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  #1  
Old 09-06-2020, 11:06 PM
jcarne's Avatar
jcarne jcarne is offline
 
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Location: Worland, Wyoming
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Question Is this flap to skin gap normal?

Posting this in general as it applies to more than a -7A.

If you look at the pics below you will notice a fairly good sized gap between the top wing skin and the flap. I would estimate the gap at about 1/8" when the flaps are retracted. The gap gets larger as the flaps are extended. Is anyone else out there flying with a gap like this? I understand Van's makes a loaner tool to fix this but I really don't want to go down this path if it doesn't gain me anything since my flaps are attached.

Just wanted to see if this is normal or not. Thanks for your input!

20200906_102134 by Jereme Carne, on Flickr

20200906_102120 by Jereme Carne, on Flickr
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Last edited by jcarne : 09-06-2020 at 11:08 PM.
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  #2  
Old 09-07-2020, 05:35 AM
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RV6_flyer RV6_flyer is offline
 
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Location: NC25
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Default

No.

Back in the days of the RV-4 and RV-6, the skin rubbed on the flap acting as a seal. That was the reason for the "stainless steel" tape and later the "plastic" tape was used to stop metal to metal contact / wear.
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  #3  
Old 09-07-2020, 05:53 AM
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rv8ch rv8ch is offline
 
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Default Mine has no gap

My top skin slides right on the flap, and I have some felt tape under the skin to keep from scratching the flap. Not sure that it is necessarily a bad thing, but best to check with the factory.
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  #4  
Old 09-07-2020, 06:43 AM
Desert Rat Desert Rat is offline
 
Join Date: Aug 2018
Location: Wichita KS
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Default

I had that same issue on my wings. At least on mine, the problem was that at the upper flange was underbent on the aft spar Z channel.

This was evidently a known issue at the factory for wing kits from a certain time frame (my wing kit was from around 2007) and they built a loaner tool to deal with it. Lots of threads about it if you just search "ski jump trailing edge"

I called Vans and was told the tool was out with another builder and they would put me on the lost for it, but I got tired of waiting and made my own.

It was annoying that I had to deal with it in the first place, but it worked out okay.

If your gap is caused by the same problem it will be easy to tell. Lay a straight edge along the wing chord-wise in that area. The last few inches should be flush. If theres a gap under the straight edge, then you've got the ski jump. If not, then I think you probably just need to bend the flap nose up to meet the wing.

There are pictures of this in my build log wing section from back in March
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  #5  
Old 09-07-2020, 06:46 PM
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Actually, that looks pretty good -- are they even?

My QB wings were circa 2015, and I had about 3/16" gap along the right flap and 1/8 - 3/16" along the left. Laying a straight edge along the various wing stations showed a "swale" along the aft spar flange, I guess the flange wasn't the right angle.

As mentioned elsewhere, the Van's "bend-o-matic" tool can shrink that down. However, I can report from first hand experience, after using this tool and taking the bend out, made absolutely 0 difference in top speed, Vs0 or Vs1, and left a little crease/mark along the spar flange location, fixed that with 320 grit paper.

So, you can make your own, or wait for the loaner, or leave it be...
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Last edited by bjdecker : 09-08-2020 at 03:40 PM. Reason: grammar
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  #6  
Old 09-07-2020, 08:26 PM
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jcarne jcarne is offline
 
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Default

Thanks for the replies everyone! I have addressed it with a bit of brute force and that seems to have worked really well. I spent many years working with sheet metal so stuff like this isn't totally new to me. Hard part is bending the flange of the spar and not the skin. Upon measuring the gap was a little less than 1/8". After my "treatment" the gap is about 1/32nd, perfect. See pic below.

Quote:
Originally Posted by bjdecker View Post
Actually, that looks pretty good -- are they even?

My QB wings were circa 2015, and I had about 3/16" gap along the right flap and 1/8 - 3/16" along the left. Laying a straight edge along the various wing stations showed a "swale" along along the aft spar flange, I guess the flange wasn't the right angle.

As mentioned elsewhere, the Van's "bend-o-matic" tool can shrink that down. However, I can report from first hand experience, after using this tool and taking the bend out, made absolutely 0 difference in top speed, Vs0 or Vs1, and left a little crease/mark along the spar flange location, fixed that with 320 grit paper.

So, you can make your own, or wait for the loaner, or leave it be...
Brian, thanks for posting, this is the kind of real world experience I was looking for! I suspected it wouldn't matter much but wanted to double check with those that have the experience.

P.S. I just learned a new word. haha
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  #7  
Old 09-07-2020, 08:28 PM
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jcarne jcarne is offline
 
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Here is the pic I promised.

20200907_155826 by Jereme Carne, on Flickr
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  #8  
Old 09-08-2020, 09:08 AM
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Raymo Raymo is offline
 
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The gap on mine is much larger. Having read bjdecker's post, I'm inclined to leave it alone.
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  #9  
Old 09-08-2020, 02:01 PM
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jcarne jcarne is offline
 
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Quote:
Originally Posted by Raymo View Post
The gap on mine is much larger. Having read bjdecker's post, I'm inclined to leave it alone.
Ya I would too. I only fixed mine because it was nagging me and at the time I didn't really want to straight edge my ailerons. haha Ended up doing it right after though lol
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