On Wed, 10 Jan 2007 19:45:06 -0600, Henry Spencer wrote
(in article ):

(The other is also related to thinner air: rocket engines are more efficient

with less back pressure.

My undergraduate propulsion prof would be gagging at your use of the
term "back pressure" Henry. He used to almost spit and fume when
someone let it slip. :-p

--
Herb Schaltegger
"You can run on for a long time . . . sooner or later, God'll cut you
down." - Johnny Cash
http://www.angryherb.net