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cirrus10(at)qwest.net
Guest

Posted: Tue Aug 29, 2006 3:15 pm Post subject: wing spars

I am the second owner of a 6 in which the  previous owner did very little constructionwise, and am at the point of  attaching the wings.  One of wings fore spars has a bend on the vertical  (perpendicular to the shear of the insert).  It is a continuous bend from  end to end, and is 3/16" - 1/4" at the apex.  I carefully inspected  the rivets and glue joints on that spar and see nothing unusual.   

 Problem?  Do I need to replace the  spar?

  

 Thanks for any advice,

 Ed

   [quote][b]

donpearsall
Guest

Posted: Tue Aug 29, 2006 4:04 pm Post subject: wing spars

Ed, I am having trouble visualizing what you are  describing. Can you attach a photo of the part you are talking  about?

  

 Don



 [quote]         From: owner-kitfox-list-server(at)matronics.com    [mailto:owner-kitfox-list-server(at)matronics.com] On Behalf Of    cirrus10

Sent: Tuesday, August 29, 2006 4:14 PM

To:    kitfox-list(at)matronics.com

Subject: wing    spars

   

   I am the second owner of a 6 in which the    previous owner did very little constructionwise, and am at the point of    attaching the wings.  One of wings fore spars has a bend on the vertical    (perpendicular to the shear of the insert).  It is a continuous bend from    end to end, and is 3/16" - 1/4" at the apex.  I carefully inspected    the rivets and glue joints on that spar and see nothing unusual.     

   Problem?  Do I need to replace the    spar?

    

   Thanks for any advice,

   Ed

 	  Quote: 	
		  

	
[b]

ddsyverson(at)comcast.net
Guest

Posted: Tue Aug 29, 2006 4:24 pm Post subject: wing spars

Ed,



I am having a bit of difficulty visualizing where the damage is and what it 

looks like.



Any chance you have a digital photo?



Tubular spars depend on their strength from their shape.



Any bend will change the overall strength of the tube and will quite likely 

create a stress riser where a crack may start at some unknown time in the 

future. You may no longer be at design strength. It also makes a difference 

if it is in the middle of the spar, at the inboard attach point or on the 

last quarter inch on the outboard end.



Do you have the construction manual? What does it say about evaluating the 

condition of the spar tubes?



I threw away two spar tubes for my model 7 because I didn't like the scratches 

(Radial scratches - 0.003 - 0.005" deep) and got new ones.



I may be a bit more conservative than some.  I would be reluctant to advise 

anyone to incorporate a damaged spar tube in the wing.



Knowing what the actual strength is on a damaged spar, is a real experiment - 

too much of an experiment for me.



Sincerely,



Dave S

St Paul, MN



Do Not Archive 

On Tuesday 29 August 2006 6:14 pm, cirrus10 wrote:

 	  Quote: 	
		   I am the second owner of a 6 in which the previous owner did very little

 constructionwise, and am at the point of attaching the wings.  One of wings

 fore spars has a bend on the vertical (perpendicular to the shear of the

 insert).  It is a continuous bend from end to end, and is 3/16" - 1/4" at

 the apex.  I carefully inspected the rivets and glue joints on that spar

 and see nothing unusual. Problem?  Do I need to replace the spar?



 Thanks for any advice,

 Ed

rliebmann(at)comcast.net
Guest

Posted: Tue Aug 29, 2006 5:08 pm Post subject: wing spars

[quote]   Hi Ed,

   As I read your note, as you look down the spar    with the web vertical, the bend goes either to the right or left    depending.....is this correct?   

   Is the wing completely built?

   Send digital pics to the list if ya    can....

Ron   N55KF   



   I am the second owner of a 6 in which the    previous owner did very little constructionwise, and am at the point of    attaching the wings.  One of wings fore spars has a bend on the vertical    (perpendicular to the shear of the insert).  It is a continuous bend from    end to end, and is 3/16" - 1/4" at the apex.  I carefully inspected    the rivets and glue joints on that spar and see nothing unusual.     

