Well, my problem is that I would like to build a lightweight structure for a telescope. One possible structure is truss serrurier structure, like this http://www.planewave.com/index.php?page=1&id0=0&id=4 . Another ideea is something even lighter, like this one http://www.alpineastro.com/LAZZAROTTI/Lazzarotti_Home.htm

I don't have any experience with different materials like Al, or carbon fiber, but I've startet to study this problem. The first ideea is to make a truss serrurier structure:
- three rings cutted from carbon fiber plates: one full disk (plate) at the end to hold the main mirror and two rings in the middle and at the top of the structure
- truss tubes in between
Tubes will be something like this ones https://www.easycomposites.co.uk/8mm-woven-finish-carbon-fibre-tube , pulllwinded or rolled.
The main problem is the ring elements and the back plate: must be light and strong. And I've concluded that single carbon fiber plate is not good. It must be a sandwich plate. I found this https://www.easycomposites.co.uk/foam-cored-carbon-fibre-panel but I don't understand: is fiber carbon on both sides?

The tube must hold a 11" (270mm) mirror at the back (~4kg) plus the focuser (~500g) and a small mirror at the top (~400g), Truss must be ~1m long and 350mm wide.

I plan to glue the tubes on the rings/plates in order to avoid drilling holes and weakening the structure or cracking the tubes.

I'll appreciate any help.
Thanks.

I've spend some time thinking and found this movie: www.youtube.com/watch?v=gCY8tLHyeJQ
This could be a good approach for bonding carbon fiber parts. The procedure will be:
- cut the parts in the proper shape
- glue them together in the right position
- cover the joins in carbon fiber sheets (2-3 layers) for strength and rigidity
Only carbon fibers parts will be used (tubes, rigid plates, angle sections), no other materials.

To be sure about the components I need for this:
- what type of carbon fabric should I use? This is ok https://www.easycomposites.co.uk/200g-profinish-coated-22-twill-3k-carbon-fibre-cloth ?
- what glue should I use? This is ok https://www.easycomposites.co.uk/rigid-5min-epoxy-adhesive ?
- what epoxy, hardener should I use? This is ok https://www.easycomposites.co.uk/el2-epoxy-laminating-resin or actually this skinning epoxy is required https://www.easycomposites.co.uk/xcr-black-epoxy-basecoat ?

The good looking is not important, I don't want so be shiny or smooth, only the strengts and rigidity is what matters.

Thanks for help

The foam CORED board, IS double sided.  I like the monopod designs, but you still need a windshield, or your thermal currents can really screw your image quality. I've got an 18" F2.5 ultra light mirror to try out at some point.

Lets try and design something from EasyComposites products to make something real. What optics have you got to work with ?

Steve

Hi,

18" F2.5 ?  

Hell of a fast mirror.

I'm going to make a test tube for an 8" F4 then 16" F4 if the first one goes well.

I was thinking of using sonotube as a mold.

Yeah, more soup bowl than mirror ;-)