Re: S.P.E.A.R.C.O.intercooler guys?? -Reply

[Gross Scruggs <GScruggs@wposmtp.nps.navy.mil>]

Bob,  very informative post!  Excellent point about temperature scales, absolute
vs relative and their relative heat content... easy to overlook those things. 
Long dormant synapses came to life while reading it... those classes were a long
time ago.

For the purposes of this list, however, there is one critical relationship that
remains unsaid.  Your derivation left me with the impression that pressure and
temperature have equal, although opposite, influences on density.  As I recall
their influences are not equal.  

For instance, for long range effeciency aircraft need to fly in the least dense
air mass they can reach.  Usually this is around 34-37k feet where the
tropopause occurs.  Air mass temperature decreases from a high at sea level to
the tropopause where it stays essentially constant into exoatmospheric space. 
Pressure, however, decreases from a high at sea level to a low some numerous
miles in space, well above the tropopause.  Apparently temperature has a greater
effect on density than does pressure.

If one has to address a trade off in a turbo/intercooler application, ie, do you
go for more pressure or more cool, which way is most productive?  I realize this
is not quite an apples-to-apples swap in terms of efficiency and cost, but which
factor has the greatest influence?

Do I spend my money on a bigger turbo, or do I try to find better ways to cool
the air mass that I've already compressed?

Again, excellent info!

Regards, Gross