Question Apollo 10 AGS Activation

riclourenco

Donator
Donator
Joined
Apr 11, 2018
Messages
44
Reaction score
0
Points
6
Location
Brejos de Azeitão
Hello!

I have been reading the AGS manual to do the activation. But there are some things that I still have doubts, and I would like to confirm if I did this procedure well. At GET 97h20 the time came in the checklist of "Set AGS Time (377) Biased" (AGC- V16 N65). I set the AGS time for the next minute:

CLR 377+04410 and hit Enter on the DEDA at Get 97h21 (for AGS zero time Get 90h00)

https://puu.sh/CbRjs/e69ddc60f2.png

Now this part is the question itself. Soon after this, the "Enter AGS Zero time" arrived in checklist (AGC- V06 N16 (90:00:00)). What I did was enter in DEDA the PAD data with the K-Factor given for the AGS activation:

CLR 224 +00000 Enter
CLR 225 +00000 Enter
CLR 226 +00000 Enter
CLR 227 +00000 Enter

https://puu.sh/CbRvg/cabcc6c71b.png

And then I continued the checklist. Is this procedure correct? Is this the way we tell the AGS that “Zero time” is the GET 90h00:00 that is in V06 N16 AGC display?
Another question is the fact that I do my undocking 20 minutes later than the expected GET (98h10). I can only do undocking on GET+- 98h30, but I already know that there is no problem, and was even normal in the Apollo 10 mission. But regarding the CSM burn separation on Get 98h51, if I cannot finish the checklist in time to do this burn, is there a problem if I load a different TIG in CSM AGC? Tig- 99h05:00 for example?

https://puu.sh/Cb0hv/3cd1cdd17f.png

Thanks!
 

indy91

Addon Developer
Addon Developer
Joined
Oct 26, 2011
Messages
1,113
Reaction score
400
Points
98
Hello!

I have been reading the AGS manual to do the activation. But there are some things that I still have doubts, and I would like to confirm if I did this procedure well. At GET 97h20 the time came in the checklist of "Set AGS Time (377) Biased" (AGC- V16 N65). I set the AGS time for the next minute:

CLR 377+04410 and hit Enter on the DEDA at Get 97h21 (for AGS zero time Get 90h00)

https://puu.sh/CbRjs/e69ddc60f2.png

This is all correct.

Now this part is the question itself. Soon after this, the "Enter AGS Zero time" arrived in checklist (AGC- V06 N16 (90:00:00)). What I did was enter in DEDA the PAD data with the K-Factor given for the AGS activation:

CLR 224 +00000 Enter
CLR 225 +00000 Enter
CLR 226 +00000 Enter
CLR 227 +00000 Enter

https://puu.sh/CbRvg/cabcc6c71b.png

And then I continued the checklist. Is this procedure correct? Is this the way we tell the AGS that “Zero time” is the GET 90h00:00 that is in V06 N16 AGC display?

When you first enter the AEA clock time it's a manual procedure that might not be very accurate, especially because V16 N65 only updates once a second. MCC-H then would look at telemetry to figure out when the enter was actually pressed on the DEDA and gives the astronauts a corrected K-factor to enter in V47. This will not be exactly 90:00:00 because the enter press wasn't accurate to 0.01 seconds, obviously. This number will then be read up to the astronauts. On Apollo 10 it was:

097:05:37 Duke: Roger. 090 00 03 00.

So 3 seconds off (how did they manage that, haha). Usually it was within a second. Unfortunately we haven't figured out yet how mission control was able to determine the exact K-factor. The AEA doesn't update the internal clock like the AGC. And even if we figure it out, making compatible with the MCC in NASSP might be difficult, because it might have to look at the AGS telemetry stream. In any case, for the MCC PADs I've just left the K-factor to the nominal time (in this case 90h GET), which will already have been loaded in the LGC.

The addresses 224 to 227 actually don't have anything to do with the AEA clock time. They are for descent abort constants, they just share a PAD (or data card rather) in the flight documentation of later Apollo missions and I have reused it for Apollo 10 until we find the actual PADs and activation checklist for that mission. Of course the descent abort constants are not applicable for Apollo 10 so it doesn't matter if you enter them on the DEDA or not.

So the procedure is different than for LGC clock initialization. The AEA doesn't have a V55, instead they left the clock running as initially entered and slightly modified the AEA reference time, which is the K-factor.

Another question is the fact that I do my undocking 20 minutes later than the expected GET (98h10). I can only do undocking on GET+- 98h30, but I already know that there is no problem, and was even normal in the Apollo 10 mission. But regarding the CSM burn separation on Get 98h51, if I cannot finish the checklist in time to do this burn, is there a problem if I load a different TIG in CSM AGC? Tig- 99h05:00 for example?

https://puu.sh/Cb0hv/3cd1cdd17f.png

No, the separation maneuver really shouldn't be moved. If anything you should be undocking earlier if you are short of time. The separation and DOI times are fixed times calculated backwards from the intended PDI point. Undocking on the other hand is more flexible. You should be undocking 25 minutes before the sep maneuver, as in the flight plan, so it seems you stole yourself about 5 minutes if you want to do undocking at 98:30. Do it a few minutes earlier instead, 98:26 maybe.
 

riclourenco

Donator
Donator
Joined
Apr 11, 2018
Messages
44
Reaction score
0
Points
6
Location
Brejos de Azeitão
Hello

OK thank you very much! So what should I do when "Enter AGS Zero Time" arrives at the checklist? Should I make CLR 377 + 0xxx0 for the next minute again?and should I always do this when later arrives again in the checklist? Or should I simply do on the AGC with the V06 N16; V25E and load the AGS zero time there?

