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Author
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Topic: Apollo 13: Criticality, timing of engine burns
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TLIGuy
Member Posts: 207
From: Virginia
Registered: Jul 2013
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posted 05-15-2014 06:52 PM
   
I'm working on a project related to the use of the Omega Speedmaster to time Apollo 13's two critical burns (35 seconds and 5 minutes) as described in the NASA summary of mission events. I need to answer one question and confirm the correct events and the time.Of the two burns which one is considered most critical? I also need to make sure I'm identifying the correct events from the NASA chronology of events. I see a number of references to burns and want to make sure I'm identifying the two burn events and times correctly. Is this the correct event for the 35 second burn? Midcourse correction ignition to free-return trajectory (LM DPS) at 8:42:43 Is this the correct event for the 5 minute burn? Transearth injection ignition (LM DPS) at 02:40:39 Again, as always the expertise and help from this forum is greatly appreciated. |
Fra Mauro
Member Posts: 1624
From: Bethpage, N.Y.
Registered: Jul 2002
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posted 05-16-2014 07:49 AM
The free-return trajectory burn is the most critical since it prevent you from missing the Earth. |
uk spacefan
Member Posts: 168
From: London
Registered: Jan 2007
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posted 05-16-2014 10:45 AM
The mid-course correction burn took place approximately five hours after the explosion.As they approached the moon, the transearth injection burn (for 5 minutes) was to speed up their return home. The 35 second and 5 minute burn details are correct as per the timeline. Although these burns were equally important, the TEI burn would have probably been more critical. Full details are given from NASA here. Alternatively the mission report can be found here. |
moorouge
Member Posts: 2458
From: U.K.
Registered: Jul 2009
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posted 05-17-2014 01:04 AM
quote:
Originally posted by Fra Mauro:
The free-return trajectory burn is the most critical since it prevent you from missing the Earth.
Surely all the burns were equally critical, the failure of any one of them would have prevented a successful recovery. Don't forget the very last one that ensured they were in the re-entry corridor. Or is it a case of - to misquote George Orwell - all burns are equal but some are more equal than others. |
TLIGuy
Member Posts: 207
From: Virginia
Registered: Jul 2013
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posted 05-17-2014 05:42 AM
Thank you all for the help here. I agree that all of the burns would be equally important since the failure of any one of them would have resulted in the inability to return safely. For my project, I have very limited space to work and can only reference one event so I think I will go with the the 35 second burn since it seems to be the one most outside of this fine community are familiar with. |
MadSci
Member Posts: 230
From: Maryland, USA
Registered: Oct 2008
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posted 06-25-2014 11:58 PM
I'm not sure what your project is, however if you're interested, the original plan was to time the burns with the Command Module Interval Timer, a custom manufactured device resembling a kitchen timer. When Jack Swigert attempted to use it the timer, the knob fell off! This failure resulted in the need to use his watch instead.I am the current caretaker of the Interval Timer Knob in question. If you're interested in a photo please e-mail me and I'll be happy to provide one. |
Philip
Member Posts: 6002
From: Brussels, Belgium
Registered: Jan 2001
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posted 11-15-2018 11:24 AM
Jack Swigert's Speedmaster timed LM DPS burn was a 14 seconds burn performed April 16, 1970 at 04:31:28 to :42. |
Philip
Member Posts: 6002
From: Brussels, Belgium
Registered: Jan 2001
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posted 07-01-2019 01:07 PM
Today some info was released that during a SpeedyTuesday event in Singapore, Omega team-members confirmed that Lovell's Omega Speedmaster was used to time this burn on April 16, 1970. |
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