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Author
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Topic: When were the Apollo LM legs extended?
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Jurg Bolli
Member Posts: 994
From: Albuquerque, NM
Registered: Nov 2000
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posted 08-18-2003 12:32 PM
   
After watching the HBO series "From the Earth to the Moon" again I still have the following question: when EXACTLY was the landing gear of the LM extended? Was it right after extraction, right before PDI or when? Same line of thought: were the legs ever extended on Apollo 13? Any info is appreciated. |
heng44
Member Posts: 3413
From: Netherlands
Registered: Nov 2001
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posted 08-18-2003 02:02 PM
I believe the legs were extended after arriving in lunar orbit. And I believe that on Apollo 13 they were extended in order to free the descent engine for firing. |
spaceuk
Member Posts: 2113
From: Staffs, UK
Registered: Aug 2002
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posted 08-18-2003 02:12 PM
The LM legs were normally extended after the CSM/LM combo had performed succesful LOI.The legs were released fairly early on in the LM Activation Check List just prior to the LM undocking from the CSM in preparation for its DOI/PDI sequences. |
spaceuk
Member Posts: 2113
From: Staffs, UK
Registered: Aug 2002
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posted 08-18-2003 02:15 PM
Apollo 9 - of course - was an odd ball since it did a simulated lunar mission in earth orbit with CSM "Gumdrop" and LM "Spider". So, it deployed its legs in earth orbit! |
FFrench
Member Posts: 3165
From: San Diego
Registered: Feb 2002
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posted 01-27-2009 08:39 AM
Does anyone know, for the lunar landing missions and particularly for Apollo 11, when in the mission the LM legs were extended into their final position? I have read one article stating that they were left retracted until shortly after the astronauts entered lunar orbit. Thanks!!Editor's note: Threads merged.
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heng44
Member Posts: 3413
From: Netherlands
Registered: Nov 2001
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posted 01-27-2009 09:27 AM
That is my understanding also. |
Cliff Lentz
Member Posts: 655
From: Philadelphia, PA USA
Registered: Mar 2002
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posted 01-27-2009 01:13 PM
I've always heard that this was the case. My problem is that even though Jim Lovell and Dave Scott were technical advisors on the movie "Apollo 13", it clearly shows the legs extended in the re-creation. This was before they entered lunar orbit. The legs are definitely extended when the LM was jettisoned just before reentry. Was there something different about procedures for 13? |
FFrench
Member Posts: 3165
From: San Diego
Registered: Feb 2002
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posted 01-27-2009 01:41 PM
I did read in one source that 13 was different, as with the LM engine being the only viable one, the legs would otherwise have been distressingly close to the engine plume had they not been extended early.I wonder if there was any contingency for LM lifeboat use if the legs would not extend for some reason, as that could really have caused a problem with using that engine... |
Jay Chladek
Member Posts: 2272
From: Bellevue, NE, USA
Registered: Aug 2007
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posted 01-27-2009 02:35 PM
I have a feeling the reason for the leg extension in A13 had to do with activation of the thrusters. So they probably extended the legs to make sure there were no issues with that (and the main engine bell of course). Of course considering how quickly they powered up the LM on 13, probably either Jim or Freddo glanced at the checklist they were abreviating probably said "it might be a good idea to do this right now" and they went ahead and did it regardless of if it was necessary or not.Center of gravity (center of mass) issues are probably also a concern for flying a LM with the legs stowed in terms of its flight behaviour. To my knowledge, the legs are typically extended when both craft are still docked to verify that they unfold properly. If they don't, you can't exactly land. |
Lou Chinal
Member Posts: 1332
From: Staten Island, NY
Registered: Jun 2007
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posted 01-27-2009 02:45 PM
As I remember the legs were extended just before separation. They did a pirouette in front of the Command Module so that Collins could check that the legs were down and locked. Armstrong's comment was "The Eagle has wings". |
MCroft04
Member Posts: 1647
From: Smithfield, Me, USA
Registered: Mar 2005
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posted 01-27-2009 07:03 PM
So did Armstrong mean that the legs were extended when he stated "The Eagle has wings"? I thought he meant that the Eagle was undocked and flying on its own. |
Jurg Bolli
Member Posts: 994
From: Albuquerque, NM
Registered: Nov 2000
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posted 01-27-2009 07:49 PM
I found more stuff in "How Apollo flew to the Moon" on p. 222, the exact moment is still not clear to me but it was certainly part of getting the LM ready immediately prior to undocking. I have two different sources, one says that it was done after they closed the hatch to the CM, the other says before. |
John Charles
Member Posts: 342
From: Houston, Texas, USA
Registered: Jun 2004
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posted 01-27-2009 08:07 PM
quote:
Originally posted by Cliff Lentz:
My problem is that even though Jim Lovell and Dave Scott were technical advisors on the movie "Apollo 13"...
