Re: [amsat-bb] AO-40: Wheel tests Orbit 365

[ahelmfelt@xxxxxxxxxxxx]

Hi...

Check the http://www.amsat-dl.org/journal/adlj-p3d.htm

There is a nice job with the general status that now will change the 
whell icon.

best regards.

Alberto LU2FGN

www.sateliteros.com.ar



At 11:48 PM 16/08/2001 -0000, you wrote:
>What activities remain to be done in order to complete commissioning of
>AO-40?
>
>----- Original Message -----
>From: Peter Guelzow <peter.guelzow@arcormail.de>
>To: <amsat-bb@AMSAT.Org>; <info@amsat-dl.org>
>Sent: Thursday, August 16, 2001 9:40 PM
>Subject: [amsat-bb] AO-40: Wheel tests Orbit 365
>
>
>> Dear All,
>>
>> Stacey Mills W4SM and James Miller G3RUH conducted another wheel session
>> last night in Orbit #365 and the resulting calculations below were
>provided
>> by Karl Meinzer DJ4ZC.
>>
>> The wheels were spun up to +100 RPM. This was accomplished with quick
>> lock on all three wheels. They were left at this speed for ~30 minutes.
>> Telemetry before and after the spin-up, once the solar sensors re-locked
>> showed:
>>
>>     2.65222 +/- 0.00002 RPM baseline
>>     2.61468 +/- 0.00004 RPM after spin up to +100 RPM
>>    ----------
>>    -0.0375 RPM (for +100 RPM on wheels)
>>
>>
>> If all was done correctly in the s/c - and the above data bear this out -
>> the positive spin is counted in the same direction as the z-axis. Thus
>> by positively rotating the wheels, momentum is in the same direction as
>> the s/c spin. Since the total angular momentum is conserved, the s/c
>> spin must decrease, which it did. Good!
>>
>> Now some data of the wheels:
>>
>> Izz    = 54.6*10^-3 kgm^2
>> Tmotor = 29.0*10^-3 Nm   at 25 rad/s
>>
>> The 3 wheels as a consequence of the mounting geometry produce an
>effective
>> Iz as seen by the s/c (if operated with equal rpm):
>>
>> Iz(3wheels) = Izz * SQR(3) = 94.57*10^-3 kgm^2
>>
>> Thus the test with 100 rpm or 10.472 rad/s put a momentum of 0.9903 Nm
>into
>> the axis parallel to the s/c z-axis, the other components cancel.
>>
>> With the above delta of -0.0375 rpm or -3.927*10^-3 rad/s this results in
>a
>> s/c Izz of 252.19 kgm^2
>>            ============
>>
>> With the very accurate figure of the spacecraft Izz, we hope to have
>sufficient
>> data to deduce from this figure the state of our fuel-tanks.
>>
>>
>> We can say with some caution that we have a working 3-axis control
>system!!!
>>
>> More tests will be done over the next few weeks, before we will transfer
>the
>> spacecraft from spin stabilization into 3-axis stabilization.
>>
>>
>> 73s Peter DB2OS for the AO-40 Team
>>
>> ----
>> 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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