Rib stitching

[Brett]

I have just been watching a heap of you tube videos to try and work out how to do the rib stitching knots and so forth as the poly fiber book seems a bit hard for me to work out. I came across this method and was just wondering what people in the know think of it ?

 

It's quite a long video but the important bit is about half way through if you wanted to skip the marking business.

 

-Thanks

 

 

[dazza 38]

There are some great Videos on you tube.Like Bretts one above.They come in very handy.

 

 

[old man emu]

Brett,

 

A couple of things from that video, and some of the others on the same page.

 

Rib stitching is not difficult, just tedious.

 

We do a lot of fabric work. We don't suspend our wings vertically. We put them on trestles and work from leading to trailing edge. We use straight needles and waxed cord. And we don't go under the fabric between stitches. That slows you down, and the cord is hidden by the reinforcing tapes that are applied later.

 

I haven't read the Polyfibre book, as we use Ceconite, but I imagine that the diagrams for the Modified Seine Knot are the same in both as the diagrams come from the FAA Maintenance & Repair Manual.

 

I have a series of photographs showing the steps in tying these knots. They are kicking around in a computer somewhere. I'll try to find them and post them here.

 

If you were near Sydney, I'd invite you to call in to out hangar for some instruction.

 

Old Man Emu

 

 

[old man emu]

This month's EAA magazine has an article with pictures on one way to tie a seine knot. However, the method used is not the one I have been taught, but it's worth a try.

 

I have been gathering together some fabric and a dummy section of wing so I can make a video and document showing our way of tying this knot.

 

Old Man Emu

 

 

[Brett]

That sounds great ,,, Ive been concentrating on fabricing the fuse at the moment so I have time before I need to get serious with the wings ,,

 

 

[old man emu]

Been busy the past two days. I hope to get some ME time over the weekend so I can take some pictures and start writing an article.

 

OME

 

 

[Old Koreelah]

Just to throw a spanner in the works... why stitch at all? I tried to learn the damn knots and practiced on a spare rib, then gave up. I made a test panel using strews and washers, stitches and ordinary pop rivets and washers. The pop rivets caused least rib splitting and were the lowest profile, as well as the easiest, and they're pretty easy to drill out if need be...

 

 

[old man emu]

Just to throw a spanner in the works... why stitch at all? ...caused least rib splitting ...

And there, my friend is the flaw in your otherwise flawless plan.

 

Blind rivets, Fabric clips and screws can be used to attach fabric to METAL RIBS.

 

If they are used on wooden ribs (and, I suspect, fibreglass ribs) they will cause splitting of the material and a consequent weakening of the area of the rib around the hole.

 

Some aircraft manufacturers designed their metal ribs to allow the use of these things en lieu of stitching, such as:

 

Martin Fabric Clips - Aeronca/Champion, Piper, Stinson and Taylorcraft.

 

Cessna Wing Clips - C-120, 140,170

 

For low speed aircraft, some might consider gluing the fabric to the ribs. What one is relying upon is the strength of the bond made by the glue between the rib and the fabric.

 

Old Man Emu

 

 

[Old Koreelah]

I am only speaking from my limited experience. As I mentioned, I tested several attachment methods on a spare rib. I pre-drilled all holes; the pop rivets caused no splitting, but tiny screws did. After the application of covering tape the pop rivets resulted in the lowest profile. I tested drilling out rivets and its seems no harder that removing screws or tape. This aircraft is experimental, so I experimented.

 

 

[old man emu]

Old Koreelah,

 

Experimental or not, just think what you are doing to the strength of the rib when you put a hole in it. You are breaking the strands of cellulose fibre which give the timber its strength. You are introducing a point of weekness into the structure.

 

It's true that in making a rib, one nails pins into the sticks when positioning reinforcing webs, and this fractures the wood. But the function of the nails here is to hold the webs in place under moderate pressure while the glue sets. Any possibility of stress failure in the wood is reduced by the holding power of the web and the glue joint.

 

Consider also the thousands of fabric covered, wooden wings that have been made since 1900. The vast majority of these have been stitched, and the rest may have been glued. ONLY THOSE MADE WITH METAL RIBS would have had the fabric secured with clips, screws or pop rivets.

 

I agree with you that screws or pop rivets would not produce the lump that is caused by the lacing cord crossing over the cap strip. In fact the ribs designed to be used with Martin Fabric clips have a groove down the middle to house the clip so that it doesn't stand proud of the wing surface when the job is done. However, that is the trade off one has to make. With attention to detail, a very neat job can result.

 

I salute your having a go at experimenting with an aircraft build, but please don't go against the experience of the Ages.

 

Old Man Emu

 

A stitch in time saves nine.

 

 

[old man emu]

This weekend I'm working on a Guide to Rib Stitching.

 

Hopefully I'll have it ready to post on Monday night.

 

OME

 

 

[old man emu]

A Practical Guide to the Modified Seine Knot

 

Due to the limitations of the size of file that can be posted on this site, I have had to publish the guide to tying the Modified Seine knot on a blogsite.

 

Here is the link:

 

http://www.oldmanemu1.wordpress.com

 

Old Man Emu

 

 

[Chird65]

OME,

 

What a great bit of work. It must have taken a bit of time to record it all. If I need to do any stitching in the distant future I'll reference this .

 

Chris