Technical advisors can only advise, but the director can ignore them if he wishes. Despite the presence of Lovell and Scott in the production, note that "Apollo 13" (arguably the best -- and most accurate -- space movie ever) showed: - the command module re-entering the atmosphere with its docking probe still in place (in reality, it was always removed before re-entry, to avoid fouling the parachutes, and usually -- except for Apollo 14 -- left inside the LM)(I really hope I am not mis-remembering the movie!!)
- no evidence of any docking ring, the mechanism that joined the CM to the LM -- its ratcheting and clunking sounds were heard, but it was visibly missing in the exterior views of the docking.
No need to list the many other technical "gotchas" of the movie. Extending the legs probably was not one of them. |
Blackarrow
Member Posts: 3160
From: Belfast, United Kingdom
Registered: Feb 2002
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posted 02-02-2009 09:34 PM
quote:
Originally posted by FFrench:
Does anyone know, for the lunar landing missions and particularly for Apollo 11, when in the mission the LM legs were extended into their final position? I have read one article stating that they were left retracted until shortly after the astronauts entered lunar orbit. Thanks!!
According to "APOLLO: The Definitive Sourcebook" by Orloff and Harland, the landing legs of "Snoopy" on Apollo 10 were extended at 98:00 GET (11m 57s before CSM/LM undocking.) The information is not given for Apollo 11 or later missions, but was probably included as part of the LM check-out prior to undocking. |
WAWalsh
Member Posts: 809
From: Cortlandt Manor, NY
Registered: May 2000
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posted 02-04-2009 12:56 PM
Because someone needed to sift through the transcript. - At 04:02:27:07, the LMP reported that the LM had completed gear extension.
- At 04:02:44:??, Mission control asked for confirmation, and received it, that the landing gear was extended. This happened as the crew reached RCS pressurization for Eagle in the checklist.
- The start of the extension of the gear may have taken place during LOS on the dark side. The Apollo 11 On Board Voice Transcript notes landing gear deployed at 04:02:14:35.
All of this is from the three transcripts here.As a side note, the process may have changed for the final four lunar missions. The start of the first transcript in the lunar surface journal for Apollo 11 contains the following note: "Beginning with Apollo 14, the sequence of orbital procedures was modified so that the DOI burn was performed with the CSM Service Propulsion engine prior to LM separation. This change preserved LM fuel." I cannot see how this would have any direct impact, but it still might alter the checklist. |
FFrench
Member Posts: 3165
From: San Diego
Registered: Feb 2002
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posted 02-05-2009 02:07 PM
Thanks so much for taking the time to do this research! |
ilbasso
Member Posts: 1522
From: Greensboro, NC USA
Registered: Feb 2006
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posted 02-05-2009 04:01 PM
Yes, this was fascinating, and so much more useful than my initial thought, which was, "They were extended at some time prior to landing." |
Lou Chinal
Member Posts: 1332
From: Staten Island, NY
Registered: Jun 2007
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posted 02-06-2009 04:31 PM
John, you're right!I recall that Stu Roosa was told to find a place to stow the docking probe in the CM on Apollo 14. I believe the probe was flown again on another mission, but I can't remember which. |
Mike Dixon
Member Posts: 1428
From: Kew, Victoria, Australia
Registered: May 2003
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posted 02-06-2009 05:52 PM
It was flown again... and I think on Apollo 16.I remember seeing a press photo with John Young inspecting the probe following its return on Apollo 14. |
Proponent
Member Posts: 59
From: London
Registered: Oct 2008
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posted 02-09-2009 06:00 AM
Why would the probe have been re-used? Would not a probe have already been manufactured for Apollo 16? |
ilbasso
Member Posts: 1522
From: Greensboro, NC USA
Registered: Feb 2006
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posted 02-09-2009 08:33 AM
Toward the end of the Apollo program, a lot of parts were reused from one mission to another to cut costs, all the way from individual switches to control panels. |
Mike Dixon
Member Posts: 1428
From: Kew, Victoria, Australia
