Newsgroups: sci.space
Path: utzoo!henry
From: henry@utzoo.uucp (Henry Spencer)
Subject: Re: Where the hell are electric-ion thrusters????
Message-ID: <1989Aug29.163942.6919@utzoo.uucp>
Organization: U of Toronto Zoology
References: <8908241857.AA02943@fermat.Mayo.edu> <1989Aug25.183710.3054@utzoo.uucp> <4256@utastro.UUCP> <6091@lynx.UUCP> <4271@utastro.UUCP>
Date: Tue, 29 Aug 89 16:39:42 GMT

In article <4271@utastro.UUCP> terry@astro.UUCP (Terry Hancock) writes:
>* I would like to take this opportunity to rag on the engineer who
>decided to cancel 1 lbf with 1 lbm and thereby arrive at seconds as
>the unit of Specific Impulse...

Perfectly legitimate cancellation; the problem is that the *unit* is
silly.  Use exhaust velocity instead -- not only is it expressed in
sensible units, it's physically meaningful to boot.
-- 
V7 /bin/mail source: 554 lines.|     Henry Spencer at U of Toronto Zoology
1989 X.400 specs: 2200+ pages. | uunet!attcan!utzoo!henry henry@zoo.toronto.edu