Re: [amsat-bb] AO-7 10m bcn, switch-on delay

[Jim White <jim@xxxxxxxxxxxxxxxxxxxxx>]

At 02:35 AM 6/29/02 -0700, Paul Williamson wrote:
>At 07:41 AM 6/29/2002 +0000, Richard W L Limebear wrote:
>>  The polar flipover, for want of a better term, could cause
>>very poor sun angles ...
>
>Good point.
>
>If AO-7's magnets work like Microsat magnets, the behavior is a LOT more 
>complicated than just flipping over at the poles. The flexible WOD 
>capabilities of the Microsats enabled some rather extensive analysis, 
>though I'm not certain we ever settled conclusively on a single 
>interpretation of the data. Maybe somebody can shed some more light on 
>this, so we can compare the Microsat results to the AO-7 observations.
>
>73  -Paul
>kb5mu@amsat.org


Not quite, but close :)


Satellites with this stabilization method do not flip over at the poles, 
they rotate 180 degrees in-plane when near the equator.  We know exactly 
how this works, the angles predicted by the magnetic model agree exactly 
with those observed in AO-16 and the other Microsats.  See my paper 
"Microsat Motion Stabilization and Telemetry".  It was in the Journal I 
think in 1991 and presented at the Houston AMSAT Symposium I believe that 
year.  See www.coloradosatellite.com, bottom left corner link for the full 
paper.

In that paper there is a formula the predicts the angle of the Z axis of 
the satellite to nadir.  And there is a chart that shows solar panel 
current data from AO-16.  These data show clearly which side gets sun at 
each point in the orbit.  The AO-16 data are particularly good for this 
because there are panels on all sides of that satellite.

Jim

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