Re: Superbird A secondary flashes

Bart De Pontieu ((no email))
Mon, 22 Jun 1998 16:40:37 -0700 (PDT)

On Mon, 22 Jun 1998 wrote:

> I am sure Rob's assumption about the spin axis orientation of Superbird A
> is correct.
> Energy dissipation will make any object that spins in an uncontrolled way
> spin about the body axis with the highest moment of inertia. In the case of
> Superbird A, this axis must be perpendicular to the solar panels.
>      If a satellite's  operational spin axis is the one with the highest
> moment of inertia,
> this effect can be useful for passive nutation damping, if not, it can be
> lethal
> to a satellite and result in a so called "flat spin". Explorer 1 was the
> first satellite
> to fall victim to this effect and many followed.

What kind of 'energy dissipation' process are you thinking of? I've always
wanted to find a good text on what the nature of these is. I've never
found an article/book that explains these, except for assuming that
they are there.
Some sources seem to claim 'internal energy losses' and claim they are to
inelastic deformation. I can see where this is a problem for a satellite
with long booms/antennas, but not for rigid cylinders like third stages. 

Eddy current torques can do the same job, at least for cylindrical third
stages. And at least eddy currents are really there.

Can anyone give a good reference on this topic?

Thanks and cheers,
     Bart (