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Re: pt3 telemetry



Just a quick note...

There are no strain gauges on the tanks itself.  
The pressures are measured by discrete pressure transducers which
are part of the PFA module. While such a device could also
be damaged, it seems to be very unlikely.

73s Peter


MCGWIER ROBERT wrote:
> 
> I have noticed several people talking about the He pressure
> between burn attempts.  I am assuming you mean the high
> pressure side?   If so, you should know that we USED TO
> measure these pressures with strain gauges on the tanks,
> and I  <<presume>> we still do.   That being the case, I don't
> believe the number except as an indicator that a high value of
> pressure is still in the He bottle, not an accurate indicator of
> the exact pressure.  I believe it will tell us when it gets really low,
> so low that the regulator won't work properly (even if it EVER
> DID work properly under whatever fault condition is present).
> 
> As I stated, I believe we leaked propellant.   I believe this explains
> why the burn went long, why the regulator didn't regulate, why
> the electronic failures occurred, etc.  I don't think you should rely
> on the strain gauges except as "big picture" numbers if that
> is the kind of pressure indicator we are still using.  17.4 rpm,
> whew.  Has anyone published the moments of inertia as seen
> from (say) the momentum wheels or the magnetorqueing coils
> or for that matter, from any reasonable coordinate system in
> the bird?  We could do some ballpark estimates on what it
> would take to spin the bird up that much if we had these numbers.
> Then we could start guessing as to what could supply this
> angular momentum.
> 
> Bob
> 
> ----- Original Message -----
> From: "Richard D. Burgan" <wc8j@raex.com>
> To: "MCGWIER ROBERT" <rwmcgwier@home.com>
> Cc: <amsat-bb@AMSAT.Org>
> Sent: Thursday, January 04, 2001 8:58 PM
> Subject: Re: [amsat-bb] pt3 telemetry
> 
> > Hi All,
> > I had my first opportunity to hear AO-40 live early this morning.  I got
> up at
> > 3:30 AM (arghhhhh) and listened for about 45 minutes while the squint
> angle was
> > best.  I tried several things to lock onto the telemetry.  I got no good
> > blocks.  The amazing thing was how much doppler (?) frequency wobbling
> there
> > was.  My G3RUH modem was swinging 2/3 of the way across the tuning dial.
> Also
> > there is a slower fading of signal strength.  I am using a 20 dB loop Yagi
> > (linear polarization) so the fading might be due to some atmospheric
> rotation
> > effect.  I saw an AMSAT-BB post yesterday where Phil, KA9Q calculated the
> > doppler at +/- 14 Hz.  All the indications I had were that it is more than
> > that.  So there is something going on.  I roughly measured the rotation
> rate at
> > 17.4 rpm.  The sound that the speaker audio makes follows a repetitive
> pattern.
> > Put into a graph the frequency + noise follows a pattern like:
> >
> >  /^\                /^\
> > /    \_/^\_/^\_/    \_/^\_/^\ ...
> > <-3.44 Sec->
> >
> > I am curious about the following questions (among others):
> >
> >     1. How did the spin rate get from 9 rpm to 17 rpm?  Where did the
> energy
> > come from?
> >
> >     2. What happened to lower the Helium pressure between burn attempts?
> >
> >     3. Do other stations here the same audio pattern?
> >
> >     4. How could we accurately measure the "doppler" wobble from AO-40?
> >
> >     5. What do the propellants do to wiring and other spacecraft structure
> if
> > they leak?
> >
> > Lets hope we get some more information soon!  That would be GOOD news.
> >
> > 73's de Rich @ WC8J
> >
> > ----
> >
> > MCGWIER ROBERT wrote:
> >
> > > Elio:
> > >
> > > We are all waiting with our breath held and our
> > > fingers crossed to see if we will ever be able
> > > to use the LIU and Propellant assembly again.
> > >
> > > Prediction: NO.  A propellant leak which has
> > > attacked various electronics (mostly wiring)
> > > is my current favorite scenario.  The command
> > > team has got to be REALLY careful, especially
> > > about turning things on in and around the
> > > areas they think are most likely effected.  After
> > > being really careful, and finding out what has
> > > been lost,  a plan as to what mission can be
> > > accomplished with what is left has to be
> > > concocted based on what is left.  Don't expect
> > > much in the way of pronouncements until
> > > they have a really good idea on all aspects.
> > > This is understandable.  If there is a major
> > > loss of mission in the offing,  they would want
> > > to understand the total loss and what can be
> > > accomplished before listening to people
> > > in the gallery (like me) telling them what to do. ;-).
> > >
> > > Bob
> > >
> > > ----- Original Message -----
> > > From: "elio sequino" <elioseq@libero.it>
> > > To: <amsat-bb@AMSAT.Org>
> > > Sent: Thursday, January 04, 2001 2:05 AM
> > > Subject: [amsat-bb] pt3 telemetry
> > >
> > > > I have downloaded the pt3 telemetry file of the satellite AO-40 from
> the
> > > > amsat web site. Using the pt3 program with this file in replay mode,
> in
> > > the
> > > > navigation window we can't read the value of  the LIU/SP DEPLOY of the
> 400
> > > N
> > > > motor and the EPU value of the arcjet motor.
> > > >
> > > > Today  04/jan/2001 i am interested to know the value of  Hipres ,
> Lowpres
> > > > and the Valve position of the LIU .
> > > >
> > > > How can i do to read the LIU values with the pt3 program ?
> > > >
> > > > 73 de Ik8ppy Elio
> > > >
> > > > ----
> > > > Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
> > > > To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
> > > >
> > >
> > > ----
> > > Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
> > > To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
> >
> >
> 
> ----
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