A11 and the first P52 - maneuvers?

[kneecaps]

The first P52 for A11 around GET 00:50:00, to date I've only done this with whatever stars I could find....however I noticed that historically was done with stars 30 and 37.

Curiously I've repeatedly found that I cannot sight these stars without using the SIVB to manuver to sight these stars without exceeding allowed trunnion angles. (The trunnion angles exceed 90 degrees in the time frame of the P52 which is not permitted by P52 for sightings).

I also don't notice in the flight journal or mission reports any mention of SIVB maneuvers (Buzz mentions only SIVB at orb rate).

I don't see from the sources I've checked that any kind of clear mention of crew controlled attitude changes of the SIVB in parking orbit prior to TLI. The only thing I've found is a mention at
002:04:12 "Guidance to IU".

This could imply that the switch was sent to CMC (implying crew control over attitude) or it could just be calling out a check.

Before I scour the MCC audio loops does anybody have any thoughts how the historical stars would have been usable for P52 at this time without maneuvers? If maneuvers were in fact performed, if Orbiter is something 'out' with regards to this.

 

[indy91]

I very much doubt that they went to CMC control for the P52. Maybe you just have the timing a bit wrong, the mission report says the P52 was done at 0:48h GET, but in the transcript it is even a bit earlier, maybe 0:45. So if Collins let the computer decide which stars to use it probably was around 0:45. At that time stars 30 and 37 should be available.

 

[MrFickles]

According to AFJ transcripts, Apollo 11 peformed their P52 starting at approximately MET 00:44.

Looks to me that they acquired star 30 at ~00:45:02, and star 37 at ~00:46:45.

Using the historical times, and starting my P52 at MET 00:44, CMC was able to automatically acquire both star 30 and 37. I can also confirm that performing P52 at MET 00:50 as per the NASSP checklist puts both stars just out of range.

On a side note: I say the crew acquired stars 30 and 37 but according to the transcripts, it seems to me like they were absolutely winging it.
Collins reported being able to see Menkent through the telescope but not the sextant. He also couldn't tell whether he was looking at Nunki through the telescope, but there was a star in the sextant, so he just marked it. Despite that, they managed to get a star angle difference of 0.01.

 

[Thymo]

Honestly it doesn't really matter if you use the historical stars. I always let the CMC pick a pair and align to that.

 

[kneecaps]

Honestly it doesn't really matter if you use the historical stars. I always let the CMC pick a pair and align to that.

Exactly what I have always done...except for the first time when I tried historical stars, to my surprise I couldn't actually sight on them without manuvering with the SIVB ... As Indy points out, this looks to be a VERY tight timing issue.

The P52 is earlier then timelined in reality and Collins looks to be REALLY fast with his work. Judging by the timestamps on the audio he seems to site on both stars in a little over 60 seconds. I suspect with the optics joystick, physical switches and a real DSKY in reach you can be really fast. It's pretty impressive considering the Orb Rate rotation...I find chasing the moving star a challenge and have never done better than 00001 when the stars are moving

---------- Post added at 02:44 AM ---------- Previous post was at 02:40 AM ----------

According to AFJ transcripts, Apollo 11 peformed their P52 starting at approximately MET 00:44.

Looks to me that they acquired star 30 at ~00:45:02, and star 37 at ~00:46:45.

Using the historical times, and starting my P52 at MET 00:44, CMC was able to automatically acquire both star 30 and 37. I can also confirm that performing P52 at MET 00:50 as per the NASSP checklist puts both stars just out of range.

On a side note: I say the crew acquired stars 30 and 37 but according to the transcripts, it seems to me like they were absolutely winging it.
Collins reported being able to see Menkent through the telescope but not the sextant. He also couldn't tell whether he was looking at Nunki through the telescope, but there was a star in the sextant, so he just marked it. Despite that, they managed to get a star angle difference of 0.01.

Great input thanks.. Yes, in my case in reality I'm probably going the P52 always a little after 50..closer to 53. 30 and 37 are way out of reach by then it seems, 7 minutes later than historical.

