Question Apollo 11- LM P57 align

riclourenco

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I'm doing the apollo11 mission and I've been able to land. Now I'm learning to do the alignment of the IMU on the surface (P57), which the first comes in get +-103h20:

https://puu.sh/CBVfS/eeae7ea95c.png

I read about it in this link:

https://www.hq.nasa.gov/alsj/aot.ht...Cx9haPJ944KnIPo_89rMZ1ikp9cuV8nOz2zvk0TK0kEQg

I think I've already made a good alignment. But I still have some doubts. Initially the AGC gives me R1=00546, which corresponds to the dentent CL, and 46 to the Sun, and it does not work. Is this normal?

https://puu.sh/CBVkw/8ed8931206.png

I must mark three times each of two stars I chose. The first mark I do on the Y-axis in the detent and Cursor angle that AGC gives me .After I chose a good star and detent, normaly the AGC gives me the same star in another detent:

https://puu.sh/CBVwS/2db0539135.png

https://puu.sh/CBVGl/f8d978340f.png

https://puu.sh/CBVI8/0dc37de6f9.png

https://puu.sh/CBVM2/3570e44ec2.png

https://puu.sh/CBVNw/3d5240bfe3.png


Then I adjust the Y axis precisely, and mark. Then I load the new Cursor angle on the AGC (R1).

https://puu.sh/CBVSc/1531ed0ba0.png

https://puu.sh/CBVTc/8109592ec0.png

Then comes the V32E Recycle, and I have to make the 2º mark. What I do is repeat the previous procedure by marking the Y-axis again.

https://puu.sh/CBVW3/f1f9229c69.png

https://puu.sh/CBVYe/1314b09d4d.png

Then when the V32 Recycle comes, I rotate the AOT to the of the spiral angle in R2, I ajust the spiral precisely to the star an Mark for the 3º time. Then I load the new angle of the spiral in the AGC (R2).

https://puu.sh/CBVZ9/55cc737904.png

https://puu.sh/CBW2u/ece30abab3.png

https://puu.sh/CBW5P/3a70764dfc.png

https://puu.sh/CBW7o/7e4191c666.png

Then I do the same for second star I can find, that is accepted by the AGC.

https://puu.sh/CBWeK/69106d0eee.png

https://puu.sh/CBWqj/45d082a653.png

and so on….

Of all attempts, with this procedure I was able to get better values, at least I think so. Is this procedure correct?

https://puu.sh/CBWtv/fc908aaf34.png

https://puu.sh/CBWwA/d5a2874da9.png

https://puu.sh/CBWxo/12122d8137.png

https://puu.sh/CBWy3/fff2b6e9fa.png

In the surface alignment it is indifferent to mark with Q (X) or Y (Y), right?
I also noticed that some of the stars we chose to do the alignment, make the AGC PROG light to turn on, and also that works better with the stars that are in the detents 1 (L), 2 F), and 3 (R). Can you give me some help/tips?

Thanks
 
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indy91

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Here two resources that might help you:

Apollo 11 LM Lunar Surface Checklist
Apollo 11 LM G&N Dictionary

The correct procedure depends on the alignment technique, in your case it seems to be the "2x Celestial Bodies" technique, so marks on two stars. P57 can definitely be a bit confusing. And it doesn't help that they completely reworked the program for Apollo 15, so for those of us who have flown one of the later missions you have to learn it almost from scratch again, haha.

I think I've already made a good alignment. But I still have some doubts. Initially the AGC gives me R1=00546, which corresponds to the dentent CL, and 46 to the Sun, and it does not work. Is this normal?

Define "does not work". I'm surprised that the LGC gives you the sun to mark on, but in that case I would always manually change the star ID to something else. The LGC dosn't actually know the position of the Sun in a very high accuracy, not as good as the CMC at least, so marks on it can't be all that accurate either.

In the surface alignment it is indifferent to mark with Q (X) or Y (Y), right?

Yes, for Apollo 11 that is correct.

The Checklist MFD usually only has generic checklists and the Lunar Surface Checklist I linked above is quite detailed, it has step by step procedures. So I would just review the relevant section of that checklist to see if your procedure differs in any way from it. If you got +00002 star angle difference as a result then I would say you have done a pretty good P57. From reading your description I would say your P57 procedure is about correct.
 

riclourenco

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Thank you indy91! With this apollo 11 LM checklist you gave me is easier :). I already have from 15 too!
I think we can always conclude that any alignment is good when the star angle difference has a low value, like the one I had, right?
Regarding the next missions they still do not have MCC, right? We have to do the uplinks through Apollo RTCC MFD. Is there a PDF where I can learn to do this?

Thanks!
 
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indy91

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Regarding the next missions they still do not have MCC, right? We have to do the uplinks through Apollo RTCC MFD. Is there a PDF where I can learn to do this?

Yeah, there is no MCC support for Apollo 12+ yet and the won't be until NASSP 9 and later.

There is manual for the RTCC MFD at "Doc\Project Apollo - NASSP\Programmers Notes" but it hasn't been updated since the NASSP 7 release. So it will only be partially helpful. I haven't updated it yet because the MFD has been changing quite a bit in the last two years. But I think it won't change too much anymore for the NASSP 8 release, so I'll soon work on updating the manual.
 

riclourenco

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OK thank you! Any way I still have a lot to learn until I start these missions.
I Still want to try to finish Apollo 9 from where I stopped, after I finished this apollo 11. And then I will still repeat apollo 11. Eventually I'll end up trying Apollo 12 with Apollo RTCC MFD,and then I'll see how it goes . :)
Regarding the NASSP 8.0 updates, I have noticed that there havent been updates on the SOURCEFORGE website. The update website is still the same, right?
 

indy91

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We aren't really using Sourceforge anymore, but it still is getting the same updates as Github. I am seeing the latest commit to the Orbiter2016 branch on the Sourceforge page, so it looks like it's still working right. Our main development website is Github, here are the releases: https://github.com/dseagrav/NASSP/releases
 

meik84

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P57 is quite an intriguing programm, but it has it's gotchas (just my experiences):
- there's no PICAPAR, i.e. you have to choose the stars manually. What the LGC presents in the first V01N70 is more or less random and must not be taken as a recommendation. Same applies to the second star: you have to chose one by yourself, preferrably one that is as far away from the first one as possible.
- on the V06N79 after V54N71 you have to enter both cursor and spiral angles, not spiral angle -> V32 -> cursor. If you want to take more then one mark on the same star, enter both angles and then key V32E.
- the first N04 (gravity vector error) after the landing is always high; the LGC compares the last gravity vector with the measured one, but the last one derives from P68. P68 always assumes that the LM is standing perfectly upright, which is of course not the case, even in Orbiter.
- alignment method 2 offers the possibility to determine the coordinates of the landing site. Just key ENTR on V50N25. Note that this will only work when there has been a gravity vector measurement before, i.e. method 1 or 3. The precision is quite good, I get 0.1° or less difference to NASSP MFD on the second pass. The first one has to be bad, as it partially uses data from P68, i.e. from the average g routine and radar -and that's not as good as gravity measurements and star sightings.
- don't use P51 or P52 on the surface. Bad idea. Really...:embarrassed:
 

riclourenco

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The first alignments seem to have gone well. I already did the EVA and now lets see if I can take off from the moon! :)
Thank you very much indy91 and meik84 for your help and explanations!
 
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