Subject: Re: Truss construction for low weight.
From: Henry Spencer <henry@zoo.toronto.edu> 
Date: Apr 01 1996
Newsgroups: sci.space.science

In article <4jdafa$m1@newsbf02.news.aol.com> ronstirs@aol.com (RonStirS) writes:
>Since mass is an important concern of any space based construction project,
>would it be better to have pressurized tubing used in place of conventional
>materials? ...

Unfortunately, probably not.

For one thing, it will eventually be punctured by space debris or
micrometeorites unless it is protected.

For another, in most real structures stiffness is more of a concern than
strength, and a long thin pressurized tube is not especially stiff unless 
quite high pressure is used. 

There are tricks that can be used.  For example, I've seen a solar-sail
design in which the booms -- carrying very light loads, but necessarily
very long -- were inflated tubes made of composite prepreg material.
Inflation would spread them out to the right shape, after which the
resin in the prepreg would be cured by solar UV, resulting in rigid tubes
which would retain their shape and physical properties without internal 
pressure.
-- 
Americans proved to be more bureaucratic           |       Henry Spencer
than I ever thought.  --Valery Ryumin, RKK Energia |   henry@zoo.toronto.edu