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Re: Wing ribs 09 Dec 2013 01:09 #418

I don't know how Atos fabricate their hollow ribs (I'll take a look at a friends VQ next time we're flying), but one process that might work is to form them around a foam core as already described and then (through a couple of small holes at non-critical locations) to inject a solvent (acetone) to remove the PVC foam, which comes out as a gloopy snot! I read about this in John Wanberg's Composite Materials Fabrication Handbook #1 of 2 (available from Amazon.) I'm not sure the extra work would be worth the effort given the weight of the foam involved.

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 Rick Mullins
Sent: 06 March 2012 12:21
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Subject: Re: [Carbondragonbuildersandpilots] Re: Wing ribs




I don't know if you are familiar with the ATOS hang glider. They fabricate carbon fiber ribs that have a hollow box structure and are very light and strong. I always wondered how they make them. I suppose they vacuum form them over a male mold which would give a U shape, Then after removing them from the mold you then somehow do that last surface, but how do you keep the cloth from collapsing without internal support?


: Philip Lardner <This email address is being protected from spambots. You need JavaScript enabled to view it.>
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Sent: Monday, March 5, 2012 7:55 PM
Subject: RE: [Carbondragonbuildersandpilots] Re: Wing ribs




I investigated pultruded carbon tubing also and even purchased a sample:

www.easycomposites.co.uk/products/carbon...section-8mm-7mm.aspx

This stuff is incredibly light and would be ideal for the straight sections of the ribs and particularly or making up the flaperon ribs. There are two down-sides to this stuff: at 0.5mm wall thickness it is rather easy to crush, and the other problem is... the price! I calculated the number of meters of this stuff I'd need and then hid behind the sofa when I worked out the price! It *is* a beautiful product, though, and very light weight.

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 Kenny Andersen
Sent: 06 March 2012 00:05
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Subject: Re: [Carbondragonbuildersandpilots] Re: Wing ribs



Karl,
I wasn't referring to the rod, but to the tubing. The rod bends quite easily, but the tubing does not. I'm thinking something along the lines of the basic wooden rib only mad from hollow composite. In this application (as opposed to the wing spar) there would be a minimum length to get all of the load sheared into the rod. I'm thinking MAYBE the uni tape might be more apropos on the rib caps?

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