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21

Apollo 13 Moments of Interest / 141:15:37 Jack Garman predicts LM jettison gimbal lock

« Last post by MadDogBV on August 30, 2024, 03:39:29 pm »

During the LM jettison, in a brief conversation with YAW Will Pressley, Jack Garman warns him that "transience in separation" might cause a CSM gimbal lock to occur. He's referring specifically to oscillations in attitude as a result of the delta-V imparted on the CSM in separation. The deadband isn't as much of a concern since the spacecraft is in a 5-degree deadband; thus, the middle gimbal angle is moving between 10 and 20 degrees from gimbal lock.

Later, one of the AGC support personnel calls the gimbal lock warning, but because his voice on the loop is so faint, it's missed and it's a full 3 or 4 seconds before anyone from the ground brings this to the attention of FLIGHT/CAPCOM. By that point, it's already too late and Swigert has already gone to direct control to correct this, but Garman does take this as an opportunity to remind Pressley of his concerns.

Link:
Before gimbal lock - https://apolloinrealtime.org/13/?t=141:15:37&ch=22
Gimbal lock - https://apolloinrealtime.org/13/?t=141:30:14&ch=22

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Apollo 13 Moments of Interest / 141:02:53 Reed: "I'm gonna jam him back in!" Panic over Lovell's wrong turn

« Last post by MadDogBV on August 30, 2024, 03:11:05 pm »

In "13 More Things That Saved Apollo 13", it notes that Jim Lovell put the Apollo 13 spacecraft 90 degrees out of the desired jettison attitude (LM yaw, CSM/body roll), since LM yaw was an out-of-plane orientation and going to the PAD attitude would have put the spacecraft in gimbal lock. In looking at the air-to-ground and PAO loop, there is no indication that there's any issue with this, as CAPCOM Joe Kerwin reassures Lovell that the yaw isn't critical.

In the trench, it's a much different story.

After Swigert's fantastic P52 which bypassed the need for a sun-moon alignment, there was a frantic effort by both the ground and the crew to get the LM jettisoned. As a result, Kranz never got a formal "go" from GUIDO Ken Russell for the jettison attitude. In the chaos, the "go" came from CONTROL Hal Loden, which created a stir in the trench. GUIDO pointed this out to FIDO Dave Reed and warned him that CDR Jim Lovell was bailing out of the LM, per the air-to-ground. Reed made a remark that would have been unthinkable coming from any other FIDO: "I'm gonna jam him (Lovell) back in!"

What follows is a very confused series of events, and it really benefits to listen to the whole loop from 141:02 to 141:10, as it progresses from the trench bickering and arguing over the safety of the jettison attitude (the normally cool and professional Dave Reed audibly vacillates on whether the attitude is safe), with FAO and CONTROL jumping in to provide their input. In the end, the question is brought to FLIGHT, Gene Kranz, with the eventual determination that they have no choice but to accept the new jettison attitude. Either way, this is arguably the moment of greatest panic throughout the entry prep for the Trench.

FIDO: We need to have Jim take the LM to the FDAI angles that we gave him on the LM jettison pad!
FLIGHT: How far off is he?
RETRO: Flight--he's gonna jettison the service module to the north--I mean, the LM to the north. We don't want him to the north, we want him to the south.

One thing of note about this exchange is that Kerwin asks if the concern is about the impact on the landing point of the atomic fuel cask (as mentioned in the article), but RETRO Chuck Deiterich explains, as he does in the article, that they simply want to ensure that the LM and CSM don't collide in the jettison. This is supported by the fact that Dave Reed later checks the relative motion of both spacecrafts with the new attitude, and verifies that both will be okay.

Link:
FIDO - https://apolloinrealtime.org/13/?t=141:02:53&ch=20
GUIDO - https://apolloinrealtime.org/13/?t=141:02:53&ch=21
CONTROL - https://apolloinrealtime.org/13/?t=141:02:53&ch=57

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Apollo 13 Moments of Interest / Re: 072:05:17 - Woman's voice

« Last post by zootboy on August 03, 2024, 03:09:16 pm »

Some additional discussion about the source of the issue on NETWORK:

https://apolloinrealtime.org/13/?t=072:10:20&ch=11

https://apolloinrealtime.org/13/?t=072:16:41&ch=11

Mention of a patching issue in the Madrid microwave link, and the fact that they switched to an alternate channel while they monitor the original channel to see if the crosstalk reappears.

24

General Discussion / Re: Other Apollo Missions

« Last post by Kasper on July 31, 2024, 08:47:42 am »

Any Apollo 16 update? Or is it never going to happen?

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Apollo 13 Moments of Interest / 126:41:26 Jack Garman agitated over Mattingly veering off script

« Last post by MadDogBV on July 26, 2024, 06:51:06 am »

During the read-up of the CSM entry checklist to Jack Swigert, Ken Mattingly deviates from the checklist momentarily to talk to Jack Swigert about how to bring the computer out of standby.

