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Problems with top pre-drilled fuselage skin ( CH-701 )

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john.marzulli(at)gmail.co
Guest

Posted: Sun Sep 23, 2007 12:25 pm Post subject: Problems with top pre-drilled fuselage skin ( CH-701 )

I'm having a bit of a problem. The ("L") angle that attaches to the top of the baggage back is off by exactly 10mm. This seems strange since every other junction is dead on, and the longeron splices are exactly even between the sides and the top. The flanges for the bulkheads were dead on. 



So this leads me to believe it is a CNC error, but it's a little hard to get up there to measure and prove it.



Anyway, this has produced a gap too big to shim and I'm not sure what to do about it.  One thought I had was to move the angle forward, but then the existing holes would be directly over the baggage back and the vertical ("L") angles. 



My other idea was to ignore the gap basically since when I test fit the baggage back only the area near the gap didn't site flush. So I would add some extra rivets towards the inside of the panel to make up for it, and maybe add two gussets. My guess is that two rivets on each side would have to be skipped. 

Any thoughts?



I put pictures up on my blog: http://701Builder.blogspot.com/

Thanks!



-- 

John Marzulli

 http://701Builder.blogspot.com/



"Flying a plane is no different than riding a bicycle... it's just a lot harder to put baseball cards in the spokes.

-Airplane The Movie  [quote][b]

cscsail(at)gmavt.net
Guest

Posted: Sun Sep 23, 2007 1:11 pm Post subject: Problems with top pre-drilled fuselage skin ( CH-701 )

John,

 It looks like you could just reverse the L on  top.  

 Gordon 

  

 ---

NYTerminat(at)aol.com
Guest

Posted: Sun Sep 23, 2007 1:33 pm Post subject: Problems with top pre-drilled fuselage skin ( CH-701 )

In a message dated 9/23/2007 4:27:41 P.M. Eastern Daylight Time,  john.marzulli(at)gmail.com writes:

  	  Quote: 	
		  I'm    having a bit of a problem. The ("L") angle that attaches to the top of the    baggage back is off by exactly 10mm. This seems strange since every other    junction is dead on, and the longeron splices are exactly even between the    sides and the top. The flanges for the bulkheads were dead on.  

	


 

 Turn the top "L" around the other  way and it will fit.



Make AOL Your Homepage.

  [quote][b]

john.marzulli(at)gmail.co
Guest

Posted: Sun Sep 23, 2007 5:06 pm Post subject: Problems with top pre-drilled fuselage skin ( CH-701 )

The holes in the top skin are actually exactly where the flange needs to be, so flipping the ("L") angle would only move the flange from being 10mm too far aft to being 10mm too far forward.



And I'm pretty sure that the angle is in the right orientation. 



If the flange was in the wrong orientation, then wouldn't there be a 20mm discrepancy?



Thanks,



-John



On 9/23/07,  NYTerminat(at)aol.com (NYTerminat(at)aol.com) <NYTerminat(at)aol.com (NYTerminat(at)aol.com)> wrote:[quote]       In a message dated 9/23/2007 4:27:41 P.M. Eastern Daylight Time,  john.marzulli(at)gmail.com (john.marzulli(at)gmail.com) writes:

  	  Quote: 	
		  I'm    having a bit of a problem. The ("L") angle that attaches to the top of the    baggage back is off by exactly 10mm. This seems strange since every other    junction is dead on, and the longeron splices are exactly even between the    sides and the top. The flanges for the bulkheads were dead on.  

	


 

 Turn the top "L" around the other  way and it will fit.



 Make AOL Your Homepage.

  [quote][b]  http://www.matronics.com/Navigator?Zenith-List http://forums.matronics.com 



"Flying a plane is no different than riding a bicycle... it's just a lot harder to put baseball cards in the spokes.

-Airplane The Movie  [quote][b]

NYTerminat(at)aol.com
Guest

Posted: Sun Sep 23, 2007 5:51 pm Post subject: Problems with top pre-drilled fuselage skin ( CH-701 )

John,

  

 Looking at my drawings, 01/04,  7-F-3 shows  the dimensions of the centers of the L angles. How does that compare to your CNC  holes? Also on my plane the holes for the side skin and top skin at the  upper longeron are lined up, I think yours are offset by 10 mm. This may be  the base of the problem.

