[amsat-bb] Kick motors on Oscars: How does attitude control work?

Burns Fisher burns at fisher.cc
Sun Sep 22 13:19:07 PDT 2013

There has been a lot of discussion about AO-10, 13, and 40 (and maybe
others) with various kinds of apogee kick motors (and inclination changers
etc).  Rather than fanning any flames, I just want to ask a question:  If
you have a motor of a few hundred Newtons, how to you keep the attitude
stable during the burn?  For that matter, how do you get the attitude
correct for the start of the burn?  I would not think that electromagnets
operating against the earth's magnetic field would have enough power with
such a large motor.  Obviously it depends on the balance of the satellite
relative to the position of the kick motor, but still...was the balance
really good enough to allow magnetic attitude control?  Was it active (i.e.
with feedback)?  Does that imply a rate gyro?  (No MEMS then, I suppose).

Thanks in advance for the technical history lesson...


Burns W2BFJ

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