Meadville Space Center

Project Apollo - NASSP => Support & Bugs => Topic started by: bertog on March 21, 2007, 04:39:06 AM



Title: P52 Question ...
Post by: bertog on March 21, 2007, 04:39:06 AM
Hi all,

Last night I've try using the EOCA scenario provide by Christophe some P52 using the preferred option and the Ops3 REFSMMAT.

Everything is working well, but when the CMC drive optics to find the select star I found it orizzontally match the cross in the SCT but vertically placed at the top of the SCT.

I've centered with the SCT and mark the star using SXT.

The result of the two star mark is a poor +01598  :oops:

This mean the the IMU is out of his alignment or that I've made something wrong in the mark procedure ?

How to realing the IMU in the best way ?


Title: Re: P52 Question ...
Post by: Christophe on March 21, 2007, 05:29:39 AM
Hmmm probably something wrong in the mark procedure. The sequence is a bit confused while running P52. By the past it happened to me to do some mistake with the star ID code. After the mark I remember you're asked to confirm the latest star used and not to enter the next one. I did that mistake very often at the beginning and of course the result was wrong.
May be you did something like this?


Title: Re: P52 Question ...
Post by: bertog on March 21, 2007, 05:39:37 AM
Could you confirm that this sequence is right ?

After marking the star

F50 25
00016

PRO

F01 71
[Same Star Code as the previous F01 70]
PRO

F01 70
[Second Star Code]
PRO

And it begin the second mark sequence ...

It's Ok ?





Title: Re: P52 Question ...
Post by: Tschachim on March 21, 2007, 12:07:49 PM
Look here: http://nassp.sf.net/wiki/IMU_Realign_checklist_%28Virtual_AGC%29

... and someone just added a strange comment about :? "PROing the options" :? to this article, which seems to be wrong, at least I don't understand it. I reverted the edit, but if the guy is around here I would be interested in what was meant by the comment and to resolve the issue...

Cheers
Tschachim



Title: Re: P52 Question ...
Post by: Tschachim on March 21, 2007, 07:14:13 PM
Last night I've try using the EOCA scenario provide by Christophe some P52 using the preferred option and the Ops3 REFSMMAT.

I did that, too. The first automatic navigation star was 32, the attached screenshot shows the expected position. The IMU is quite misaligned, about 1-2 in each axis. Christophe, I really suggest to take a look at the latest beta and Apollo 7, which has really the better pad load (especially the ephemerides) and to do a P52 as soon as you reached orbit.

I'm still working towards my first EOCA burn soon, the excel is really great!  :)

Cheers
Tschachim


Title: Re: P52 Question ...
Post by: Christophe on March 22, 2007, 05:37:34 AM
Thanks Tschachim.
In fact I worked tonight on the init page (which will renamed as <Config & Init>) of the EOCA to allow the user to put in the state vector and MJD of his own favorite scenario.
That would definitely solve the test scn trouble.
Hope I can post a new beta before tomorrow afternoon cause I' m on duty ( :() this weekend from friday to monday.


Title: Re: P52 Question ...
Post by: bertog on March 23, 2007, 04:55:20 AM
The last question ...

How is possible to recover this bad IMU ? Is needed to update the REFSMMAT it self or via the P52 is possible to realign the IMU ?


Title: Re: P52 Question ...
Post by: Tschachim on March 23, 2007, 05:07:38 AM
You can realign the IMU by using P52, option 3.

Cheers
Tschachim