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  #1  
Old 01-22-2017, 04:30 PM
warrenkm warrenkm is offline
 
Join Date: Nov 2014
Location: Nashville, TN
Posts: 5
Default Another HS00001 / SB 14-01-31 edge distance issue

Hello, long (long long) time lurker and new builder here (brand new emp kit too). Like many people I am having trouble with getting all the bits of the front spar lined up in such a way as to make sufficient edge distances on HS-00001. I won't divulge the quantity of "extra" 702s I have in my junk bin. Anyway, unless I drive HS-00001 all the way up to hit the flange and of course into the radius of HS702 I'm not going to make 2x diameter. When I look at SB 14-01-31 it mentions an edge distance requirement of only 1.25x (which I do make). Anyone notice this? Can someone explain the discrepancy between the usual edge distance criterion and what Van's is showing here?


Last edited by warrenkm : 01-22-2017 at 08:02 PM.
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  #2  
Old 01-23-2017, 06:50 AM
BillL BillL is offline
 
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Location: Central IL
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Since this is a stressed part, most are reluctant to make an off plan suggestion. Personally, I am not sure of the question. You might just get your specific question in order and call Vans about this. You can radius the edge to fit better in the inside radius. Just don't leave a sharp edge on it.

Here is a video of a retrofitted SB kit. Pretty good. It might give you some hints.
https://www.youtube.com/watch?v=HgE0T8EMaZk
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Old 01-23-2017, 10:12 AM
warrenkm warrenkm is offline
 
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Location: Nashville, TN
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Quote:
Originally Posted by BillL View Post
Since this is a stressed part, most are reluctant to make an off plan suggestion. Personally, I am not sure of the question. You might just get your specific question in order and call Vans about this. You can radius the edge to fit better in the inside radius. Just don't leave a sharp edge on it.

Here is a video of a retrofitted SB kit. Pretty good. It might give you some hints.
https://www.youtube.com/watch?v=HgE0T8EMaZk
Thanks for the response. To get straight to it - I am curious why the SB from Vans mentions an edge distance of 1.25X whereas it's traditionally 2X the rivet diameter. It's entirely possible I'm missing something very simple or misreading the text.

In my case I make the 1.25X (5/23" edge-to-edge distance in the above SB excerpt) but don't come close to 2x. If it ends up being an issue I'll roll my own HS00001 as I think no matter what I do with the factory part I'll end up with an edge distance problem somewhere.

I emailed Vans this morning so for posterity's sake I'll post the answer when I receive it.
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Old 01-23-2017, 10:55 AM
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Mach.26 Mach.26 is offline
 
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This is one of the worst designed parts in the empennage. I was nervous with the edge distance as well. I ended up going through 2 front spars and 2 doublers before I gave up and ordered some blank stock from ACS to fabricate my own doubler with slightly larger "ears" that I radiused to fit tightly in the flange radius. Perfect 1/4"+ edge distance now as measured from the center of the hold to edge of part.
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  #5  
Old 01-23-2017, 08:28 PM
warrenkm warrenkm is offline
 
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Location: Nashville, TN
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The response was:

"What you have looks to fall into the minimum allowable edge distance as determined by our engineers. From what I see in your pictures you can continue on whit what you have.

There are a number of builders that have done this over as you noticed but itís possible they were building this before our engineering team reevaluated the required edge distance. "

I don't know exactly what analysis they did but they found the reduced edge distance is okay. I ended up remaking the part and while I didn't get as much edge distance as I would've liked it's quite a bit more.
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Old 01-23-2017, 10:15 PM
Maxrate Maxrate is offline
 
Join Date: Dec 2008
Location: League city, TX
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I finally broke down and bought some .060 stock and made a slightly larger doubler per Vans suggestion and got the edge distance required. The YouTube video is great but good luck having it turn out that easy to get the repair done. I do however appreciate the guys that took the time to make the vid.
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  #7  
Old 01-23-2017, 10:32 PM
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jcarne jcarne is offline
 
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As I see it the minimum edge distance they specify in the SB seems to be fine. These planes were flying fine without the doubler, it was introduced to stop cracking. Also the SB mentions 5/32" center of rivet to edge; that only leaves 3/32" from edge of rivet (not a lot). It also mentions that if your edge distance is not in spec to go ahead and add one in between the rivets to address this. That's my 2 cents, hope it helps someone along the way make a decision.
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  #8  
Old 10-26-2017, 06:08 AM
Mlidzct Mlidzct is offline
 
Join Date: Nov 2016
Location: Southington, Ct
Posts: 40
Default Just had same problem

I just wasted some time with this as well. Just to clarify to future builders if you are building a new kit to plans you still need to look at the sb anyway because there is a lot more info in the sb than in the plans. The edge distance exception of 5/32 from Vans solves my problem. Also pay close attention to the fit between hs-00001 and the bend radius in hs-702. I put a radius on the edge and found that it was still digging in.

On another note I have an engineering backround and wondered why the rivet specs never consider material thickness in the edge distance equation. It doesnt make sense to me that .125 aluminum needs the same edge distance as .016. This is probably why vans allows a reduced edge distance on the .060 doubler.
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  #9  
Old 10-27-2017, 01:06 AM
keitht keitht is offline
 
Join Date: Jun 2016
Location: coupeville wa
Posts: 11
Default SB 14-01-31 issues

Did the SB and didn't like the result due to edge issues and not getting the doubler rivets equidistant about the rib attach rivet line and having the shop head interfere with the bend in the rib lip. (my bad)
Bought new forward spars, doublers and new ribs, disassembled the stabilizer and rebuilt with the new parts.
I took it slow and very carefully during the rebuild and spent a lot of time cross checking the design and manufacturing assembly process that Vans had documented. There is a lot that is not in the instructions or on the drawing so it made me feel better about the mistakes I made doing the SB. I am not surprised that a number of builders are having a problem with this SB. If I were doing it again I would drill out a number of skin rivets to provide better access to the forward spar and make it easier to perform the modification.
I decided to reattach the ribs using Cherrymax rivets due to not feeling very proficient with an offset rivet set in a tight location despite setting a dozen or so rivets in a tightly spaced test piece with the offset tool in the rivet gun. Certainly a skill that I need to worked on.
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  #10  
Old 10-27-2017, 08:48 AM
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az_gila az_gila is offline
 
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Exclamation Generic vs. specific

Quote:
Originally Posted by jcarne View Post
As I see it the minimum edge distance they specify in the SB seems to be fine. These planes were flying fine without the doubler, it was introduced to stop cracking. Also the SB mentions 5/32" center of rivet to edge; that only leaves 3/32" from edge of rivet (not a lot). It also mentions that if your edge distance is not in spec to go ahead and add one in between the rivets to address this. That's my 2 cents, hope it helps someone along the way make a decision.
Note that the 2D edge distance is only a generic guideline.

If the manufacturer/designer uses a different number, such as 1.25D, for a specific location, then that is the number to use.
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