Registered: May 2003
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posted 02-09-2009 04:40 PM
Searching online proved fruitless in determining which subsequent mission used the probe... but I have a vague memory that after it had been cleared for flight (so to speak) the docking gremlins resurfaced, but not to the same degree encountered on Apollo 14. |
Lou Chinal
Member Posts: 1332
From: Staten Island, NY
Registered: Jun 2007
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posted 02-09-2009 05:26 PM
I found it: Page 512 of Baker's book "The History of Manned Spaceflight": On the Apollo end was a conventional drogue to which a probe, pirated from Apollo 14, would be used to draw the CSM on to the Docking Module. So the probe was flown again on ASTP, July 15-24, 1975. |
Mike Dixon
Member Posts: 1428
From: Kew, Victoria, Australia
Registered: May 2003
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posted 02-09-2009 06:04 PM
Good work Lou.Did a quick search online and found the reference to the ASTP docking issues and the A14 probe mentioned here. |
RichieB16
Member Posts: 582
From: Oregon
Registered: Feb 2003
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posted 02-12-2009 09:55 PM
Didn't A14 have problems with the probe when they were initially trying to dock with the LEM prior to LEM extraction. If I remember this right, they had problems there. If that's the case, the probe may have been returned to Earth to inspect it for any flaws or defects it may have had in case something in the design needed to be altered before A15. When it was found to be fine, I assume it would be reused to save parts. But, this is just a guess. |
Klaatu
Member Posts: 60
From: England
Registered: Sep 2007
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posted 08-04-2009 11:51 AM
At what point during TLI is the folded LM landing gear "deployed"? And was it ever filmed deploying? Maybe from the LM window? I often wondered if it literally "popped out" or opens quite slowly? Maybe there's film of it working during a test at Grumman?Editor's note: Threads merged. |
mikej
Member Posts: 481
From: Germantown, WI USA
Registered: Jan 2004
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posted 08-04-2009 12:07 PM
quote:
Originally posted by Klaatu:
I often wondered if it literally "popped out" or opens quite slowly? Maybe there's film of it working during a test at Grumman
One of the Spacecraft Films sets (based on the description, it looks like Apollo 13) contains footage of leg deployment tests. Yes, they really swing out! (At least in Earth gravity.) |
Proponent
Member Posts: 59
From: London
Registered: Oct 2008
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posted 08-04-2009 10:14 PM
Why would you wait until just before undocking to deploy the LM's legs? I'd have thought that you'd want to deploy them early. That way, if something went wrong, you'd have more time to work on the problem. The only reason I can think of for not deploying early is to reduce the exposure of the legs and landing pads to the CSM's RCS plumes. But this seems unlikely to be a factor since the rest of the LM could obviously withstand these plumes, so why would it be an issue for the legs? |
Lou Chinal
Member Posts: 1332
From: Staten Island, NY
Registered: Jun 2007
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posted 08-05-2009 12:04 AM
The legs are stowed until after LM/CSM were in orbit around the moon. Shortly before LM/CSM separation and lunar orbit insertion burn #1. |
stsmithva
Member Posts: 1940
From: Fairfax, VA, USA
Registered: Feb 2007
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posted 10-28-2009 10:31 PM
This thread is hopefully the appropriate place for me to finally post something I noticed last June in an issue of "Time for Kids", an 8-page magazine which my students receive each week. In that issue there was an article about the upcoming 40th anniversary of Apollo 11. Can you catch the mistake below?  Ah, I think a close-up of the caption will help:  "Approaches" the moon? Like that?!? According to this photo, the answer to the question that started this thread is "LM legs? Huh... those would have been useful." Or maybe I should have posted this in "You might be a space geek if..." |
Rick Mulheirn
Member Posts: 4208
From: England
Registered: Feb 2001
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posted 10-29-2009 01:51 PM
quote:
Originally posted by RichieB16:
Didn't A14 have problems with the probe when they were initially trying to dock with the LEM prior to LEM extraction.
