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XL Wing Attachment Modification

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japhillipsga(at)aol.com
Guest

Posted: Thu May 01, 2008 12:02 pm Post subject: XL Wing Attachment Modification

 	  Quote: 	
		  XL Friends, Flyers and Builders, I'm considering modifying the wing attachments for my XL. I just finished attaching the wings to my RV-8a and the difference is considerable. Beefed up rear spar 

attachment clamp and a forward attachment point at the wing tip. Any of you fellows that know RVs

understand the difference in attachment physically. Sure would reduce the wing twising concern

that may have contributed to various crashes. Anybody have any constructive, pro-active thoughts

on the issue? 

Best regards, Bill of Georgia

601XL-3300 130 hrs 

Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=180530#180530





	


 Plan your next roadtrip with MapQuest.com: America's #1 Mapping Site. 

  [quote][b]

Tim Juhl

Joined: 21 Mar 2006
Posts: 488
Location: "Thumb" of Michigan

Posted: Thu May 01, 2008 12:35 pm Post subject: Re: XL Wing Attachment Modification

I've often wondered about the strength of the rear spar attachment.  With all the people stepping back there to board the plane it has to support more than just flight loads. It is critical to maintaining the XL's wing geometry even if the main spar carries the bulk of the load.  That said, I would be reluctant to make a major modification to the design without ZAC's blessing.



May I ask what you meant in your post where you said: "forward attachment point at the wing tip"



Tim



do not archive

_________________
______________
CFII
Champ L16A flying
Zodiac XL - Jabiru 3300A
Almost done! It'll fly in spring!

m.l.marcotte(at)sympatico
Guest

Posted: Thu May 01, 2008 1:18 pm Post subject: XL Wing Attachment Modification

I would look for sources of  flutter before tampering with the basic structure.  I mean like this  one from Joe about the trim tab: 

 



"Use bolts to attach the horn, not rivets.  

The fasteners are loaded in tension. 

Mine  became loose in fewer than 100 hours. 



Joe E  

N633Z (at) BFI 

332 hours  

CH601XL, Jabiru 3300, Sensenich 64x49 

On Sun,  7 May 2006"

  

  

 Doesn't this look like a smoking  gun?

  

 [quote]   ---

PatrickW

Joined: 27 Oct 2006
Posts: 380
Location: Fort Worth, Texas

Posted: Thu May 01, 2008 2:03 pm Post subject: Re: XL Wing Attachment Modification

 	  Quote: 	
		  I just finished attaching the wings to my RV-8a and the difference is considerable. 	




If I'm not mistaken, didn't the RV-8 owned by Mr VanG himself shed it's wings, taking two of his friends...?



Does anyone know any more about that, and if so, was there any changes made to the airframe after that?



Patrick

XL/Corvair

N63PZ (reserved)

cndmovn(at)gmail.com
Guest

Posted: Thu May 01, 2008 4:15 pm Post subject: XL Wing Attachment Modification

"I am working on an airbus 380 and I looked at the zenith spar attachment".....it is like comparing apples to oranges!  One designer might have added thickness to a structure while another added physical attachments.   This list had degenerated into a bunch of people raising issues and fears that can never be answered.  You might as well ask...If I put an underweight elephant in the right seat of the airplane, would adding another AN4 bold make it safe?

 

There are few if no qualified people on this list to answer this question.  There are a LOT of people on this list who will give you an answer who have NO idea what they are talking about.



Bottom line....if you don't like the design or trust the designer, sell the project and move onto something else.  

 

BTW, before I get cat call for being insensitive, I AM NOT making fun of you.....just the rest of the so call engineers on this list who while give you "solutions"





Paul



 On Thu, May 1, 2008 at 6:15 PM, M.Marcotte <m.l.marcotte(at)sympatico.ca (m.l.marcotte(at)sympatico.ca)> wrote:

[quote]        I would look for sources of  flutter before tampering with the basic structure.  I mean like this  one from Joe about the trim tab: 

 



"Use bolts to attach the horn, not rivets.  

The fasteners are loaded in tension. 

Mine  became loose in fewer than 100 hours. 



Joe E  

N633Z (at) BFI 

332 hours  

CH601XL, Jabiru 3300, Sensenich 64x49 

On Sun,  7 May 2006"

  

  

 Doesn't this look like a smoking  gun?

  

 [quote]   ---

Afterfxllc(at)aol.com
Guest

Posted: Thu May 01, 2008 4:35 pm Post subject: XL Wing Attachment Modification

 	  Quote: 	
		  I agree    100% Last night i made a post and inverted trailing edge for leading edge with    regards to the vans aileron but most on this and every other list just like to    kick ideas around and will never do what they propose and I for 1 will not    deviate from the plans and if I have to deviate because of something beyond my    control I always call Zenith for guidance. I agree that unless someone wants    to pay big bucks for wind tunnel tests and tests till destruction    of control surfaces then all this is merely chatter and nothing    more. Take it for what it's worth. 	
  

