[amsat-bb] Re: AMSAT history
n4hy at idaccr.org
Mon Oct 30 08:32:08 PST 2006
I have not uploaded my AO-40 directory yet. It is insufficiently
complete. I have pictures I think almost no one else has seen and I
want to flesh these out a bit before I upload them.
In the Phase 3A, AO-10, AO-13 directories you will see curved tubes in
the arms of the spacecraft near the tips. These tubes have their ends
welded closed. They have glycerin in them.
As the spacecraft undergoes maneuvers from the motor firings to
magnetorque attitude control adjustments, the spinning spacecraft tends
to wobble. When the launcher pops us off the vehicle, it can easily
impart a wobble. This wobble is called nutation. By placing the curved
tubes in an arc parallel with the principal spin axis for the
spacecraft, when there is this wobble, it causes the glycerin to move
up and down in the tube. This movement of this viscuous fluid in the
tube converts the angular momentum of the wobble into heat and "dampens"
the wobble out. This wobble is called nutation, and these tubes are
called nutation dampers. The shape, placement, etc. are optimized to
maximize coupling with the spinning frame and to get enough damping so
that the wobbles are gone in a few minutes.
Jim Jerzycke wrote:
> Yes, nostalgis seems to be part of getting older.
> I have one question concerning the AO-40 pictures. I
> see a curved pipe with "crimped" ends in many of the
> pictures. What is/was it for?
> 73, Jim KQ6EA
> --- Bob McGwier <n4hy at idaccr.org> wrote:
Robert W. McGwier, Ph.D.
Center for Communications Research
805 Bunn Drive
Princeton, NJ 08540
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