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Rib Stitching

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Richard Pike

Joined: 09 Jan 2006
Posts: 1671
Location: Blountville, Tennessee

Posted: Tue Jul 20, 2010 6:26 pm Post subject: Rib Stitching

Had a friend come over today and help me with the covering. Occurred to me that maybe some Kolbers had never done or seen any rib stitching, so we filmed it. 

This is doing the false ribs:

http://www.youtube.com/watch?v=estp-yxb0XA



This is doing the normal ribs:

http://www.youtube.com/watch?v=uJjuljzCpbI



Richard Pike

MKIII N420P (420ldPoops)

slyck(at)frontiernet.net
Guest

Posted: Tue Jul 20, 2010 6:58 pm Post subject: Rib Stitching

Very well done Richard.  The advantages are:  doesn't weaken the rib as much as drilling and riveting

and if you need to recover you don't have to drill 'em out.

-besides, it looks neat.

BB



On 20, Jul 2010, at 10:26 PM, Richard Pike wrote:



 	  Quote: 	
		   

 

 Had a friend come over today and help me with the covering. Occurred to me that maybe some Kolbers had never done or seen any rib stitching, so we filmed it. 

 This is doing the false ribs:

 http://www.youtube.com/watch?v=estp-yxb0XA

 

 This is doing the normal ribs:

 http://www.youtube.com/watch?v=uJjuljzCpbI

 

 

 

 Richard Pike

 MKIII N420P (420ldPoops)

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=305684#305684

Eugene Zimmerman

Joined: 10 Jan 2006
Posts: 392

Posted: Wed Jul 21, 2010 4:09 am Post subject: Rib Stitching

Bob,

But is it actually stronger?

The stitch would surely tear/wear through the fabric before a rivet  

would pull through the reinforcing tape and fabric?



Gene

On Jul 20, 2010, at 10:57 PM, robert bean wrote:



 	  Quote: 	
		   Very well done Richard.  The advantages are:  doesn't weaken the rib  

 as much as drilling and riveting

 and if you need to recover you don't have to drill 'em out.

 -besides, it looks neat.

 BB

slyck(at)frontiernet.net
Guest

Posted: Wed Jul 21, 2010 4:59 am Post subject: Rib Stitching

In a certified aircraft you lay(glue) reinforcing tape on before the rib stitching.  I would do a Kolb the same way.

My Aeronca used little stainless screws into aluminum ribs, also through reinforcing tape.

I got in a lovely 8:00 PM flight last night.  77F and calm.  Wonderfully tranquil and smooth.

Don't get many of those.

BB

On 21, Jul 2010, at 8:09 AM, Eugene Zimmerman wrote:

 	  Quote: 	

 Bob,

 But is it actually stronger?

 The stitch would surely tear/wear through the fabric before a rivet would pull through the reinforcing tape and fabric?

 Gene

 On Jul 20, 2010, at 10:57 PM, robert bean wrote:

> Very well done Richard.  The advantages are:  doesn't weaken the rib as much as drilling and riveting

> and if you need to recover you don't have to drill 'em out.

> -besides, it looks neat.

> BB

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Wed Jul 21, 2010 6:35 am Post subject: Rib Stitching

> But is it actually stronger?

 	  Quote: 	
		   The stitch would surely tear/wear through the fabric before a rivet  would 

 pull through the reinforcing tape and fabric?



 Gene


	




Rib stitching was used for flat wooden rib strips which gave the stitch more 

area and a flat surface to attach the fabric.



Normally, sheet metal ribs use clips or screws.



Fabric rivets work well with tubing, especially small, 5/16" tubing.



Rib stitching does not grip small diameter, smooth tubing as well as it does 

flat wooden strips.



Tube ribs, 5/16", have a very small apex that makes contact with the fabric. 

I noticed Richard P made his stits as wide as the reinforcing tape.  Seems 

to me this would pull a pucker in the fabric as the knot was tightened.  I 

could not tell from the vid clip.



john h

mkIII

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

Richard Pike

Joined: 09 Jan 2006
Posts: 1671
Location: Blountville, Tennessee

Posted: Wed Jul 21, 2010 8:39 am Post subject: Re: Rib Stitching

Wow, good responses, thanks guys!

To reply to Eugene's question, if you did not use reinforcing tape, the cord would cut through the fabric so quickly you would not even be able to do it, so whether you are using cord or rivets, you have to use reinforcing tape below the cord or rivet in either case. Then whether you are using a rivet or a cord passing over it, one is going to be as strong as another. The cord method has a long history of not failing, and at the speeds we fly, it is surely not an issue. 



In reply to John's comment that rib stitching does not grip small diameter, smooth tubing as well as it does flat wooden strips, I guess we will have to agree to disagree. If you have a length of reinforcing tape laying along the top of the rib, and a cord wraps around that rib, then the cord is pulling on the tape across the full width of the tape. A rivet flat across the top of the tape is touching more of the tape, but less of the rib, except that is not an issue, because of the mechanical assistance of the finishing tape over the whole bit, which is what is actually holding everything together.



As far as 5/16" tube ribs having a very small apex that makes contact with the fabric, that is the case whether you are using rivets or cord. The fabric is held securely by the finishing tape that you lay over the top of the whole business after your mechanical attachment is complete. If you did not put the finishing tape over everything else, I doubt that either method would be very secure. 



Also, you do not get a pucker in the fabric if you use the right size reinforcing tape. I used Stits 1/4" wide reinforcing tape, and when the cord is tightened, it pulls down perfectly with no pucker. If you used wider reinforcing tape, then obviously you would have a mess.



