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Re: Bravo to the command team!



----- Original Message -----
From: Jan A. King <jan.king@blastoff.com>
To: Ken Ernandes <n2wwd@mindspring.com>; Richard D. Burgan <wc8j@raex.com>;
<amsat-bb@AMSAT.Org>
Sent: Wednesday, January 10, 2001 5:36 PM
Subject: RE: [amsat-bb] Bravo to the command team!


>> -- Earth Gravity (using up to an 8th-order gepotential model)
>> -- Lunar & Solar Gravity
>> -- Atmospheric Drag
>> -- Solar Radiation Pressure


> [...After subtracting off the real effects of the above itemized
> perturbation
> forces (which are not zero).  In my experience estimating drag effects is
> difficult, especially near solar max. which is (unfortunately) where we
are.


Estimating drag long term can be difficult because even the most
sophicticated atmospheric models are not perfect.  But AO-40 only
experiences significant drag effects for a brief portion of the orbit, so
imperfections in the model are not critical.  However, the "thrust" affects
the entire orbit and the other forces affect most or all of the orbit to
some degree.

The bottom line is that adding a constant thrust acceleration fit the
observed changes to AO-40's orbit.  The direction of this thrusting force
corresponded to a mass expulsion from the 400N motor's nozzle.

73, Ken N2WWD





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