Does anyone no a company that sells 3/4" diameter carbon fiber tubes, or squar tubes. If you do, please give me a link.

Don't know if you wanted 0.75" inside or outside but here's one.

http://www.cstsales.com/carbon_composites-ss4.html

Gliderguy,

Thanks for the link, but thats a little bit pricy.

Maclean Quality Composites has the same tube for less than half of CSTs price.

Phil Barnes,

thanks, that's much cheaper.

Let me tell everyone what it's for. It's going to be the main spare for a 100" depron glider. So I also need something lite. Does anyone think A flat carbon fiber spare sandwhiched between two wood spares would be lighter, but still strong.

"It's going to be the main spare for a 100" depron glider."

A spar with 3/4" diameter tube is many times overkill in weight, cost and strength. Forget it!

Use a spar with three parts. A spar has two carbon bar sparcaps and vertical grain balsa between the sparcaps. See:
http://www.deltronix.net/cgi/acp_display.exe

I would suggest 1/4" vertical grain balsa (~3/4" high). Two pkgs. carbon CLT1-41, CLT1 .028" To .007" THICK x 48" LONG 1/4" (2/pkg), $7.19 for a total of $14.38.

Such a spar is more than enough strength and stiffness. Glue the carbon to the balsa with laminating epoxy (15 minute or more pot time).

Along the same line of thought, I need a slip fit set of tubes with an OD of about .500 inch which will see very large bending loads.
Which is stronger, roll wrapped or protruded, whats the difference?
I can't seem to a close or good fit from most of the suppliers, any ideas?

Another good source might be Don Richmond at HiLaunch . Don makes some 1/2" ID tubes that are identical to the other tubes except that they are a few thousandths oversize so that they can take a 1/2" joiner without sanding the joiner down to size.

I have some of the Hilaunch 1/2" tubes and I have tubes from MacLean Quality Composites (MQC) in a number of sizes. I just checked them for telescoping fit possibilities:

The 7/16" MQC tube does not quite fit into the 1/2" MQC tube but it might if you sanded it quite a bit. You would probably need to sand off the outer finish and maybe even a bit of carbon to make the fit.

The 7/16" MQC tube will almost slide into the 1/2" Hilaunch tube. It certainly would fit if you just sanded off the outer rough texture on the 7/16" MQC tube.

The 1/2" MQC tube would probably fit into the 9/16" MQC tube with a bit of sanding work. You would certainly need to sand all of the rough texture off but maybe no significant amount of carbon.

Or just call Don Richmond and see if he can help.

A pultruded tube has all of the fibers running longitudinally so it has little bursting strength. Wrapped tubes will generally have some glass or other wrap with cross fibers that wrap around the tube or the carbon fibers have a slight spiral wrap to give the tube bursting strength. You would not want a pultruded tube as an outer part of a joiner tube system unless you wrapped it with something on the outside for bursting strength. I'm not sure about a pultruded tube as the inner tube of a joiner system but the thought gives me a creepy feeling. sclt

Ollie,

thanks for the info. I can find most of this stuff at the local hobby store. time to get the foam and the CA.

used sporting goods.....
composite golf club shaft.
cheap with many diameters and more length than you'll need.
Check it out

Kite builders use these sorts of bits all the time.

Try this site... I've purchased from them in the past, with good service.

http://www.kitebuilder.com/catalog/i...27204b37b20b75

Try these guys, http://www.acp-composites.com/, they are pretty good to work with.

David Layne