Sopwith rib question

[baldeagle]

What is the thickness and material of the Sopwith rib webs, and what are the dimensions of the cap strips?




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[Nick]

Originally Posted by baldeagle

What is the thickness and material of the Sopwith rib webs, and what are the dimensions of the cap strips?
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Depends on the type I guess, and which ribs.
The Snipe’s wing rib webs are birch 3 ply and an oddball size of 3/20”, the empennage ribs are 1/8” webs.
From memory I think the Pup & Camel ribs are 3/16” birch ply but could be wrong there.
The Capstrip on the standard ribs is 3/16” x 3/8” spruce, with a rebate routed to take the ply webbing. I think that part at least is fairly standard on most types.

Cheers, Nick

[baldeagle]

Thanks Nick, I was looking at the Redfern N.17 drawings the other day and they call for 1/4" birch plywood rib webs, which seemed like overkill to me.




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[Leatherhead]

For the Camel's main plane ribs (long), the webs are, like the Snipe, 3/20" thick, 5-ply. The caps are 5/8" (width) x 1/8" (thick). For the Pup, the webs are 3/16" ply. The caps are 1/2" x 3/16".

[karrart]

Originally Posted by baldeagle

Thanks Nick, I was looking at the Redfern N.17 drawings the other day and they call for 1/4" birch plywood rib webs, which seemed like overkill to me.




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Hardesty gives the Nieuport 17 web thickness as 5mm, so 1/4" seems a little bit of an overkill.
Robert Karr
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[Leatherhead]

Notice on sheet 8, the leader pointing to the rib web with the text "4mm poplar web or birch"......above that is says 1/4" marine plywood may be used. Maybe what Redfern was thinking was if you can't get 4mm aircraft-grade ply, then 1/4" marine grade was the next best substitute. I think 3/16" or 5mm aircraft-grade ply is the way to go.

[JohnSShaw]

The Sopwith drawings state for the standard Camel ribs 3/20th Birch ply with 3/8th x 1/8 capping stips. The root ribs and other special ribs have different sizes of capping strip and ply.
I have just made 240 of them.

John

[Maxim08]

Leatherhead,
On sheet 7 it clearly states: 'all material on this sheet is 1/4" marine or aircraft plywood'. Sheet title: 'Ribs for 17/24 bis.'
Considering that the D VII ribs are 1.2mm, this seems very, ahh, robust.
Regards,
John

[j ferguson]

I would be very cautious about using "marine" plywood for anything in a plane except maybe ballast. I use it all the time on Arcadian, but the specs must be very loose about voids, knots, gaps, etc in the plys. Principle distinction of the stuff is the glue is more water resistant than ordinary plywood. It doesn't delaminate quite so quickly.

This does not mean that there might not be really good marine plywood, but there is, for sure, really crummy marine plywood.

John

[Albatros_Ace]

Originally Posted by JohnSShaw

The Sopwith drawings state for the standard Camel ribs 3/20th Birch ply with 3/8th x 1/8 capping stips. The root ribs and other special ribs have different sizes of capping strip and ply.
I have just made 240 of them.

John

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