AGC specialist Jack Garman, who had already been grousing with Steve Bales earlier in the day about ensuring that the computer procedures were properly detailed, explodes with exasperation upon hearing this, as he believes that Swigert is being fed incorrect information. Even Swigert himself seems to sound confused; as Garman explains to Bales, since the computer would have been powered up for a while by this time and would have already gone to standby, the 37 06 would not come up automatically as Mattingly is claiming.

Later, Garman stalwartly predicts that Swigert is going to get to this point in the checklist and then call down to Houston with a complaint that the computer doesn't work.

Garman later turns out to be correct.

URL: https://apolloinrealtime.org/13/?t=126:41:26&ch=22

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Apollo 13 Moments of Interest / Re: 107:05:24 Exasperated FIDO and RETRO grill CONTROL on SHe tank

« Last post by MadDogBV on July 11, 2024, 07:43:12 am »

A follow-up post for those who were interested in the actual nitty-gritties of how the flight controllers were planning to mitigate the SHe problem. Here's a briefing from Jay Greene to the SELECT on duty (John "Al" Layton) at 107:45 GET:

Link: https://apolloinrealtime.org/13/?t=107:45:53&ch=20

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Apollo 13 Moments of Interest / 055:06:23 EECOM Liebergot reveals how high-gain antenna failed

« Last post by MadDogBV on July 04, 2024, 09:17:25 am »

A serious amount of documentation (available here on page 118 of the PDF, and here as a separate document) was churned out by the Test Division in trying to figure out why the high-gain antenna failed to lock up with the Apollo 13 spacecraft during the TV pass at 55 hours. In both documents, the specific cause of the antenna failure was not fully identified, although it did note that it was not a manufacturing defect and that the failure likely occurred after transportation from the manufacturing plant.

EECOM Sy Liebergot, listening in to INCO struggling to lock up the high-gain with the spacecraft, calls up the EPS personnel in his backroom to let them know how the high-gain antenna may have been broken - and it's a surprisingly simple explanation.

Even during the Apollo program, accidents did happen!

Link: https://apolloinrealtime.org/13/?t=055:06:23&ch=16

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Apollo 13 Moments of Interest / 064:16:26 Bob Carlton gives the redline for power and water

« Last post by MadDogBV on July 04, 2024, 08:44:02 am »

During a briefing session by FLIGHT Glynn Lunney on the Black Team shift immediately following the accident, off-duty CONTROL Bob Carlton joins the conversation to give the MOCR flight controllers, and not incidentally Glynn himself, the straight talk on just how austere a power/water profile they will need to adhere to in order to get the crew home safely. This chilling opening dialogue really drives home just how grim the situation was:

CONTROL: Glenn, the guys in the back are running this water profile. Right now it looks like it's coming in real tight, the water itself.
FLIGHT: Yeah? Assuming we stay at this level from now on?
CONTROL: Negative. Assuming we power down post PC2.

Link: https://apolloinrealtime.org/13/?t=064:16:26&ch=50

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Apollo 13 Moments of Interest / 019:19:14 BOOSTER reports to FIDO Greene that S-IVB is tumbling out of control

« Last post by MadDogBV on July 04, 2024, 08:13:12 am »

The BOOSTER engineer (as yet unnamed) reports to a bemused FIDO Jay Greene that it's no longer possible to command to the S-IVB to change its trajectory, and both the guidance platform and computer on board have broken down. He delivers this with report with a demeanor not unlike that of someone whose car has just broken down for the last time.

Later, he reports this to SELECT who is already having difficulty calculating its trajectory due to the noisy Doppler data. They're even more thrilled to discover that the APS (ascent propulsion system) thrusters are still firing and producing rates.

Link: https://apolloinrealtime.org/13/?t=019:19:14&ch=20

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Apollo 13 Moments of Interest / 107:05:24 Exasperated FIDO and RETRO grill CONTROL on SHe tank

« Last post by MadDogBV on June 17, 2024, 08:40:27 am »

CONTROL Larry Strimple is working his second mission in the MOCR after having been backroom support in the LM SSR for several missions. Maroon Flight Milt Windler has just floated the very, very undesirable prospect over the flight loop of having to periodically (every hour on the hour) fire a 10-second ullage of the DPS in order to alleviate the supercritical helium tank. Obviously, this would wreak havoc on the spacecraft's trajectory, since Aquarius is currently on what is essentially a free-return trajectory with no PGNS, no AGS, and very little tracking data.

It seems CONTROL isn't as worried about this as the rest of the flight controllers are, as FIDO Bill Boone and RETRO Tom Weichel give Larry a taste of just how hard it is to be a flight controller during an anomaly situation.

Link: https://apolloinrealtime.org/13/?t=107:05:24&ch=20