Re: Is a 'dry' compressed -air rocket feasible?

Cheers,

Look up Ziolkovsky's (Tsiolkovsky) rocket flight equation. Rockets fly 
because mass gets expelled at high velocity from one end - the larger the 
mass and the higher the velocity - the better. Pressure is involved only 
indirectly. 
 http://search.biography.com/cgi-bin/frameit.cgi?p=http%3A//search.biography
.com/print_record.pl%3Fid%3D11907

Basically, compressed air rocket would not work too well because the 
reactive mass would be too small relative to the mass of the rocket itself. 
If you liquify the gas you might obtain enough thrust. Water-air rockets 
work so well because they use relatively heavy liquid as their reaction 
mass.

Hope it helps.

A.G.E.