 Jeff

  

  

  

  	  Quote: 	
		  "I am    working on an airbus 380 and I looked at the zenith spar attachment".....it is    like comparing apples to oranges!  One designer might have added    thickness to a structure while another added physical attachments. �    This list had degenerated into a bunch of people raising issues and fears that    can never be answered.  You might as well ask...If I put an underweight    elephant in the right seat of the airplane, would adding another AN4 bold make    it safe?



There are few if no qualified people on this list to answer    this question.  There are a LOT of people on this list who will give you    an answer who have NO idea what they are talking about.



Bottom    line....if you don't like the design or trust the designer, sell the project    and move onto something else.  



BTW, before I get cat call for    being insensitive, I AM NOT making fun of you.....just the rest of the so call    engineers on this list who while give you    "solutions"





Paul



   On Thu, May 1, 2008 at 6:15 PM, M.Marcotte <m.l.marcotte(at)sympatico.ca (m.l.marcotte(at)sympatico.ca)>    wrote:

    	  Quote: 	
		            I would look for sources of      flutter before tampering with the basic structure.  I mean like      this one from Joe about the trim tab: 

     



"Use bolts to attach the horn, not rivets.      

The fasteners are loaded in tension. 

Mine      became loose in fewer than 100 hours. 



Joe E      

N633Z (at) BFI 

332 hours      

CH601XL, Jabiru 3300, Sensenich 64x49 

On      Sun, 7 May 2006"

      

      

     Doesn't this look like a smoking      gun?

      

      	  Quote: 	
		                -----        Original Message ----- 

       From:        japhillipsga(at)aol.com (japhillipsga(at)aol.com) 

       To:        zenith-list(at)matronics.com (zenith-list(at)matronics.com) 

       Sent:        Thursday, May 01, 2008 2:58 PM

       Subject:        XL Wing Attachment Modification 

       





        	  Quote: 	
		  XL Friends, Flyers and Builders, I'm considering modifying the wing attachments for my XL. I just finished attaching the wings to my RV-8a and the difference is considerable. Beefed up rear spar 



attachment clamp and a forward attachment point at the wing tip. Any of you fellows that know RVs

understand the difference in attachment physically. Sure would reduce the wing twising concern

that may have contributed to various crashes. Anybody have any constructive, pro-active thoughts

on the issue? 

Best regards, Bill of Georgia

601XL-3300 130 hrs 



Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=180530#180530



	




	


	


	
 

  



Wondering what's for Dinner Tonight? Get new twists on family favorites at AOL Food.

  [quote][b]

frankroskind(at)HOTMAIL.C
Guest

Posted: Thu May 01, 2008 7:03 pm Post subject: XL Wing Attachment Modification

We don't know the causes of the accidents, nor may we ever know.  We know that one symptom of the failure was a failure of the wing spar, but we do not understand the causative mechanism.  I have read thousands of accident reports from many modes of transportation, and the only thing I would say is consistent is the fog that remains after a good investigation.� We know that some failures were part of the causal chain of some accidents, and that the accidents would likely not have happened had the failure not happened, or if there had been coverage for the failure, but in the end there is a lot of educated, in some cases very highly educated, speculation.  I am not an engineer, but I do have duties which require me to find common factors in accidents.  In this case the apparent common factor is the wing failure.  We know almost nothing about the serviced history previous to the flights.  It is very possible that a crack initiated days, weeks, months, or even years before the accidents.  The accidents may have involved a unique alignment of circumstances that has not occurred, and probably will not occur, to potential analysts.  It may be that crosswind landings on turf fields in cold weather during the dark of the moon affects holes reamed and then polished with the wrong color of scotchbrite pad, but only in aircraft flown by left-handed, right-eyed pilots flying from the left seat.  Aside from the phase of the moon, it is possible that any of these factors might have influenced the likelihood of a wing failure, and there are thousands of other, similarly inoccuous sounding conditions that might actuallly have had an effect.  OTOH, strenghteneing an attachment point without engineering support increases the likelihood that you will transfer forces to a different point on the airplane, which is not designed to handle the additional load.  Mr. Heintz is generous enough to lend engineering support to builders who ask for it, so I believe that you are foolhardy if you are not a qualifed engineer, and also decline to run your proposed changes by the designer.

  	  Quote: 	
		    To: zenith-list(at)matronics.com

Subject: XL Wing Attachment Modification 

Date: Thu, 1 May 2008 15:58:54 -0400

From: japhillipsga(at)aol.com

  	  Quote: 	
		  XL Friends, Flyers and Builders, I'm considering modifying the wing attachments for my XL. I just finished attaching the wings to my RV-8a and the difference is considerable. Beefed up rear spar 

attachment clamp and a forward attachment point at the wing tip. Any of you fellows that know RVs

understand the difference in attachment physically. Sure would reduce the wing twising concern

that may have contributed to various crashes. Anybody have any constructive, pro-active thoughts

on the issue? 

