Re: [amsat-bb] Re: ArcJet Update

["MCGWIER ROBERT" <rwmcgwier@xxxxxxxx>]

With the lower perigee (before NH3 dump),  we would have
had a much more difficult time with the momentum wheels.
The constant addition of rotational momentum due to the
drag at the low perigee would have necessitated a great
deal more magnetorque maneuvers to dump excess
wheel RPM's.   We definitely gained in operational
stability, if not in orbital stability with this maneuver.

Bob


----- Original Message -----
From: "Peter Guelzow" <peter.guelzow@arcormail.de>
To: <amsat-bb@AMSAT.Org>; <forum@amsat-dl.org>
Sent: Monday, July 09, 2001 5:08 PM
Subject: [amsat-bb] Re: ArcJet Update


> Dear All,
>
> I should add a few points to Stacey's excellent summary.
>
>
> What did the users missed?  Nothing...  There would not have been
> enough ammonia for a significant change in inclination. Perhaps we
> could have made 10-20° in inclination change, but than we would
> periodically have bad coverage due to the precessing orbit, with
> the apogee being over the wrong hemisphere (from either point of view)
> for some time...  Instead we could have reduced the apogee height
> making it a 16h orbit, but this also makes not such a big deal at
> the low inclination and the pathloss also does not really get much
> better..  so what?
>
> Indeed, it is very disappointing that we could not demonstrate the
> Arcjet burning "hot". On the other hand, ATOS has never flown before
> and it is highly experimental and rocket science. At least we learned
> that this type of TFMC (mass flow controller) is not flight worthy..
> Something which could not have simulated on ground..
>
> To be honest, we were not even sure if the Arcjet motor was still
> there..  You all heard the speculations that the bottom plate was
> blown away.. Obviously at least the motor was still there at the
> right position and mounting angle... ;)
>
> > 7. What's going to break next?
> >     ---------------------------
>
> No risk, no fun?
>
>
> > 8. And finally
> >     -----------
> >  We can withstand your critical scrutiny!   ...if
> > we can't we need a new hobby.
>
> Otherwise I wouldn't be here anymore, since I spent most of my life for
> it since AO-10.
>
>
> 73s Peter DB2OS
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