   Problem?  Do I need to replace the    spar?

    

   Thanks for any advice,

   Ed

 	  Quote: 	
		  

	
[b]

cirrus10(at)qwest.net
Guest

Posted: Tue Aug 29, 2006 5:30 pm Post subject: wing spars

Thanks Dave,

There is really no damage per se.  It's more of a slight bow, no point along 

the spar can I say is the beginning or the end of the bow.  It's more like a 

cue stick that is bowed continuously from one end to the other.  The thing 

is, that it is bowed on the shear of the insert.



Regards,

Ed

---

cirrus10(at)qwest.net
Guest

Posted: Tue Aug 29, 2006 5:34 pm Post subject: wing spars

Actually, it's bowed on the shear of the insert, so  it is up and down.  The wing was factory built.  There is no actual  damage, but a slow bow from one end to the other.  

 What's the possibility of removing that spar with  heat?

  

 Regards,

 Ed

 [quote]   ---

Guy Buchanan

Joined: 16 Jul 2006
Posts: 1204
Location: Ramona, CA

Posted: Tue Aug 29, 2006 6:04 pm Post subject: wing spars

At 04:14 PM 8/29/2006, you wrote:

 	  Quote: 	
		  I am the second owner of a 6 in which the previous owner did very little 

constructionwise, and am at the point of attaching the wings.  One of 

wings fore spars has a bend on the vertical (perpendicular to the shear of 

the insert).  It is a continuous bend from end to end, and is 3/16" - 1/4" 

at the apex.  I carefully inspected the rivets and glue joints on that 

spar and see nothing unusual.

Problem?  Do I need to replace the spar?


	


Since you're at the point of attaching the wings that means they're 

assembled without strut fittings. It also means the bend must be vertical, 

(which you state,) since a horizontal bend would be evident in both spars. 

(The ribs should force the spars to be parallel, though it's certainly 

possible they were installed with a bow in the forward spar.) However, a 

vertical bend should be in the plane of the shear web of the insert, not 

perpendicular to it. The shear web should be a vertical "I" beam. Some 

clarification is required.



Given the bend is vertical, and about 3/16 - 1/4", you then have almost 1/2 

degree twist in the wing just due to the bend. If so, you may be able to 

trim the aircraft with the struts, but you're stall behavior will probably 

be less than desirable. Not to mention your aircraft will look like crap to 

the naked eye. (You'd be surprised how easy it is to see unnatural 

deformations.) I vote replace the spar. (I'd bend it back if the shear web 

weren't installed. There's too much of a risk of de-bonding the shear web 

with it installed.)

Guy Buchanan

K-IV 1200 / 582-C / Warp / 100% done, thanks mostly to Bob Ducar.

_________________
Guy Buchanan
Deceased K-IV 1200
A glider pilot too.

john(at)leptron.com
Guest

Posted: Tue Aug 29, 2006 6:07 pm Post subject: wing spars

Ed,  

1/4 “ does not seem like much, is the wing covered, and how is the wash out. if the wing is not covered you can take it out with the shrinking of the fabric. You could take the spar out with heat but it does not seem like much.  

   

John Oakley  

         

  

From: owner-kitfox-list-server(at)matronics.com [mailto:owner-kitfox-list-server(at)matronics.com] On Behalf Of cirrus10

 Sent: Tuesday, August 29, 2006 7:34 PM

 To: kitfox-list(at)matronics.com

 Subject: Re: wing spars  

  

     

Actually, it's bowed on the shear of the insert, so it is up and down.  The wing was factory built.  There is no actual damage, but a slow bow from one end to the other.    

    

What's the possibility of removing that spar with heat?  