I see now my notion that they may have maneuvered was a faulty first assumption. They clearly used whatever stars they could find at the time.

"Mystery" solved

 

[polaris149Tiberius]

I have questions about the historic Apollo 11 P52 that occurred after TLI at GET 005:35 (17 Regor, and 34 Atria) and the one with the same stars at GET 005:39. Has anyone done that platform alignment?

 

[rcflyinghokie]

I have questions about the historic Apollo 11 P52 that occurred after TLI at GET 005:35 (17 Regor, and 34 Atria) and the one with the same stars at GET 005:39. Has anyone done that platform alignment?

What's the question about it? We have done many platform alignments.

 

[polaris149Tiberius]

I'm curious about what happened after the S-IVB slingshot observation at that time period. Any attitude changes that were needed and what they did with regards to the navigation and attitude changes during that period.

1. Did they have to do an attitude change after observing the slingshot to perform P52 and then another attitude change for the optics alignment/CAL?

2. Is the optics CAL part of P52 or P23?

3. What was done at about GET 005:35:00 and 005:39:00 (P52 or P23) and did they require attitude changes?

4. At GET 006:00:00 or around that time, I get confused when listening to the audio starting from this time (GET 005:05:20) to GET 006:00:00 when they start talking about a bias that needs to be set to zero. The audio starts up on this site: https://apolloinrealtime.org/11/?t=005:08:20&ch=14 (Apollo 11 Real-Time Mission Experience)

My real concern is after changing attitude to view the S-IVB slingshot maneuver, what attitudes did they change to and is there a way I can emulate any attitude changes for AMSO Apollo 11 to point toward. My goal is to get AMSO newer users as well as myself to get into the groove of starting to understand this form of navigation.

I'm creating an AMSO tutorial that allows readers to do certain things that occurred during the flight that will hopefully give users that are not exactly ready for NASSP a chance to emulate the procedures and processes that happened while listening to the comms on that Real-Time Experience website. This would be helpful to me to provide my recommendations for attitude changes in my tutorial to emulate these calibrations and alignment procedures and to understand them myself.

Thanks in advance.

 

[rcflyinghokie]

1. Did they have to do an attitude change after observing the slingshot to perform P52 and then another attitude change for the optics alignment/CAL?

After observing the SIVB they performed P52, in all likelyhood they didnt have to maneuver to get good stars as most attitudes in cislunar space had an acceptable pair of stars.

2. Is the optics CAL part of P52 or P23?

P23

3. What was done at about GET 005:35:00 and 005:39:00 (P52 or P23) and did they require attitude changes?

P52 did not need an attitude change, P23 has an automaneuver component so it gives you the attitude and allows the computer to initiate a maneuver to the P23 attitude for the star/landmark/horizon chosen

4. At GET 006:00:00 or around that time, I get confused when listening to the audio starting from this time (GET 005:05:20) to GET 006:00:00 when they start talking about a bias that needs to be set to zero. The audio starts up on this site: https://apolloinrealtime.org/11/?t=005:08:20&ch=14 (Apollo 11 Real-Time Mission Experience)

yeah thats the trunnion bias, basically they calibrate the optics because heat/solar radiation can make slight changes to the optics "zero" position and this was biased to compensate for those changes. Optics calibration is part of the P23 procedures.

 

[polaris149Tiberius]

On:

#1... Do you know when they might have performed that P52. And if so, do you have information as to what two stars were used?

#2... Thank you. Do you know when they would have performed the P23 during that period after the observation? I see they have "tweked numbers" of their original P23 attitude of roll 346.5, pitch 345, yaw 7.8 to ensure that star 30 is in the field of view of the sextant. When would they have gone to this attitude in GET time please.

#3... Thank you.

#4... Thank you.

I appreciate all the great info you have given. And appreciate any further info you can give me on the time (GET) they did those P23 maneuvers.

