right, so, you lay up a ply of 45's to give it torsional rigidity, then the rods at 12, 3, 6, and 9 o'clock to give it bending strength, and then another layer of 45's depending on strength etc, you can add more plies.
--- On Sat, 3/17/12, Paul <This email address is being protected from spambots. You need JavaScript enabled to view it.> wrote:
From: Paul <This email address is being protected from spambots. You need JavaScript enabled to view it.>
Subject: [Carbondragonbuildersandpilots] Re: CDII -fuselage
To: This email address is being protected from spambots. You need JavaScript enabled to view it.
Date: Saturday, March 17, 2012, 11:46 AM
If you want to build a tube from CF, it is really simple. Before beginning my search for a glider to build, I have almost exclusively built sailboats and racing dinghies often use CF or cf and fiberglass in alternate layers. To make an internal form you take a piece of pipe the length you need and buy foam insulation to bring it up to the desired diameter. Sometimes you have to add layers of soft foam in order to achieve the right size. Make sure it is one that will dissolve in either gasoline or acetone (buy a little piece and soak it to test). Now you wrap this in saran wrap or any similar cling film.
CF and FG are both available in knitted tubes that can be expanded or contracted to meet the necessary diameter. Add layers one at a time painting on thin resin until the fabric's weave is full, then apply the second layer of cloth, repeating the process until you have made up the desired thickness.
Allow this to cure fully while turning the tube every few minutes to prevent sag from the resin pooling. One builders had adapted a barbecue rotisserie unit to keep the tube rotating slowly until it was fully cured.
Once cured, the core is removed by standing the tube on end and pouring the solvent onto the foam. The bottom end should be in a bucket to prevent this toxic mess from getting on the ground. The pipe in the center can sometimes be pulled out before using the solvent on the foam but usually that won't happen until the foam has mostly melted.
Now rinse out the inside of the tube. You should be able to pull out the saran wrap now, but if not it is light enough not to be a problem.
If you wanted to incorporate graphite rods into this process, they could be taped in place before putting the CF sock over the core. If small grooves are made in the foam, these rods would be completely hidden beneath a very smooth CF shell with as little as one layer of fabric since that is now a secondary strength medium, serving mainly to fix the position of the CF rods.
