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Upper wing skin/flap gap

NorthernRV4

Well Known Member
So I'm working on mounting my ailerons and flaps to my starboard wing and the upper skin doesn't follow the upper surface of the flap very well. Seems that I ended up with some waviness to the skin overhang during riveting. Just wondering if anyone else has experienced this and if they have a fix. I've tried manipulating the skin by hand as much as I feel comfortable with, anymore feels like I'm stressing the skin or spar flange. No change in the uneven line.

Thoughts?

showmy.php
 
Spar flange likely

It looks like a wave caused by the spar flange not being even. It would likely take drilling the skin loose and trying to adjust the spar flange. The skin is thin and will follow the spar flange. May not be easy, but you are at a point where now is the time to do it.
 
If those wings are from around 2005-2010 or so, then what you've got is likely a situation where the spar flange was under bent during manufacture. Van's has a loaner tool to fix that, but I was on the list to get it for months and finally gave up and made my own when I had the same issue on my RV7 wings from 2007

Just search "ski-jump wing trailing edge"
 
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Thanks gents, the spar flange is pretty even as far as I can see. The spars were purchased in about 2015. The flange being under bent could be an issue though since I noticed what seems like a bit of reflex on the top skin near the root. Curious, what does this tool that Van's offers look like? I'd consider making one.
 
Imagine a two by four with a long taper on the flat side. Now make a slice as long as the distance from the rear spar. The taper will allow you to essentially pry down on the spar flange. Pry might not be the proper term. Applying pressure, gently along the spar may help to get things laying properly.
Making a short piece of practice spar flange with a piece of simulated skin attached will allow you to see how it works and what sort of tip you need on the end of the two by four

I would suggest that hardwood may work better then softwood. This would also allow you to practice what tapping on the upper wood piece while exerting pressure would do. I had to do this to my RV4, which was an old one, kit 126, I believe. Be gentle, steady pressure is the word.

I think this was talked about in the early plans or one of the news letters
 
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If


Just search "ski-jump wing trailing edge"


The tool that you need is made of Steel. Vans should have it available, as my friend just returned it. We had borrowed it to fix this exact condition on his -8. You first mark the areas that need adjusting, remove the flap, then install the tool. You snug it up with an Alan key, then apply pressure and reinstall the flap to check your results. I also used a straight edge along the upper skin as a quick way to check progress before installing the flap.
 
Thanks gents, the spar flange is pretty even as far as I can see. The spars were purchased in about 2015. The flange being under bent could be an issue though since I noticed what seems like a bit of reflex on the top skin near the root. Curious, what does this tool that Van's offers look like? I'd consider making one.

I did this on my RV-8 wings not long ago. Here is a thread I wrote up about the tool from Vans and the process.

https://vansairforce.net/community/showthread.php?t=182751
 
For a visual, there are quite a few pix of the the tool I made and the tweaking process on my build log wing entries March 08, 2020 and May 1, 2020.

Link below my signature
 
Thank you fellas. I did a little investigating last evening and found that the spar flange does indeed had a section that has a wave to it. I placed a straight edge on the inside surface of the flange and there is a slight gap in the exact section where the skin doesn't match the flap upper surface.

If I understand this tool/process, it's something that is most often done without drilling out the rivets so that is great. While I'm quite good at drilling out rivets, I'd rather not have to.

The tool seems like something that is good to have but borrowing it from Vans, having to ship to Canada and back might be costly. I'll look at building something this weekend I think.
 
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