.......... :-)) wrote:
I have contemplated something similar.

I think you would be best to wind the tubes using a carbon / glass
tow
material and epoxy around a mandrell. Tow would be a lot cheaper
then
wrapping the tubes in cloth and would allow the properties of the
tube to be
optimised by changing the winding angle.

Pro's and Con's ....

It is going to cost more than alumnium.
Might save a little weight.
Joints will be hard to make at intersections of tubes.
The composite tubes will lake the ductility of the alumnium tubes and
hence
crashworthiness will be compromised.


Wrapping in cloth or tape would be a lot easier and faster if doing
the layup by hand. It would also be trivial to orient it so that
half the fibers of the cloth or all the fibers of unit-directional
tape run the length of the tube to maximise bending strength.

Before doing anything of the sort I want to be able to calculate
that strength, hence the original question.

Joints could be made with tows/cloth/tapes to fabricate saddle-like
fittings perhaps in-situ.

Crash-worthiness remains an important issue.

--

FF