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Author
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Topic: Apollo lunar module maximum descent speed
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Mike Dixon
Member Posts: 1428
From: Kew, Victoria, Australia
Registered: May 2003
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posted 01-07-2015 08:03 PM
   
Tried to find this information online and no success. Does anyone know the maximum descent speed the Apollo lunar module reached prior to landing? I believe I've read somewhere it was of paramount concern that it drop quickly toward the surface to conserve fuel but not sure if that's correct or not. |
Lou Chinal
Member Posts: 1332
From: Staten Island, NY
Registered: Jun 2007
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posted 01-07-2015 08:49 PM
This is a very good question. I have heard Neil and Buzz say the DPS was burning right down to contact.Several of the LM people have said the LM could withstand a drop of 6-10 feet (I don't know if that earth's gravity or moon gravity). |
sev8n
Member Posts: 236
From: Dallas TX USA
Registered: Jul 2012
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posted 01-07-2015 09:50 PM
Isn't a 6 foot drop on earth roughly the equivalent of a 10 foot drop on the moon? |
Mike Dixon
Member Posts: 1428
From: Kew, Victoria, Australia
Registered: May 2003
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posted 01-07-2015 10:23 PM
I guess I'd also like to know from what height did LM descent commence and the time between that event and the landing so we can at least determine an average speed. |
Robert Pearlman
Editor Posts: 43576
From: Houston, TX
Registered: Nov 1999
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posted 01-07-2015 10:35 PM
According to a 1970 NASA technical memorandum (Apollo Lunar Descent and Ascent Trajectories), pre-mission planning for Apollo 11 called for powered descent initiation at 48,814 feet, 12 minutes before probe contact (touchdown). |
Mike Dixon
Member Posts: 1428
From: Kew, Victoria, Australia
Registered: May 2003
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posted 01-07-2015 10:48 PM
Thanks Rob.  So around 46 mph average. Now to the first question regarding highest speed and I'm guessing it wouldn't be all that different. |
Headshot
Member Posts: 891
From: Vancouver, WA, USA
Registered: Feb 2012
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posted 01-08-2015 08:43 AM
I recall reading somewhere that Armstrong had calculated the LM could survive a drop of 40 feet to the lunar surface without damage. Grumman engineers confirmed his figures, but added that such an occurrence would not be pleasant for the crew, even though they would be uninjured as well. |
Jim Behling
Member Posts: 1488
From: Cape Canaveral, FL
Registered: Mar 2010
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posted 01-08-2015 09:58 AM
quote:
Originally posted by Mike Dixon:
Now to the first question regarding highest speed and I'm guessing it wouldn't be all that different.
Not true, at the start of PDI, it is at orbital speed. Look at page 8 of the document that Robert posted. |
Glint
Member Posts: 1044
From: New Windsor, Maryland USA
Registered: Jan 2004
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posted 01-08-2015 03:51 PM
quote:
Originally posted by Mike Dixon:
So around 46 mph average.
If your interest only lies in the vertical speed, then yes. |
Mike Dixon
Member Posts: 1428
From: Kew, Victoria, Australia
Registered: May 2003
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posted 01-08-2015 04:17 PM
Thanks to all who contributed |
Lou Chinal
Member Posts: 1332
From: Staten Island, NY
Registered: Jun 2007
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posted 01-09-2015 10:16 PM
I can suggest referencing this old post. One of the engineers figured it out (I think his name was Bob Tisdale. |
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