Re: SL-16
Tony Beresford (starman@camtech.net.au)
Sat, 14 Aug 1999 13:41:37 +0930
At 07:46 14/08/1999 , James Husnay Sr. wrote:
>Has any other "naked eye" RB or satellite ever tumbled as fast as this
>one is? And what causes it to tumble in such an out of control speed?
>Thanks in advance.
James and others,
USSR/CIS rocket bodies have had this behaviour since 1960.
Its a deliberate act to spin the rocket so it wont edge up on
the payload due to leaking fuel, not a fuel dump. The tumble period
increases( rotation rate deceases) because of eddy current damping.
The eddy currents are of course induced by a conductor( the rocket shell),
moving(tumbling) in the Earth's magnetic field. This process is exponential,
so the rate of change is proportional to the rotation rate, and it approaches
zero rate at infinite time, and quicker for shorter periods.
On payloads you can also have magnetic hysteris damping if
you have some magnetic material in it. The decrease in rotation rate is
the linear, and goes down to 1 rev per orbit.
Additionally of course long thin objects have a tendency to line up along
the graviational gradient. This of course = 1 roation/ orbit.
Since the Earth's magnetic field strength is an inverse cube relation ship,
these mechanisms have to compete with other weaker forces like radiation
pressure at GEO
Tony Beresford