Hi Karl,

I did think about using carbon rod for the ribs but decided against it when I built a test rib out of straight graned wood (not spruce). The problem is that the wood (and I think any straight graned material... like CF rod) does not conform perfectly to the rib contours when bent over the internal diagonals and constrained at the ends by the other straight pieces (at the spar and rear ends). To get the wood to conform perfectly I believe a certain amount of soaking in hot water or steaming and forming would be needed. The natural curve of the wood when stressed deviates by 3-4mm in places. You can see a few photos of what I'm talking about in my photos folder.

xa.yimg.com/kq/groups/12246891/sn/811004...e/Lower+rib+cap2.jpg
xa.yimg.com/kq/groups/12246891/sn/921689...e/Upper+rib+cap1.jpg
xa.yimg.com/kq/groups/12246891/sn/133422...e/Lower+rib+cap1.jpg
xa.yimg.com/kq/groups/12246891/sn/285994...e/Upper+rib+cap2.jpg

...I have a sneaking suspicion that you can't steam carbon rod into shape too easily!! Also, in short lengths (like the rib caps) carbon rod is horribly stiff and difficult to bend to shape - I forsaw nasty thinks happening with all that kinetic energy pent up in rods held in place by only a few panel pins - and god forbid one of those joints should let go in flight!

You'd also need to gusset the joins (just like the wooden ones) to reinforce the joins and provide a little lateral stability for when the rib starts to twist under extreme load... and there are an awful lot of little pieces of CF rod to cut (and bevel the ends) very accurately.

I'm pretty happy with the new female mould rib fabrication method I'm developing - it's quick and easy! I'm making a full set of moulds right now and hope to turn out another test rib using this method by the weekend.

Phil.

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From: This email address is being protected from spambots. You need JavaScript enabled to view it. [This email address is being protected from spambots. You need JavaScript enabled to view it.] On Behalf Of KarlS
Sent: 05 March 2012 16:22
To: This email address is being protected from spambots. You need JavaScript enabled to view it.
Subject: [Carbondragonbuildersandpilots] Wing ribs



Nice work Phil and nice drawings Charlie.

I want to share a couple ideas.

1). Could you not make truss ribs out of pultruded graphlite rod. Just some simple pin jigs and use carbon fiber cloth at the joints?

2) I uploaded some photos that shows how I built some wing ribs. A full rack of ribs that really only took a few hours. The concept was to cut a slot and then drop in the spar. It all jig built and really pretty easy to do. Here's the link to our photo section.

groups.yahoo.com/group/Carbondragonbuild...m/777507385/pic/list

Both of these ideas are for discussion purposes for CDII.

Regards,

Karl