote:
Are you sure the trailing edge wedge is installed in the correct direction?

In the photos it looks as if it is installed backwards...
Quote:
Your wedge is backwards.

The thin side should be aft and the thick side fwd.
Not on the 14 .. the depicted installation direction is correct.

Had a long discussion with the mothership about this during my factory tour. The prototype 14 had an undesirable mushy stick feel in some conditions that was resolved by this trailing edge design departure from previous RVs.
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Last edited by bkervaski : 10-15-2018 at 12:36 PM.
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  #4  
Old 10-15-2018, 12:47 PM
Tom023 Tom023 is offline
 
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Quote:
Originally Posted by bkervaski View Post
Not on the 14 .. the depicted installation direction is correct.
.
Concur, your wedge is installed correctly. This is where I like having the plans in PDF and an iPad. You can zoom in areas and get good detail if necessary. The drawings clearly show the thin side of the edge inward.
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  #5  
Old 10-15-2018, 01:22 PM
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mulde35d mulde35d is offline
 
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Default Skin

You all nearly gave me a heart attack with the whole backwards wedge thing.

Now back to the skin bulge? thoughts
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Old 10-15-2018, 01:49 PM
rvbuilder2002 rvbuilder2002 is offline
 
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Quote:
Originally Posted by mulde35d View Post
While finishing up my right elevator I noticed this gap between the inboard rib and the trailing edge. I am not talking about the fact that it is open (since it is supposed to be) but rather the bend in the metal skin between the aft end of the rib and the trailing edge. When relaxed it bends outward, when pressed with my finger in bends inward. When I release the metal it make the distinctive pop as it bends back outward.

I am thinking I will place some pro-seal on the last quarter inch of rib (between the rib and skin) to hold the metal skin inward. Any other thoughts on the topic would be greatly appreciated.

Not completely sure how this manifested itself (I am thinking it is how the proseal on the foam rib dried to the skin), but figure it is more of an annoyance than a structural issue as long as it doesn't fatigue over time from movement back and forth.



Pictures didn't load, will post them tonight on a different computer
Is that one of the foam ribs visible inside?

If so, it doesn't look like it is entirely bonded to the skin and it looks like it is a bit too tall, causing the skins to be spread apart. The aft end of the foam rib should be about the same height as the fwd edge of the T.E. wedge so that there is a neutral transition from the on onto the other.
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  #7  
Old 10-15-2018, 02:06 PM
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mulde35d mulde35d is offline
 
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Default Photo

I didn't notice it while looking at the Elevator, but in the picture it does appear to be de-bonded. I will take a look tonight, but the Trailing edge is nice and straight with no bulging at the transition between the foam rib and the trailing edge filler. It almost seems as if the entire trailing edge is about 1/8 to 1/4" too low, but it is only manifesting itself at the inboard rib with the bulge as seen in the picture. That is why I am a bit perplexed. The real question is do I simply accept it as a flaw and move on, or could it have greater implications that I am not tracking. For now, I am thinking pro-seal as best possible and move on.

Valid point to consider though. If the foam ribs were too thick then it would shorten the distance of the skin from the rear spar to the trailing edge. I had trimmed the foam ribs exactly to the template, but never checked the trailing edge thickness against the trailing edge filler piece. May be worth adding this step for anyone approaching this portion of the build as that is likely the cause of the skin bulge that is present on the inboard rib.

Any aero or mechanical engineers have thoughts on long term effect of this in regards to performance or structural fatigue life.
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RV-14A #140512: Empennage in Progress

Last edited by mulde35d : 10-15-2018 at 03:10 PM.
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  #8  
Old 10-16-2018, 07:22 AM
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bkervaski bkervaski is online now
 
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Is it just bellowing towards the end as pictured? If so, you can probably bond that rib back into place without much fuss .. just squeeze some pro-seal in there and use a clamp to keep it together ..
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Last edited by bkervaski : 10-16-2018 at 07:24 AM.
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  #9  
Old 10-16-2018, 07:37 AM
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mulde35d mulde35d is offline
 
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I looked last night and the foam rib in the picture is slightly de-bonded in the middle. Also, the rib is the correct thickness as the two photos I posted earlier were simply at a bad angle and made the rib appear thicker at the trailing edge. Of note, their is about a quarter inch gap from the aft edge of the foam rib to the leading edge of the trailing edge wedge (I know, tough to follow that sentence) which accounts for variation in thickness from the foam rib to the trailing edge piece.

I will inject some pro-seal near the de-bonded foam rib along with between the metal rib / skin, clamp, and move on. No real performance or structural issues that I can imagine moving forward. Thanks for the input
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RV-14A #140512: Empennage in Progress

Last edited by mulde35d : 10-16-2018 at 06:31 PM.
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Old 10-16-2018, 11:17 AM
Tom Martin Tom Martin is offline
 
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Before you bond the parts, clamp some angles, or similar straight flat surface, to the top and bottom skins. This will insure alignment.
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