Hi Phil,
Don't get me wrong I think your processes are great and very impressive.

It was mentioned cnc routing foam which is a great idea. Cheap and fast.

I have incorporated some graphlite rod into my current project. It's a 1/2 scale model. The landing gear is a composite structure of foam, graphlite rod, and one layer of 6 oz fiberglass cloth all vacuum bagged.

Here's a video of some testing I did for my personal peace of mind.



The interesting fact is that each one of these legs weigh only 4 oz each. They will be carrying an 80 lbs aircraft.

My thoughts are as follows. A cnc cut rib with channels on the corners to lay the correctly sized graphlite rod into and then vacuum bag the assembly. If the rod is sized correctly to do the job I am sure it would bend without distortion. Once vacuum bagged with carbon or fiberglass it would be almost guaranteed not to deform.

Box structure/beams could be built similar to my landing gear to make an extremely light airframe.

I'm just tossing ideas out there. That is all.

Also on your ribs you could router radius's on the internal part of the rib. I router foam all the time on my router table.

Not sure if that would make them stronger or weaker but just an idea.

Karl

--- In This email address is being protected from spambots. You need JavaScript enabled to view it., "Philip Lardner" wrote:
>
> 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.
>
>
> _____
>
> 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...ots/photos/album/777
> 507385/pic/list
>
> Both of these ideas are for discussion purposes for CDII.
>
> Regards,
>
> Karl