Lunar Module P57 Explanation

ThatRedMelon

New member
Joined
Apr 9, 2019
Messages
10
Reaction score
2
Points
3
Hello all,
I have been performing the Apollo 11 mission and have managed to land on the moon, but I am not certain about how to perform the P57 Lunar Surface Alignment using the AOT. I have tried looking at the Users' Guide to Apollo GN&CS Routines document but it doesn't greatly explain how to operate the AOT properly and perform the measurements to put inside the LGC. Does anyone have a good explanation or document that can aid me in performing this?
Thanks for all your help and the great simulation.
 

rcflyinghokie13

LM Junky
Addon Developer
Joined
Jun 4, 2016
Messages
112
Reaction score
18
Points
18
The P57 is certainly a unique animal! Here is a brief overview of the AOT that might help explain the cursor and spiral. https://www.hq.nasa.gov/alsj/aot.htm

Just like other alignments you have multiple options. I will use the REFSMMAT Option 3 with 2 celestial bodies as an example:

Just like a P52, basically aligns your platform based on the current stored REFSMMAT, so you need to mark 2 celestial bodies (stars in this case) and since you cannot point the AOT center at a star, you need to tell the computer where it is, this is the purpose of the cursor and spiral.

Entering the P57, you will choose option 3, and then the alignment technique (F 05 06) you will choose option 2 in R2.

From here you will get a F01 07 and you will be entering the star and AOT detent you plan to use. The flight plans usually will have ones preferred to use but you can designate your own as well. Each AOT detent is a number in the LGC (1-L 2-F 3-R 4-RR 5-CL 6-LR). We will use star 2 in the front detent in this example, so you will enter into R1 00202 (XXCDE, C being the detent, DE being the star code) and proceed.

You will then get a F 06 79 showing the "expected" positioning, here you proceed and get a F 01 71 and you reenter the detent and star code 00202. After entering and proceeding, you are met with a F54 71 indicating you can mark. Use the W and S keys to rotate the cursor line (the one with the "V" shape around it and position it over your chosen star. When you have it on the start you press mark (either x or y mark) and your LGC will display a F 06 79.

Now you need to load the cursor and spiral angles into the DSKY. R1 is cursor so you look at the AOT and there is a little number on the panel where you can see the detent type and mark buttons etc. This is in XXX.X degrees. You use that number and enter it into R1. Next you move the AOT again to place the star in the center of the spiral lines, read the number on the AOT, and enter it into R2. Lastly you verify or change R3 to the detent you are using (2 in this example). After al three are entered you will enter a V32 to recycle the program and repeat the procedure again 2 more times to have a total of 3 marks on the star.

After you make your last mark and entries in the LGC, you need to proceed to select a new star. You hit proceed and you will, like before, be met with a F01 70. From here you choose your second star and detent and follow the above steps again for 3 marks.

After you proceed on the second star marks, you will get, like in your P52, a F 06 05 showing the star angle difference. Low is good as in a P52. You proceed and get a F06 93 showing the gyro torque angles, and the rest is just like concluding a P52.

I know this was a bit long winded but I hope it at least helps steer in the right direction!
 

ThatRedMelon

New member
Joined
Apr 9, 2019
Messages
10
Reaction score
2
Points
3
Thank you so much! That explanation makes perfect sense! I'm always amazed at the details of this simulation. I'll be sure to join the discord server.
 
Top