R1 = + 00090
R2 = + 00000
R3 = + 00000

Although this is already on the AGC display as soon as we load V06 N16.

And in the case of Apollo10 the Pad with K-Factor:

AGS ACTIVATION
90: 00: 00.00 GET
  224 +00000
  225 +00000
  226 +00000
  227 +00000

In this Print: https://puu.sh/CbRvg/cabcc6c71b.png

Not used in Apollo 10 then? I thought it was related to the AEA clock time because it is referenced with GET 90: 00: 00.00 (which is AGS zero time) and says "AGS activation". So if it's not used in Apollo10, it should be used in apollo11, I suppose, and the values should not be zero, probably (since they are for descent abort constants, as you say). Am I correct now?

Thanks for your help
 
Last edited:

indy91

Addon Developer
Addon Developer
Joined
Oct 26, 2011
Messages
1,113
Reaction score
400
Points
98
Hello

OK thank you very much! So what should I do when "Enter AGS Zero Time" arrives at the checklist? Should I make CLR 377 + 0xxx0 for the next minute again?and should I always do this when later arrives again in the checklist? Or should I simply do on the AGC with the V06 N16; V25E and load the AGS zero time there?

R1 = + 00090
R2 = + 00000
R3 = + 00000

Although this is already on the AGC display as soon as we load V06 N16.

You don't have to do anything here I think. Certainly not the 377+XXXXX procedure again. In reality they would have changed N16 when it gets displayed in V47. But it's always going to be identical with what already preloaded, at least until we figure out how mission control calculated the new K-Factor. So at some point in the future the PAD value might differ from the preloaded one and N16 should be changed.

And in the case of Apollo10 the Pad with K-Factor:

AGS ACTIVATION
90: 00: 00.00 GET
  224 +00000
  225 +00000
  226 +00000
  227 +00000

In this Print: https://puu.sh/CbRvg/cabcc6c71b.png

Not used in Apollo 10 then? I thought it was related to the AEA clock time because it is referenced with GET 90: 00: 00.00 (which is AGS zero time) and says "AGS activation". So if it's not used in Apollo10, it should be used in apollo11, I suppose, and the values should not be zero, probably (since they are for descent abort constants, as you say). Am I correct now?

Thanks for your help

On Apollo 11 and later 224 to 227 won't be zero, yeah. They are just zero here because it's not necessary to enter anything. It rather should say N/A, not applicable, I guess. But it doesn't matter what value is loaded for them on Apollo 10. Just leave them as they are.

The K-Factor and descent abort constants were usually read up to the crew as part of a AGS activation update, like here: https://www.hq.nasa.gov/alsj/a13/A13LMDataCardBook.pdf PDF page 4 on the right side. This was certainly true for Apollo 12 and later. Unfortunately we are missing (most of) the Data Card Books and Activation Checklists for Apollo 10 and 11, so we can only guess which PAD form exactly was used to write certain things down. So for now the PAD is based on how it was done for later missions.
 

riclourenco

Donator
Donator
Joined
Apr 11, 2018
Messages
44
Reaction score
0
Points
6
Location
Brejos de Azeitão
Okay thank you very much, I think I am understanding now .. Because when we enter the AGS time with 377+0xxx0 on DEDA, we can not be accurate to 0.01 seconds or even to 0.10 seconds of course , the mission control after that gives us a K-factor, a new AGS zero time to load the LEM AGC to correct this imprecision, so that I instead of having:

R1 = + 00090
R2 = + 00000
R3 = + 00000

In V06 N16 of the LEM AGC, i have to load the new AGS zero time with the command V25 to:

R1 = + 00090
R2 = + 00000
R3 = + 00045

For example! In which it is not yet possible in NASSP to calculate this!So this means that I only have to do 377 + 0xxx0 in DEDA once, it does not make sense to repeat it again, since it will be inaccurate again. So it only can be accurate if mission control sends us the new AGS Zero Time GET to correct this! Am I right? :)

I will start the LEM again from the PNGS activation from the fixed save file that you sent me, since there is already NASSP-V8.0-Alpha-Orbiter2016-1350. I'll start from this new version, and practice more too.
 

indy91

Addon Developer
Addon Developer
Joined
Oct 26, 2011
Messages
1,113
Reaction score
400
Points
98
Yep, you got it right!
 

riclourenco

Donator
Donator
Joined
Apr 11, 2018
Messages
44
Reaction score
0
Points
6
Location
Brejos de Azeitão
Thank you very much for your great explanations and for your time once again indy91! I'm just thinking how NASA could calculate that new AGS Zero time ... :) :D

see you in orbit! :D

Best Regards
 
Last edited:
Top