Best regards, Bill of Georgia

601XL-3300 130 hrs 

Read this topic online here:

http://forums.matronics.com/viewtopic.php?p=180530#180530

   Plan your next roadtrip with MapQuest.com: America's #1 Mapping Site. 

 	  Quote: 	

arget=_blank>http://www.matronics.com/Navigator?Zenith-List

p://forums.matronics.com

blank>http://www.matronics.com/contribution

Make i'm yours. Create a custom banner to support your cause.  [quote][b]

Afterfxllc(at)aol.com
Guest

Posted: Thu May 01, 2008 9:03 pm Post subject: XL Wing Attachment Modification

The wing of the Van's RV attaches to the leading edge fuel tank  inboard rib not the rear spar like the 601. The fuel tank is removable and when  you remove it you also unbolt the attach point for the wing. But the  spar is deeper in the wing also.

  

 Jeff

  	  Quote: 	
		  May I    ask what you meant in your post where you said: "forward attachment point at    the wing tip" 	


 

  



Wondering what's for Dinner Tonight? Get new twists on family favorites at AOL Food.

  [quote][b]

amyvega2005(at)earthlink.
Guest

Posted: Fri May 02, 2008 5:45 am Post subject: XL Wing Attachment Modification

I was told the following by an RV 8 pilot " plane did a Snap role above its permited weight,  wings were stressed outboard,  then the after a few flights, the wing snapped."



Juan



--

japhillipsga(at)aol.com
Guest

Posted: Fri May 02, 2008 10:17 am Post subject: XL Wing Attachment Modification

Tim, on the RV wing, at least on the 8 & 9 that I have worked on and built, the forward end of the nose skin has a .125 "L" bracket riveted to the wing rib (wet tanks). Then a corsponding "L" bracket is bolted to the side of the fuselage. There is considerable doubler metal in the surrounding area providing great strength to the fuselage bracket. These two brackets are overlapped and a 5/8 bolt connects. Talking with other builders I have heard that the forward attachment complements the drag spar attachment in combating wing twist and that when the fuel tanks are full they illeminate wing droop and metal stretch from occurring. On the XL some doublers would have to be added and some nose skin would have to be removed for attachment (or maybe a plug hole?, but such modification would not be too difficult. Best Regards, Bill 

 

 

 --

japhillipsga(at)aol.com
Guest

Posted: Fri May 02, 2008 10:34 am Post subject: XL Wing Attachment Modification

Paul, I for one appreciate your enlightened response. As I have completed my XL some years back it is really no longer a project, but rather an airplane I fly regularly and depend upon not to kill me and my Grandchildren. I retain only a margin of trust in any object I own and always consider that it (or anything) may have design and material flaws or errors. It would be less than prudent to blindly trust anyone's opinion other than yourself. Never the less, opinion of even the least informed may be of some merit and I hope anyone with an idea will respond. Again, thank you for taking the time to offer your sensitive opinion on the subject and I certainly don't believe your making fun of me. Best regards, Bill

 do not archive. 

 

 

 --

japhillipsga(at)aol.com
Guest

Posted: Fri May 02, 2008 10:54 am Post subject: XL Wing Attachment Modification

Frank, I certainly agree with you and I appreciate your opinion. I will either make such mods or I will not. Never the less, I decided to seek opinions from us builders about possible merit before bouncing the issue with ZAC. I suspect they are pretty sensitive to the issue and concerns by now. Something had to come first. Best regards, Bill

 

 

 --

japhillipsga(at)aol.com
Guest

Posted: Fri May 02, 2008 11:01 am Post subject: XL Wing Attachment Modification

Jeff, I think you may have over looked the fact that the RV wing does attach at the rear spar as well. I drilled and reamed and bolted mine last month. The RV rear spear attachment is bolted for shear, but also has three layers of metal lapping that actually are clamped together by the bolt. Look again, Best regards, Bill

 do not archive

 

 --

jshep00(at)centurytel.net
Guest

Posted: Fri May 02, 2008 6:03 pm Post subject: XL Wing Attachment Modification

I'm with you Frank, probably the wrong color of  scotchbrite.   That being said, I for one will add some of the  11# saved by using the Grove Landing gear instead of the ZAC one to the wing  attachment area, both wing and center spar.  This is an experimental  aircraft!!!  If this causes something else to become the weakest link,  so be it, My mods will most likeky be about 3-4 Sq feet of 1/4" 6061 T6 placed  between the spar caps, 50 solid rivets and 12 more bolts. About 6#.    I will leave the current attachment points as they are. I probably  will run it by ZAC, however, my past experience has been less than exciting in  doing so.  I guess everyone needs to seek their own level of experimental  security. My 701 definately is Experimental with about 100+# too much  firewall forward, 30 ft wingspan and VG's.

 Everyone who wonders how Chris handles similar things  should go to the 701 site and look at the rear spar attachment channel  modification.

 [quote]   ---

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