We had to use rivets at the tip rib, since the reinforcing angle right next to the rib precluded rib stitching, also we riveted a couple places above and below the main spar since there is no way to get a needle around it, and it wasn't worth the trouble to get fancy and make a custom needle. 



Here are pictures comparing two adjacent ribs, one the riveted tip rib, and one stitched, the finishing tape has not yet been ironed. Judge for yourself which one creates more of a pucker, bump or whatever.



Stitching the full ribs is fairly time effective, because you are effectively doing two rivets with one full stitch, doing false ribs is certainly not. Rivets would have to be quicker, except I hate drilling all those holes in my ribs, and invariably I screw a couple up, and I hate that. To each his/her own, all this is for is to shed a little light on the process for those who might want to try the alternative.



Richard Pike

MKIII N420P (420ldPoops)

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williamtsullivan(at)att.n
Guest

Posted: Wed Jul 21, 2010 8:53 am Post subject: Rib Stitching

My two cents worth. I had two sets of wings for the Firestar, one original set that was damaged in a storm rollover, and the other set was damaged when I crashed it.  One set was rib stitched, and the other was riveted.  Even though both of them had extensive structural damage, neither one had any sign of attachment failure.  When I rebuilt the wings, I used rivets because of extensive experience and familiarity with them.  If I do another set, ecpecially a very lightweight set, I probably will use stitching twine to cross brace the ribs.  That way there will be less warping when the fabric is tightened.  

  

                                                Bill Sullivan

                                                Windsor Locks, Ct.

                                                5 rib FS 447

 [quote][b]

Eugene Zimmerman

Joined: 10 Jan 2006
Posts: 392

Posted: Wed Jul 21, 2010 5:59 pm Post subject: Rib Stitching

Richard,



Thanks  for that clarification. In the video I missed seeing the  

reinforcing tape as you were doing the stitching.  Either your  

workmanship is exceptional, or my eyes are not.  Apparently it is the  

former.  My confidence in you as a Kolb builder is restored.   <grin>



Gene Z



On Jul 21, 2010, at 12:39 PM, Richard Pike wrote:



 	  Quote: 	
		   Wow, good responses, thanks guys!

 To reply to Eugene's question, if you did not use reinforcing tape,  

 the cord would cut through the fabric so quickly you would not even  

 be able to do it, so whether you are using cord or rivets, you have  

 to use reinforcing tape below the cord or rivet in either case. Then  

 whether you are using a rivet or a cord passing over it, one is  

 going to be as strong as another. The cord method has a long history  

 of not failing, and at the speeds we fly, it is surely not an issue

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Wed Jul 21, 2010 7:44 pm Post subject: Rib Stitching

Then

 	  Quote: 	
		  > whether you are using a rivet or a cord passing over it, one is  going to 

> be as strong as another.


	


Maybe if both systems are using the same width reinforcing tape.  However, I 

believe 1/4" reinforcing tape will not be as strong as 1/2".



 	  Quote: 	
		  >The cord method has a long history  of not failing, and at the speeds we 

>fly, it is surely not an issue


	




Even at the speeds Kolbs fly, there are documented rib stitch failures. 

Yes, rib stitching has a long history, but I personally know of two Kolb 

aircraft that suffered failure of rib stitches on top of the inboard ribs, 

probably caused by prop drumming, or improper rib stitch technique.



One may use whatever method they desire, but I will stick to fabric rivets 

on my Kolb.



john h

mkIII

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

WhiskeyVictor36(at)aol.co
Guest

Posted: Wed Jul 21, 2010 8:23 pm Post subject: Rib Stitching

In a message dated 7/21/2010 12:41:05 P.M. Eastern Daylight Time,  richard(at)bcchapel.org writes:

   	  Quote: 	
		     Here are pictures comparing two adjacent ribs, one the riveted tip    rib, and one stitched, the finishing tape has not yet been ironed.    

   Richard,

    

   I noticed that the first picture showed pinked edges on the    finishing tape, while the second picture showed straight edged    tape.  Are these on the same plane/wing?

       

   Bill    Varnes

Original Kolb FireStar

Audubon NJ

Do Not    Archive



	


  [quote][b]

Richard Pike

Joined: 09 Jan 2006
Posts: 1671
Location: Blountville, Tennessee

Posted: Thu Jul 22, 2010 6:03 am Post subject: Re: Rib Stitching

[quote="WhiskeyVictor36(at)aol.co"]In a message dated 7/21/2010 12:41:05 P.M. Eastern Daylight Time,  richard(at)bcchapel.org writes:

   	  Quote: 	
		     Here are pictures comparing two adjacent ribs, one the riveted tip rib, and one stitched, the finishing tape has not yet been ironed. 

   

   Richard,    

   I noticed that the first picture showed pinked edges on the finishing tape, while the second picture showed straight edged tape.  Are these on the same plane/wing?

       

   Bill    Varnes

Original Kolb FireStar

Audubon NJ

	




Yep. I wanted to use bias tape on the final outboard rib, as the fabric at the front drops off at a fairly steep angle, and the straight tape would wrinkle badly. Unfortunately, the only bias tape I have has pinked edges, so it will be slightly different from the rest of the tapes, but I don't think it will show much after it is painted.

Good catch.



Richard Pike

MKIII N420P (420ldPoops)

Richard Pike

Joined: 09 Jan 2006
Posts: 1671
Location: Blountville, Tennessee

Posted: Thu Jul 22, 2010 6:31 am Post subject: Re: Rib Stitching

 	  John Hauck wrote: 	
		  

Maybe if both systems are using the same width reinforcing tape.  However, I believe 1/4" reinforcing tape will not be as strong as 1/2".



john h

mkIII 	




I believe you are right. Now we are both happy.   



Richard Pike

MKIII N420P (420ldPoops)

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