> > Isp is units system independent
>
> Bzzt. Wrong again, I think :)

Often, maybe.
But not this time.

What I meant was that if you abuse the units so that the answer comes
out in "seconds", as "the industry" often does then

*If* 1 lbm of propellant has an Isp of 300 seconds when tested
*then* 1 kgm of it will have an Isp of 300 seconds using the same
(incorrect) reasoning
and 1 gram of it will have an Isp of 300 seconds,
etc.

My point was that by fudging the units they have effectively
eliminated the factor of g and made it essentially unity for this
purpose.
The units do NOT produce "seconds" when properly calculated but the
fudged system is units system independent.

Not something that's of much use in many other cases.


         Russell McMahon
--=20
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.