Apollo 14 did have problems docking with the LM following TLI. Ed Mitchell put it down to water that somehow found its way in to the probe following a heavy rainstorm that delayed launch by 40 minutes and subsequently froze....though personally I doubt that. I have never thought the Apollo CM tucked up under the boost protective cover would have been that vulverable to rain. After docking with the LM inspection of the probe revealed nothing and Dr Mitchell concluded that any moisture evaporated while stowed in the CM or sublimated off following the decent of the LM to the surface. There were no further problems reported with the probe after that. |
LM-12
Member Posts: 3324
From: Ontario, Canada
Registered: Oct 2010
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posted 12-01-2012 08:33 PM
The Apollo 13 mission transcripts indicate that the LM landing gear was extended at 061:00:10 GET, which was about a half-hour before the 34-sec duration LM DPS burn at 061:29:43 GET that put the spacecraft back on a free-return trajectory.060:58:58 CC
Okay. The only item on page 10 is to deploy the landing gear.060:59:06 CDR
Okay, we'll do that now. 061:00:10 LMP
Okay. The landing gear are down and locked, Jack, and looking ahead now at page 11, we've done all of that.
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LM-12
Member Posts: 3324
From: Ontario, Canada
Registered: Oct 2010
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posted 12-02-2012 01:49 PM
quote:
Originally posted by spaceuk:
The legs were released fairly early on in the LM Activation Check List just prior to the LM undocking from the CSM
These LM landing gear deployment times taken from the mission transcripts seem to confirm that.- Apollo 11 - gear deploy (098:14:35) and undocking (100:12:00)
- Apollo 12 - gear deploy (104:48:56) and undocking (107:54:02)
- Apollo 14 - gear deploy (102:19:09) and undocking (103:47:42)
- Apollo 15 - gear deploy (098:34:51) and undocking (100:39:16)
- Apollo 16 - gear deploy (094:00:28) and undocking (096:13:31)
- Apollo 17 - gear deploy (106:22:11) and undocking (107:47:56)
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MadSci
Member Posts: 230
From: Maryland, USA
Registered: Oct 2008
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posted 12-04-2012 02:39 AM
quote:
Originally posted by stsmithva:
In that issue there was an article about the upcoming 40th anniversary of Apollo 11. Can you catch the mistake below?
Pretty hard to land without the Decent Stage - at least successfully.  |
Jay Chladek
Member Posts: 2272
From: Bellevue, NE, USA
Registered: Aug 2007
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posted 12-04-2012 03:37 AM
Yes, hard to land without a descent stage. But, considering the LM ascent stages were jettisoned and eventually crashed on the moon after the astronauts were back onboard (due to the mascons affecting the orbit), one could say they technically "approached" the moon later. Or, the orbit could have been at perigee when the photo was taken (lowest point of the orbit as opposed to its highest point).  Yes, an obvious hair split I know. Fascinating topic to be certain though. |
LM-12
Member Posts: 3324
From: Ontario, Canada
Registered: Oct 2010
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posted 10-05-2014 09:39 PM
The landing gear deploy switch was located on panel 8. Were all four landing gear legs deployed at the same time, or was the landing gear deployed in two stages?In some mission transcripts, the LANDING GEAR DEPLOY, FIRE command is given twice. On Apollo 15, at 04 02 34 32 and at 04 02 34 50 GET, for example. |
SpaceAholic
Member Posts: 4494
From: Sierra Vista, Arizona
Registered: Nov 1999
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posted 10-05-2014 10:35 PM
Here's where on Panel 8 (apologies for the reflection, too lazy to dismount the artifact from the case). To the right and in the last image is an example of the landing gear uplock and cutter assembly (one associated with each leg). The switch detonated a charge in the cutter separating the uplock strap where it converges in the center, releasing the spring loaded landing gear to extension. 
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LM-12
Member Posts: 3324
From: Ontario, Canada
Registered: Oct 2010
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posted 10-06-2014 08:15 AM
The Lunar Module News Reference indicates that there are two detonator cartridges in each uplock assembly: Each of the four landing gear assemblies is restrained in the stowed position by an uplock assembly that contains two detonator cartridges. While the LM is docked with the CM in lunar orbit, the LM Commander fires both detonator cartridges in each uplock assembly to deploy the landing gear. When all four landing gear assemblies have been deployed, a landing gear deployment indicator flag (talkback) on the control panel turns gray. |
SpaceAholic
Member Posts: 4494
From: Sierra Vista, Arizona
Registered: Nov 1999
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posted 10-06-2014 11:33 AM
One cutter assembly, two charges (each of the yellow capped ports on the example above hosted a cartridge). The talk-bag flag can also be seen on the panel (click on the image to view). |
LM-12
Member Posts: 3324
From: Ontario, Canada
Registered: Oct 2010
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posted 10-06-2014 02:58 PM
I think you can see a severed uplock strap in this Apollo 17 photo, just above where the primary strut and the secondary struts meet. |
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