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

“Dry”Air Rocket
Has anyone built a “dry” compressed-air rocket ie. a compressed-air rocket 
that did not also require water? Was it any good?

My understanding is that “compressed-air only” rockets tend not to fly too 
well as after the initial thrust spike the air pressure in the chamber falls 
sharply thereafter providing little sustained propulsion.

I have an idea to get round this: Divide the pressure chamber into two parts 
separated by a piston or put a balloon into a sealed bottle. During the 
“charging” of the rocket, as air pumped into lower part of chamber (or the 
balloon) the piston must move upward (or balloon expand) until pressure in both 
compartments equalises. Then upon launch the air rushes out of the nozzle, the 
air in the upper chamber expands forcing the piston down (or collapsing the 
balloon) and thus maintains constant pressure at the nozzle during flight.

Would it work ie. would it  improve flight performance and make the rocket go 
higher?

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