  

 Bob Spudis

  

  

  

  

 In a message dated 9/23/2007 9:07:24 P.M. Eastern Daylight Time,  john.marzulli(at)gmail.com writes:

  	  Quote: 	
		  The    holes in the top skin are actually exactly where the flange needs to be, so    flipping the ("L") angle would only move the flange from being 10mm too far    aft to being 10mm too far forward.



And I'm pretty sure that the angle    is in the right orientation. 



If the flange was in the wrong    orientation, then wouldn't there be a 20mm    discrepancy?



Thanks,



-John



   On 9/23/07, NYTerminat(at)aol.com (NYTerminat(at)aol.com) <NYTerminat(at)aol.com (NYTerminat(at)aol.com)> wrote:     	  Quote: 	
		                 In a message dated 9/23/2007 4:27:41 P.M. Eastern Daylight Time, john.marzulli(at)gmail.com (john.marzulli(at)gmail.com) writes:

      	  Quote: 	
		  I'm having        a bit of a problem. The ("L") angle that attaches to the top of the        baggage back is off by exactly 10mm. This seems strange since every other        junction is dead on, and the longeron splices are exactly even between the        sides and the top. The flanges for the bulkheads were dead on.      

	


     

     Turn the top "L" around the other way and it will      fit.



               Make AOL Your Homepage.

 	  Quote: 	
		  



http://www.matronics.com/Navigator?Zenith-List

http://forums.matronics.com

"Flying a plane is no different than riding a bicycle... it's just a lot harder to put baseball cards in the spokes.-Airplane The Movie



 	  Quote: 	
		  [b]



f="http://www.matronics.com/Navigator?Zenith-List">http://www.matronics.com/Navigator?Zenith-List

.matronics.com/">http://forums.matronics.com



	
[/b] 	


	


	


 

  



See what's new="_blank">Make AOL Your Homepage.

  [quote][b]

ProWash

Joined: 26 Apr 2007
Posts: 18

Posted: Sun Sep 23, 2007 6:01 pm Post subject: Re: Problems with top pre-drilled fuselage skin ( CH-701 )

I just went through the same situation two weeks ago.  I drilled out the rivets and installed a new "L" 5mm farther forward, through the same holes.  This left a gap of only 5mm.  The rivets are very close to the flange, but I don't see it as a problem.  The baggage back wall flexed enough to work out well.



I spoke to Roger at Zenith about it.  He said he would look into it.

_________________
R Craig
North Central Arkansas
N701LR CH701 SP ELB
30 HRS into Phase One testing
Do Not Archive

txpilot

Joined: 26 Feb 2007
Posts: 87
Location: Houston, TX

Posted: Mon Sep 24, 2007 6:45 am Post subject: Re: Problems with top pre-drilled fuselage skin ( CH-701 )

John,



I had similar problems when I built my rear fuselage.  Here's what I suggest as a solution:



Talk to Roger at ZAC and order new 'L' brackets with one flange at 20mm (normal) and the other flange at 30mm.  Use these extended flange 'L' brackets on the side skins.  Remove your current side 'L' brackets, clamp the small flange to the top and bottom 'L' bracket flanges, and drill through your existing side skin holes into the new "long" flange.  Yes, it will be slightly off vertical if your bottom and top 'L' brackets are not plumb, but it seems from your picture that it won't be too far off.  It will guarantee the 'L' bracket flanges will be flush with each other with no gap.



BTW - on your website, you mentioned placing diagonal 'L' brackets on your skin to reduce oil canning noise.  I did the same on mine.  I'm not flying yet, so I don't know if it really helps.  However, you'll notice ZAC has these 'L' brackets on their aircraft model.  Guess it can't be a bad idea.



Best Regards,



Dan Ginty

john.marzulli(at)gmail.co
Guest

Posted: Mon Sep 24, 2007 7:37 am Post subject: Problems with top pre-drilled fuselage skin ( CH-701 )

Thanks for the advice!



On 9/24/07, txpilot <djg7(at)comcast.net (djg7(at)comcast.net)> wrote:[quote] --> Zenith-List message posted by: "txpilot" <djg7(at)comcast.net (djg7(at)comcast.net)>



John,



I had similar problems when I built my rear fuselage.  Here's what I suggest as a solution: 



Talk to Roger at ZAC and order new 'L' brackets with one flange at 20mm (normal) and the other flange at 30mm.  Use these extended flange 'L' brackets on the side skins.  Remove your current side 'L' brackets, clamp the small flange to the top and bottom 'L' bracket flanges, and drill through your existing side skin holes into the new "long" flange.  Yes, it will be slightly off vertical if your bottom and top 'L' brackets are not plumb, but it seems from your picture that it won't be too far off.  It will guarantee the 'L' bracket flanges will be flush with each other with no gap. 



