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Conference 7.286::space

Title:Space Exploration
Notice:Shuttle launch schedules, see Note 6
Moderator:PRAGMA::GRIFFIN
Created:Mon Feb 17 1986
Last Modified:Thu Jun 05 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:974
Total number of notes:18843

594.0. "Variation of Atmospheric Density with Altitude" by LHOTSE::DAHL (Tom Dahl, CDMS) Tue Jan 23 1990 17:01

I'm looking for data on how the density of the Earth's atmosphere varies with
altitude.  I have a table which lists the density  ratio (relative to standard
day sea level) for every thousand feet up to 100,000 feet (where, incidentally,
the ratio is 0.0132, i.e. 1% of seal level).

I'm now trying to extend this data up higher.  Does anybody know of a source
for such info?
						-- Tom
T.RTitleUserPersonal
Name		DateLines
594.1Some SourcesVOSTOK::LEPAGECosmos---is my jobWed Jan 24 1990 10:2011
    Re:.0
    	Try "The US Extension to the ICAO Standard Atmosphere". An
    abbreviated tabulation with graphs of this model to an altitude of
    about 300 Km (~985,000 ft) appears in "CRC Handbook of Chemistry and
    Physics". There is also a standard atmospheric model used by the US Air
    Force (whose official name escapes me right now). This table is
    published in the form of a book and should be found in some university
    physical science libraries.
    
    				Drew
594.2Found Data; it's for FLIGHT SimulatorLHOTSE::DAHLTom Dahl, CDMSThu Jan 25 1990 10:4830
RE:            <<< Note 594.1 by VOSTOK::LEPAGE "Cosmos---is my job" >>>

>    	Try "The US Extension to the ICAO Standard Atmosphere".

Thank you for the reference to the CRC book.  As for the ICAO Standard
Atmosphere, it does not accurately describe the Earth's atmosphere.  Rather, it
is a model which is approximate but known to be inaccurate (in substantial
ways, not just in the nth decimal point).  So I'd rather not use it.

As it turns out, in the CRC handbook just before the sections on the ICAO model
of the atmosphere, there is a small table of actually measured values (via
sounding rockets) for every 10 kilometers up to 160Km.  I should be able to use
this data.

By the way, I want the data so I can apply it to the VAXstation FLIGHT
simulator.  It currently models the atmosphere accurately to 100K feet, then
inaccurately up to 150K feet where a vacuum is inaccurately reached.  I'd like
to increase the high altitude accuracy because FLIGHT now can be extended to
extra-terrestrial simulation.  I have been working on a (computer) model of the
Apollo/Saturn V combination, and just last night, for example, I launched a
simulated Saturn V and successfully accomplished eleven real-time orbits of
the Earth (consuming 16 hours of CPU time -- FLIGHT is a real-time simualtor).
I wanted to use my workstation for other things and so I manually terminated
the orbital trajectory and re-entered; I wonder how long it would have gone.
Perogee of orbit was about 150 statute miles, speed at this point was 17,400
mph in a level path.  I didn't hang around to find out what the apogee height
was.  I suppose I could compute it; total distance travelled for 11 orbits was
364,250 miles, averaging 33,114 miles per orbit.  Total time was 16:39:35.63,
with an average of about 1 hour 31 minutes per orbit.
						-- Tom