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  Mercury - Gemini - Apollo
  Lunar Landings

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Author Topic:   Lunar Landings
WAWalsh
Member

Posts: 806
From: Cortlandt Manor, NY
Registered: May 2000

posted 01-05-2004 01:58 PM     Click Here to See the Profile for WAWalsh   Click Here to Email WAWalsh     Edit/Delete Message   Reply w/Quote
A representation was made on a non-space board I visit that strikes me as simply wrong. According to an individual who states he was involved in the Apollo program and still down in Houston, Armstrong was the only one of the six commanders who actually made a "manual" landing on the Moon. The other five, apparently, were all computer controlled with Conrad, Shepard, Scott, Young and Cernan merely along for the ride and to take over if a problem occured. Has anyone else ever heard a representation that each of the landings was fully automated?

spaceuk
Member

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

posted 01-05-2004 02:47 PM     Click Here to See the Profile for spaceuk     Edit/Delete Message   Reply w/Quote
All the manned landings were targeted for computer controlled landings but the crew had the ability to take-over in the last few hundred feet to be able to choose a 'smooth' landing spot and avoid - as in Apollo-11 - hazardous aim points that the computer would have taken them.

Basically, the programs that ran were:

P63 - Landing maneouver braking program
P64 - Landing maneouver approach phase
P65 - Landing phase - auto
P66 - Rate of descent landing
P67 - Manual landing phase
P68 - Landing confirmation.

It was the P67 that was punched in on DSKY to override the auto approach/landing.

See my article on NASA site.

Phill
Author - Apollo On Board Computers

WAWalsh
Member

Posts: 806
From: Cortlandt Manor, NY
Registered: May 2000

posted 01-05-2004 03:11 PM     Click Here to See the Profile for WAWalsh   Click Here to Email WAWalsh     Edit/Delete Message   Reply w/Quote
Phill, interesting article. Did any of the missions actually rely on the autopilot through the entire descent, perhaps merely tapping in numbers in order to shift the targeted landing spot?

No doubt the computer played a role, but was it man flying the machine or machine flying the man?

WAWalsh
Member

Posts: 806
From: Cortlandt Manor, NY
Registered: May 2000

posted 01-05-2004 03:18 PM     Click Here to See the Profile for WAWalsh   Click Here to Email WAWalsh     Edit/Delete Message   Reply w/Quote
Never mind, decided to procrasinate a bit more and went over to the Lunar Surface Journal. Note at 113:00:51 for Apollo 17 has Cernan in P66 and flying with almost no computer support.

spaceuk
Member

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

posted 01-05-2004 03:25 PM     Click Here to See the Profile for spaceuk     Edit/Delete Message   Reply w/Quote
The target for each Apollo mission was decided many, many weeks in advance of the flight.

This was so that the programs could be 'wired-in' to the AGCs with the right coordinates and guidance equations.

There was little flexibility to 'target' another landing site outside of the prime area chosen for each mission. The landings could have been achieved 'fully - automatic' but man was needed in the loop to achieve a 'smooth touchdown'. Apollo-11 "fully automatic" may have been a disaster for the reason said in earlier posting. Also, Apollo-14 problems just before descent may have been difficult to have resolved without man-in-loop.

I'll put together a more detailed piece for you over next day or so.

Maybe email it to you direct since this is more technical than collecting - unless others interested as well?

Phill

FFrench
Member

Posts: 3131
From: San Diego
Registered: Feb 2002

posted 01-05-2004 03:55 PM     Click Here to See the Profile for FFrench     Edit/Delete Message   Reply w/Quote
I'm very interested!!

Larry McGlynn
Member

Posts: 966
From: Boston, MA
Registered: Jul 2003

posted 07-08-2006 09:25 PM     Click Here to See the Profile for Larry McGlynn   Click Here to Email Larry McGlynn     Edit/Delete Message   Reply w/Quote
The gentleman who claimed the other CDR’s flying after Apollo 11 allowed the AGC to fly the LM down to the lunar surface is incorrect. Although the LM could fly automatically to a landing and Floyd Bennett demonstrated it in the simulator. All LM CDR’s chose to land the LM in a semi-automatic mode using the P66 program (See Apollo Experience Report by Bennett).

All the CDR’s used semi-automatic control at touchdown. The CDR could flick a switch from PNGS AUTO to ATTITUDE-HOLD, forcing the computer into the P66 program or the Apollo Guidance Computer would automatically enter P66 just before LOW GATE at 500 feet.

The P66 program would allow the CDR to re-designate the landing site using the LPD (Landing Point Designator) to fly (with the help of the AGC)the LM to an appropriate landing site. P67, a fully manual program, was never engaged by any of the lunar landing CDR’s.

Each CDR engaged P66 at different altitudes. Those altitudes for each mission are listed below.

Apollo 11 - Armstrong switched to ATT HOLD / P66 at 550 feet
Apollo 12 - Conrad switched at 400 feet
Apollo 14 - Shepard switched at P66 at 370 feet
Apollo 15 - Scott switched at 400 feet
Apollo 16 - Young switched at 240 feet (he almost let the AGC land the LM)
Apollo 17 - Cernan switched at 240 feet

All of the CDR’s felt that they needed to take over due to the AGC steering the LM towards a bad landing site.

There is more to to the PDI, descent and touchdown including how the LPD was used to manuever the LM downrange to a new landing site, but it was would take about five pages to describe what occurred during a lunar landing. Understand that the LM had the ability to manuever up to 3 miles downrange from a 1000 foot altitude.

The other thing to take into consideration is that these astronauts were pilots and they were used to being in the loop at critical moments during a flight, so it is natural that they would choose to be active pilots at the moment of touchdown.

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

Sy Liebergot
Member

Posts: 499
From: Pearland, Texas USA
Registered: May 2003

posted 07-09-2006 09:11 AM     Click Here to See the Profile for Sy Liebergot   Click Here to Email Sy Liebergot     Edit/Delete Message   Reply w/Quote
Excellent, Larry! You are a true Apollo history docent and a buffet of Apollo knowlege.
Sy Liebergot
"Apollo EECOM: Journey of a Lifetime" www.apolloeecom.com

collocation
Member

Posts: 373
From: McLean, VA, USA
Registered: Feb 2004

posted 07-09-2006 01:18 PM     Click Here to See the Profile for collocation   Click Here to Email collocation     Edit/Delete Message   Reply w/Quote
Additional discussion regarding this subject can be found here: Lunar Landing Remote Control?

robsouth
Member

Posts: 769
From: West Midlands, UK
Registered: Jun 2005

posted 07-10-2006 05:38 PM     Click Here to See the Profile for robsouth     Edit/Delete Message   Reply w/Quote
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