The message
from "Autolycus" contains these words:

Stiffness is proportional to the fourth power of diameter for a round
beam in bending, so 3/8 to 1/2 inch is a factor of 4^4/3^4, or 256/81,
or 3 and a bit, as we engineers say (or pi, or root 10).

In other words - make the tube a bit fatter and it'll be a /lot/ stiffer.

--
Skipweasel
Pay no attention to that man behind the curtain.