    

   

    

Regards,  

    

Ed  

  [quote]    

---

john(at)leptron.com
Guest

Posted: Tue Aug 29, 2006 8:21 pm Post subject: wing spars

Ed,  

Is the leading edge on now? Removing and replacing this might fix the problem. Don’t panic yet, it does not seem bad.  

John Oakley  

         

  

From: owner-kitfox-list-server(at)matronics.com [mailto:owner-kitfox-list-server(at)matronics.com] On Behalf Of cirrus10

 Sent: Tuesday, August 29, 2006 7:34 PM

 To: kitfox-list(at)matronics.com

 Subject: Re: wing spars  

  

     

Actually, it's bowed on the shear of the insert, so it is up and down.  The wing was factory built.  There is no actual damage, but a slow bow from one end to the other.    

    

What's the possibility of removing that spar with heat?  

    

   

    

Regards,  

    

Ed  

  [quote]    

---

janderson412(at)hotmail.c
Guest

Posted: Tue Aug 29, 2006 11:42 pm Post subject: wing spars

If the wing is built, could it have been done on an wrongly set up jig?? And 

yes 1/4" over the full length doesn't seem much?? John A.





From: "John Oakley" <john(at)leptron.com>

Reply-To: kitfox-list(at)matronics.com

To: <kitfox-list(at)matronics.com>

Subject: RE: wing spars

Date: Tue, 29 Aug 2006 20:13:06 -0600

Ed,

1/4 “ does not seem like much, is the wing covered, and how is the wash out. 

if the wing is not covered you can take it out with the shrinking of the 

fabric. You could take the spar out with heat but it does not seem like 

much.



John Oakley





From: owner-kitfox-list-server(at)matronics.com 

[mailto:owner-kitfox-list-server(at)matronics.com] On Behalf Of cirrus10

Sent: Tuesday, August 29, 2006 7:34 PM

To: kitfox-list(at)matronics.com

Subject: Re: wing spars



Actually, it's bowed on the shear of the insert, so it is up and down.  The 

wing was factory built.  There is no actual damage, but a slow bow from one 

end to the other.

What's the possibility of removing that spar with heat?



Regards,

Ed

---

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Wed Aug 30, 2006 2:47 am Post subject: wing spars

Never heat structural  aluminium! .....  Not and use it again.

  

  

 

Noel [quote]   

   --

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

cirrus10(at)qwest.net
Guest

Posted: Wed Aug 30, 2006 5:03 am Post subject: wing spars

You're correct, parallel not perpendicular.

To remove the spar is the next question.  Would you suggest heating the tube 

and prying it away from the ribs?  Thanks.



Regards,

Ed

---

cirrus10(at)qwest.net
Guest

Posted: Wed Aug 30, 2006 5:08 am Post subject: wing spars

John,

 No, the leading edge is not on.  I,ll try some  clamping with the leading edge, and see if I can get some of the bow out.   Thanks.

  

 Regards,

 Ed

 [quote]   ---

cirrus10(at)qwest.net
Guest

Posted: Wed Aug 30, 2006 5:09 am Post subject: wing spars

The wing was factory built, aand yes that is a possibility.  Thanks.



Regards,

Ed

---

cirrus10(at)qwest.net
Guest

Posted: Wed Aug 30, 2006 5:10 am Post subject: wing spars

Noel,

 I meant for removal purposes, but that info is good  to know,.  Thanks.

  

 Regards,

 Ed

  

  

 [quote]   ---

john(at)leptron.com
Guest

Posted: Wed Aug 30, 2006 5:34 am Post subject: wing spars

Ed,  

Lay the wing upside down to help remove the bow. Place the leading edge in position, and then run continuous tape top and bottom of the leading edge.  

Sorry if I am pushy, I built several of these guys and learned a bunch. (ok, sometimes I think I am an expert) just slap me.  