 

[rcflyinghokie]

On:

#1... Do you know when they might have performed that P52. And if so, do you have information as to what two stars were used?

#2... Thank you. Do you know when they would have performed the P23 during that period after the observation? I see they have "tweked numbers" of their original P23 attitude of roll 346.5, pitch 345, yaw 7.8 to ensure that star 30 is in the field of view of the sextant. When would they have gone to this attitude in GET time please.

#3... Thank you.

#4... Thank you.

I appreciate all the great info you have given. And appreciate any further info you can give me on the time (GET) they did those P23 maneuvers.

The star pairs were almost always selected by the computer in P52. There were some rare cases that a star was obscured by the LM or otherwise not as visible and they could easily just mark another star in the vicinity if necessary.

Also all of those times are in the flight plan, including that P23 after SIVB observation which was about 6h GET.

 

[polaris149Tiberius]

Thank you.

#1. Can you direct me by chance to the correct document "Flight Plan" as you said with a page number so I may refer to your comment about the time for P23?

#2. At 004:32:46 The Guidance calls the Flight Director with this bit of information. This is before the slingshot maneuver and about 15 minutes after the extraction of the LM from the S-IVB.

004:32:46 GUIDANCE: "Flight, Guidance. He’s loaded up the P-30 properly. He’s now in P-40 and doing the auto maneuver."

Do you have any idea what auto maneuver Collins may be doing at this point? Is it the PTC? Or the beginnings of his attitude to view the slingshot? Or something else. Thanks in advance.

 

[rcflyinghokie]

Links were down for ipv6 but you can try and see if the flight plan link works here https://www.ibiblio.org/apollo/Documents/Apollo_11_Flight_Plan_HSK.pdf

If not I have other ways of sharing.

And the maneuver there was the maneuver to the evasive burn to get them away from the SIVB.

 

[polaris149Tiberius]

So in the space of time between GET 004:30:04.00 to GET 004:36:40.00, the bottom line is (I believe) the vehicle is already in an attitude of Roll 344.00, Pitch 344.00 , Yaw 11.00 at GET 004:17:03.00 or going to it just after LM ejection (004:32:46 GUIDANCE: "Flight, Guidance. He’s loaded up the P-30 properly. He’s now in P-40 and doing the auto maneuver.")

Then they want Collins to change attitude to Roll 2.50, Pitch 289.30, Yaw 357.00 to see the slingshot. (004:31:34 FAO: "The new numbers are roll 2.5, pitch 289.3, yaw 357.")

Then return to the new P52 variation of 344.00, 344.00, 11.00 numbers to Roll 346.50, Pitch 345.00, Yaw 7.8.00 so he can see Star 30 in the sextant
(004:35:27 FAO: "Ok, now he should return to the old numbers, which we have tweaked up to ensure that star 30 is in the field of view of the sextant."
004:35:36 FAO: "Those numbers are, Roll 346.5, Pitch 345, Yaw 7.8")

Then go to Roll 198.4, Pitch 130.5, Yaw 340.0 for his P23 attitude at 006:10:00.00.
(004:36:07 FAO: "His P23 attitude, which he goes to at GET 006:10:00.00."
004:36:11 FAO: "Roll 198.4, Pitch 130.5, Yaw 340.0.")

Does anyone concur with this after listening to this soundbite below or reading the transcripts from it here :

Apollo 11 in Real Time

A real-time interactive journey through the first landing on the Moon. Relive every moment as it occurred in 1969.

apolloinrealtime.org

(GET 004:30:04.00 to GET 004:36:40.00) (It's kind of confusing to me)

Transcripts:

