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From: fcrary@earthquake.Berkeley.EDU (Frank Crary)
Newsgroups: sci.space.shuttle
Subject: Re: Propellant velocity
Message-ID: <1991May23.061559.22822@agate.berkeley.edu>
Date: 23 May 91 06:15:59 GMT
References: <12344@uwm.edu>
Sender: root@agate.berkeley.edu (Charlie Root)
Organization: ucb
Lines: 32

In article <12344@uwm.edu> markh@csd4.csd.uwm.edu (Mark William Hopkins) writes:
>
>   What is the velocity of the fuel propellant relative to the ship, in the
>case of (1) fuel from the booster during boost, and (2) fuel from the ship
>itself during orbital flight?
>
>   How fast can NASA-generated technology expel propellant?
>
>   What does the latest research on this issue have to say?

The exhaust velocity of the shuttle engines are as follows:
(note convert to specific impulse by dividing by 9.8 m/s^2)
Soild Rocket Boosters: 2700 m/s (approximate)
Main Engines (used on take off only): 4400 m/s
Orbital Manuvering System: 3070 m/s
Reaction Control System: 2550 to 2750 m/s

The highest exhaust velocity produced by a NASA rocket was

9600 m/s operational, upto about 10500 to 11000 m/s in very limited
(and low thrust) conditions.
This was the NERVA (Nuclear Energy for Rocket Vehicle Applications) static
test reactor/engine. The program was terminated with NASA's post-Apollo
Mars mission hopes.

On paper studies say many things. Numbers as high as 50,000 m/s are projected
but this involves very long term and risky research and development. I
suspect that as far as the next 15 to 20 years go, a 14,000 m/s solid core
nuclear thermal rocket is about the limit.

				     Frank Crary
				     UC Berkeley