John Oakley        

  

From: owner-kitfox-list-server(at)matronics.com [mailto:owner-kitfox-list-server(at)matronics.com] On Behalf Of cirrus10

 Sent: Wednesday, August 30, 2006 7:08 AM

 To: kitfox-list(at)matronics.com

 Subject: Re: wing spars  

  

     

John,  

    

No, the leading edge is not on.  I,ll try some clamping with the leading edge, and see if I can get some of the bow out.  Thanks.  

    

   

    

Regards,  

    

Ed  

  [quote]    

---

john(at)leptron.com
Guest

Posted: Wed Aug 30, 2006 6:06 am Post subject: wing spars

Ed,  

The stringers that hold the false ribs may hold the problem also, I assume they are in.  

   

John Oakley  

         

  

From: owner-kitfox-list-server(at)matronics.com [mailto:owner-kitfox-list-server(at)matronics.com] On Behalf Of John Oakley

 Sent: Wednesday, August 30, 2006 7:39 AM

 To: kitfox-list(at)matronics.com

 Subject: RE: wing spars  

  

   

Ed,  

Lay the wing upside down to help remove the bow. Place the leading edge in position, and then run continuous tape top and bottom of the leading edge.  

Sorry if I am pushy, I built several of these guys and learned a bunch. (ok, sometimes I think I am an expert) just slap me.  

John Oakley        

  

From: owner-kitfox-list-server(at)matronics.com [mailto:owner-kitfox-list-server(at)matronics.com] On Behalf Of cirrus10

 Sent: Wednesday, August 30, 2006 7:08 AM

 To: kitfox-list(at)matronics.com

 Subject: Re: wing spars  

  

     

John,  

    

No, the leading edge is not on.  I,ll try some clamping with the leading edge, and see if I can get some of the bow out.  Thanks.  

    

   

    

Regards,  

    

Ed  

  [quote]    

---

cirrus10(at)qwest.net
Guest

Posted: Wed Aug 30, 2006 6:40 am Post subject: wing spars

On the contrary John.  I'm not into  reinventing the wheel, and you're expertise is always appreciated.  The  stringer is installed on the top only.  Thanks again.

  

 Regards,

 Ed

 [quote]   ---

Guy Buchanan

Joined: 16 Jul 2006
Posts: 1204
Location: Ramona, CA

Posted: Wed Aug 30, 2006 6:55 am Post subject: wing spars

At 06:02 AM 8/30/2006, you wrote:

 	  Quote: 	
		  To remove the spar is the next question.  Would you suggest heating the tube

and prying it away from the ribs?


	


You don't really heat the tube, just the adhesive where the ribs bond. 

(Although if you're going to toss the tube you could just blow a torch down 

the middle, get the tube nice and hot, and then pull it off in one shot. Neat.)

Guy Buchanan

K-IV 1200 / 582-C / Warp / 100% done, thanks mostly to Bob Ducar.

_________________
Guy Buchanan
Deceased K-IV 1200
A glider pilot too.

john(at)leptron.com
Guest

Posted: Wed Aug 30, 2006 7:13 am Post subject: wing spars

Hi Ed,  

I think I have the whole picture now,   

The area with the insert is not bowed permanently because the insert is straight. So the problem was in jigging. The worse case scenario is taking off the upper stringer and rigging the wing to re install the stringers and leading edge. I have never seen a bent spar unless is damaged so no worry there. Both Dan and Phil were both very careful in their selection and inspection of materials. One more question, is the wood varnished?  

John Oakley  

         

  

From: owner-kitfox-list-server(at)matronics.com [mailto:owner-kitfox-list-server(at)matronics.com] On Behalf Of cirrus10

 Sent: Wednesday, August 30, 2006 8:40 AM

 To: kitfox-list(at)matronics.com

 Subject: Re: wing spars  

  

     

   

    

On the contrary John.  I'm not into reinventing the wheel, and you're expertise is always appreciated.  The stringer is installed on the top only.  Thanks again.  

    

   

    

Regards,  

    

Ed  

  [quote]    

---

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