BTW - on your website, you mentioned placing diagonal 'L' brackets on your skin to reduce oil canning noise.  I did the same on mine.  I'm not flying yet, so I don't know if it really helps.  However, you'll notice ZAC has these 'L' brackets on their aircraft model.  Guess it can't be a bad idea. 



Best Regards,



Dan Ginty





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=136095#136095 http://701Builder.blogspot.com/



"Flying a plane is no different than riding a bicycle... it's just a lot harder to put baseball cards in the spokes.

-Airplane The Movie  [quote][b]

john.marzulli(at)gmail.co
Guest

Posted: Mon Sep 24, 2007 9:46 am Post subject: Problems with top pre-drilled fuselage skin ( CH-701 )

First, I want to thank everyone who provided a response, on and off list.



I talked to Roger at Zenith today and we came up with two possible solutions.



The first is to see if the angles can be bent to match. Since there are so many rivets in the baggage back, structural integrity should not be an issue. 



If I can't get that to work, then Roger offered to send out a new skin with the offending rivet line not drilled.



Due to the fact that I have the fuselage squared up with the longerons matching I want to avoid using a new skin even if the holes theoretically match simply because they may not. 



Once again thanks for all the help!



-John in Seattle



On 9/23/07, John Marzulli <john.marzulli(at)gmail.com  (john.marzulli(at)gmail.com)> wrote: 	  Quote: 	
		  I'm having a bit of a problem. The ("L") angle that attaches to the top of the baggage back is off by exactly 10mm. This seems strange since every other junction is dead on, and the longeron splices are exactly even between the sides and the top. The flanges for the bulkheads were dead on. 



So this leads me to believe it is a CNC error, but it's a little hard to get up there to measure and prove it.



Anyway, this has produced a gap too big to shim and I'm not sure what to do about it.  One thought I had was to move the angle forward, but then the existing holes would be directly over the baggage back and the vertical ("L") angles. 



My other idea was to ignore the gap basically since when I test fit the baggage back only the area near the gap didn't site flush. So I would add some extra rivets towards the inside of the panel to make up for it, and maybe add two gussets. My guess is that two rivets on each side would have to be skipped. 

Any thoughts?



I put pictures up on my blog: http://701Builder.blogspot.com/ 

Thanks!



-- 

John Marzulli

 http://701Builder.blogspot.com/



"Flying a plane is no different than riding a bicycle... it's just a lot harder to put baseball cards in the spokes.

-Airplane The Movie 	


-- 

John Marzulli

http://701Builder.blogspot.com/



"Flying a plane is no different than riding a bicycle... it's just a lot harder to put baseball cards in the spokes. 

-Airplane The Movie  [quote][b]

ashontz

Joined: 27 Dec 2006
Posts: 723

Posted: Tue Sep 25, 2007 6:32 am Post subject: Re: Problems with top pre-drilled fuselage skin ( CH-701 )

For stuff like this it's worth building the Zenith 48 inch bending brake.



 	  txpilot wrote: 	
		  John,



I had similar problems when I built my rear fuselage.  Here's what I suggest as a solution:



Talk to Roger at ZAC and order new 'L' brackets with one flange at 20mm (normal) and the other flange at 30mm.  Use these extended flange 'L' brackets on the side skins.  Remove your current side 'L' brackets, clamp the small flange to the top and bottom 'L' bracket flanges, and drill through your existing side skin holes into the new "long" flange.  Yes, it will be slightly off vertical if your bottom and top 'L' brackets are not plumb, but it seems from your picture that it won't be too far off.  It will guarantee the 'L' bracket flanges will be flush with each other with no gap.



BTW - on your website, you mentioned placing diagonal 'L' brackets on your skin to reduce oil canning noise.  I did the same on mine.  I'm not flying yet, so I don't know if it really helps.  However, you'll notice ZAC has these 'L' brackets on their aircraft model.  Guess it can't be a bad idea.



Best Regards,



Dan Ginty

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