004:30:04 FAO: Hey Flight looking at the slingshot, we’ve got new numbers from the pre-flight numbers, and if he goes to the new numbers to look at the slingshot, he’ll have to go back and make an extra maneuver to get in a P-23 attitude, the optics cal attitude.
004:30:19 FAO: So he has a choice of sticking with the pre-flight numbers and possibly not being able to see the slingshot or making an extra maneuver to get the slingshot in the hatch window.
004:30:30 Then returning to his old numbers for the optics calibration.
004:30:34 FLIGHT: Ok, what do you recommend?
004:30:39 FAO: I think we ought to save the gas. There’s a slight chance he can see it by moving up close to the window with the old numbers.
004:30:47 FAO: They differ by ah...and the pitch is the big difference.
004:30:52 FAO: 344 was the old number. The new pitch is 289, 290.
004:31:04 FLIGHT: Tow what?
004:31:04 FAO: 290
004:31:05 FAO: This slingshot observation is the thing that’s been in and out so many times.
004:31:13 FAO: Were we going to do it were we not going to do it.
004:31:18 FLIGHT: So what you’re saying you go to 290 to see it. You’re going to have to do another maneuver to get back to ah...
004:31:20 FAO:...to go back to your old numbers right.
004:31:24 Flight: He has 244 for P23?
004:31:25 FAO: 344. He also got to change all three numbers, not just the pitch.
004:31:32 FAO: The old numbers are 344, 344, 11.
004:31:34 FAO: The new numbers are roll 2.5, pitch 289.3, yaw 357.
004:31:43 FAO: So if he wants to look at it, he’ll have to go to those new numbers and then return to 344, 344, 11.

004:31:53 FLIGHT: Booster, Flight.
004:31:57 FLIGHT: What time does the slingshot occur?
004:32:07 BOOSTER: Anytime you give us the a go after the evasive maneuver nominally about 005:05:00.00


004:32:46 GUIDANCE: Flight, Guidance. He’s loaded up the P-30 properly. He’s now in P-40 and doing the auto maneuver.
...

004:34:24 FAO: Okay, then say return to Roll 346, Pitch 345, Yaw 8.
004:34:29 Gimbals Off
004:34:34 FAO: For P-52 and Optics Cal
...

004:34:39 CAPCOM: FAO, Capcom.
004:34:41 FAO: Go, Capcom.
004:34:42 CAPCOM: Hey, when you're through, would you give me a rundown on the angles...
004:34:47 CAPCOM: ...that we need to go to if we look at the slingshot and the set of angles that we need to go to if we don’t look at the slingshot?
004:34:54 FAO: Ok, you ready to do it now?
004:34:57 CAPCOM: Yeah, I guess so.
004:34:58 FAO: Okay, well, what the problem is, we’ve had something change here. So to look at the slingshot, you want to go to Roll 2.5, Pitch 289.3, Yaw 357.
...

004:35:17 FAO: That’s the middle of the hatch window, so it doesn’t have to be to the 10th.
004:35:26 CAPCOM: Ok, then what?
004:35:27 FAO: Ok, now he should return to the old numbers, which we have tweaked up to ensure that star 30 is in the field of view of the sextant.
004:35:36 FAO: Those numbers are, Roll 346.5, Pitch 345, Yaw 7.8
004:35:59 CAPCOM: Ok, then the P23 attitude is what now?
004:36:01 FAO: Ok, now he stays in this number I just gave you for this.
004:36:04 FAO: P52 and his optics cal.
004:36:07 FAO: His P23 attitude, which he goes to at GET 006:10:00.00
004:36:11 FAO: Roll 198.4, Pitch 130.5, Yaw 340.0.
004:36:16 CAPCOM: Ok now he has the P-23 attitudes pinned into his flight plan, does he not?
004:36:23 FAO: That’s affirmative.
004:36:24 FAO: He has his old slingshot attitudes also pending and inked in, and they were 344, 344, 11.
004:36:27 CAPCOM: Ok, now if he decides NOT to observe the slingshot, all he has to do is go right to this P-52 attitude, is that correct?
004:36:40 FAO: Yes, 346.5, 345.0, 007.8

 

[rcflyinghokie]

Not sure what you are asking? It pretty much explains the sequence there. They read up updated attitudes to use.

 

[polaris149Tiberius]

I was asking if my interpretation is correct of the above transcript. Thank you for your response. I will just go on the interpretation I have.