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  LM Descent Engine Fluctuation

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Author Topic:   LM Descent Engine Fluctuation
collocation
Member

Posts: 387
From: McLean, VA
Registered: Feb 2004

posted 06-26-2006 08:29 AM     Click Here to See the Profile for collocation   Click Here to Email collocation     Edit/Delete Message   Reply w/Quote
If this has already been covered, I apologize. Came across a site www.doneyeyles.com/LM/Tales.html that described an Apollo 111 descent engine fluctuation in addtion to the well know program alarms, was this fluctuation well know to the historians

Larry McGlynn
Member

Posts: 1267
From: Boston, MA
Registered: Jul 2003

posted 06-26-2006 10:00 AM     Click Here to See the Profile for Larry McGlynn   Click Here to Email Larry McGlynn     Edit/Delete Message   Reply w/Quote
Collocation,

The Castleing effect is known to historians and will be further explained in a book about the Apollo Guidance Computer coming out next year.

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Larry McGlynn
A Tribute to Apollo

collocation
Member

Posts: 387
From: McLean, VA
Registered: Feb 2004

posted 06-26-2006 10:09 AM     Click Here to See the Profile for collocation   Click Here to Email collocation     Edit/Delete Message   Reply w/Quote
Thanks, how critical was this problem on a scale of 1-10, with 10 resulting in an abort

ilbasso
Member

Posts: 1522
From: Greensboro, NC USA
Registered: Feb 2006

posted 06-26-2006 10:26 AM     Click Here to See the Profile for ilbasso   Click Here to Email ilbasso     Edit/Delete Message   Reply w/Quote
Corrected link - http://www.doneyles.com/LM/Tales.html

Larry McGlynn
Member

Posts: 1267
From: Boston, MA
Registered: Jul 2003

posted 06-26-2006 10:57 AM     Click Here to See the Profile for Larry McGlynn   Click Here to Email Larry McGlynn     Edit/Delete Message   Reply w/Quote
I know Don from MIT lectures. He is a great guy and loves this particular problem with "Castlellations."

If you read the presentation, then you can see how the problem would have lead to an abort on Apollo 11. Don concluded more accurately in the software on the lag time between the throttle and the engine reaction.

If Don followed the engineering guidelines on the projected lag time, then the LM would have become unstable during the final approach and the crew would have had to abort.

How critical was this issue? Don would probably rate it as a 6. It was easily resolved by Apollo 14. Don tweaked the program to factor in the accurate lag time. Much like he tweaked the registers on the AGC software to omit the abort guidance switch

------------------
Larry McGlynn
A Tribute to Apollo

collocation
Member

Posts: 387
From: McLean, VA
Registered: Feb 2004

posted 06-26-2006 01:50 PM     Click Here to See the Profile for collocation   Click Here to Email collocation     Edit/Delete Message   Reply w/Quote
Thank you very much, do you happen to know the author or name of the book that is coming out regarding the computer system

spaceuk
Member

Posts: 2113
From: Staffs, UK
Registered: Aug 2002

posted 06-28-2006 05:02 PM     Click Here to See the Profile for spaceuk     Edit/Delete Message   Reply w/Quote
Excellent read - thoroughly enjoyed Don's recall.

I have swift-read the article but have captured it for a more detailed read later.

If you enjoyed this article you would enjoy Eldon Hall's book "Journey To The Moon".

A very "early" book c.1964 Lunar Missions and Explorations is a good intro book (if you can get hold of it) of how you would go about planning a lunar landing mission and undertaking it. There are many more technically orientated books from the mid to late 60's on topics like space engineering and inertial guidance - again if you can source them.

There are the NASA technical reports and the many documents associated with each mission from both NASA and its contractors (like Raytheon,MIT ) .


Phill
spaceuk


spaceuk
Member

Posts: 2113
From: Staffs, UK
Registered: Aug 2002

posted 06-28-2006 05:04 PM     Click Here to See the Profile for spaceuk     Edit/Delete Message   Reply w/Quote
another good source - if you have the will power to stay with some of the documents is at:-
http://klabs.org/history/history_docs/mit_docs/index.htm

Phill
spaceuk

Larry McGlynn
Member

Posts: 1267
From: Boston, MA
Registered: Jul 2003

posted 06-28-2006 09:55 PM     Click Here to See the Profile for Larry McGlynn   Click Here to Email Larry McGlynn     Edit/Delete Message   Reply w/Quote
You also want to read Floyd Bennett's Apollo Experience Report: Mission Planning for Lunar Descent and Ascent.

Floyd was in charge of the LM descent planning during the 60's.

------------------
Larry McGlynn
A Tribute to Apollo

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