Seeking materials; long fiber Rods?

Stuff it full of old fishing poles. Or a piece of wood that will fit.

 

Hey.... Bamboo? I could douse it in some West System epoxy.

 

That may well work, another option would be to use a wood core and wrap it in glass. The fibre glass rods will be heavy comapared to the aluminium tube

 

I've got a 1/2" dia, 10ft long fiberglass rod coming.
I'm going to try and capitalize on its tensile and compressive strength by pinning it inside the aluminum tube:

The fiber rod is flexible, but in order for it to flex with the aluminum tube, at least one end will need to be able to "slide" freely because the arc that they both for will be different. By securing both ends, and possibly pre-loading the rod, the aluminum spar wont be able to flex without compressing the fiber rod. It will still be able to flex, but it should be limited.

 

You might be surprised by how heavy that will be.... on the other hand you wont be able to break it if it is a good rod

 

Nah I wont be surprised, I've just bit the proverbial bullet and settled for the $11 solution.