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Leaking out the nozzle [was: Re:Bravo to the command team!]



Ken Ernandes wrote:

> The
> hypothesis was that since AO-40 has essentially the same orientation it had
> for the perigee boost thruster firing, a leak out the 400N thruster nozzle
> would have a positive acceleration at perigee and a negative acceleration at
> apogee...The amount of [estimated]
> thrust was varied in the calculations until there was a match to AO-40's
> observed orbital behavior.  This more or less corroborated the propellant
> leak hypothesis.  Furthermore, finding a good fit for the thrust gives an
> excellent estimate of the rate at which the propellant mass is being lost.

Wow...so the spin-up goes with the mass loss, the angular momentum of the fuel
is being transferred to the spacecraft on it's way to the engine, and the
orbital anomalies are due to reaction thust provided by vaporizing the leaked
propellant in the engine. So with the magnetorquers providing some attitude
control, the thrust we can't turn off can at least be applied to advantage
rather than disadvantage. Perhaps once the leaking propellant is exhausted, the
arc-jet can be used for further orbital goodness...although it will apply thrust
in essentially the opposite direction, so of course some "attitude adjustment"
will be required. :-)  

The other good news is that the leak is apparently dumping overboard, with the
resulting thrust being applied along the spin axis--the propellant vapor is
unlikely to hang around and damage the spacecraft interior. 

Did anybody say which valve it was that was being exercized when the telemetry
stopped? I wonder if it is in the circuit for the propellant that is leaking? Is
it even known *which* propellant is leaking? Or if perhaps there was a very
brief pulse of hypergolic mixing of leaked propellants in the engine at that
time? 

Da goil's got nuttin' but questions. :-) But we do learn a little more at a
time.

 73 de Maggie K3XS

-- 
-----/___.   _)   Margaret Stephanie Leber    / "The art of progress  /
----/(, /|  /| http://voicenet.com/~maggie   / consists of preserving/
---/   / | / |  _   _   _    `  _AOPA 925383/ order amid change and /
--/ ) /  |/  |_(_(_(_/_(_/__(__(/_  FN20hd / change amid order."   /
-/ (_/   '  K3XS  .-/ .-/    ARRL 39280   /___ --A.N.Whitehead ___/
/____ICQ 7161096_(_/_(_/__AMSAT 32844____/ <maggie@voicenet.com>
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