Apollo 13 LM upper stage.

On 3/3/2011 7:23 AM, Brian Thorn wrote:
On Thu, 03 Mar 2011 00:41:23 -0800, Pat
wrote:

And that assumes LM engine was run at full thrust.
Does anyone know if that was the case in Apollo 13?

Remember, Aquarius fired its DPS engine three times: Free Return (MET
61:29:43), PC+2 (MET 79:27:39) and Course Correction (MET 105:18:28).

According to Lovell's _Lost Moon_, the Free Return burn started at low
throttle and then went up to 40%.

The PC+2 burn was 5 seconds at minimum thrust, then 21 seconds at 40%
thrust, and finally 4 minutes at full thrust. Lovell handled the
throttle, the computer handled the timing.

The Course Correction burn was at low throttle (10%).

Thanks, I'd always wondered about the specifics of that operation.

Pat

On Mar 3, 1:24*pm, Pat Flannery wrote:
On 3/3/2011 7:23 AM, Brian Thorn wrote:





On Thu, 03 Mar 2011 00:41:23 -0800, Pat
wrote:

And that assumes LM engine was run at full thrust.
Does anyone know if that was the case in Apollo 13?

Remember, Aquarius fired its DPS engine three times: Free Return (MET
61:29:43), PC+2 (MET 79:27:39) and Course Correction (MET 105:18:28).

According to Lovell's _Lost Moon_, the Free Return burn started at low
throttle and then went up to 40%.

The PC+2 burn was 5 seconds at minimum thrust, then 21 seconds at 40%
thrust, and finally 4 minutes at full thrust. Lovell handled the
throttle, the computer handled the timing.

The Course Correction burn was at low throttle (10%).

Thanks, I'd always wondered about the specifics of that operation.

Pat- Hide quoted text -

- Show quoted text -

i still wonder at the actual release time if the LM upper stage had
seperated and fired all its engines to depletion if it could of been
put in heliospheric orbit...

i know it was close to earth by necessity and the time short, but the
difference in angles between mised earth, burned up and skipped off
atmosphere was just a few degrees if i remember the discussion at the
tme

at least snoopy is probably in heliospheric orbit

On Mar 2, 12:34 pm, Jeff Findley wrote:
In article a5dbee9b-47ce-483b-ae12-4e88cd16def1
@o30g2000pra.googlegroups.com, says...





On Mar 2, 8:54 am, Pat Flannery wrote:
On 3/1/2011 6:31 PM, Ken S. Tucker wrote:

On Mar 1, 3:31 am, Pat wrote:
On 2/28/2011 12:47 PM, Ken S. Tucker wrote:

It was challenging enough to have the LM thrust the CSM load,
something it was never designed for, or spec'd for, but Grumman
put enough balls into the upper-LM stage to do it!

It also had to sustain heavy loads on the docking collar then the CSM
braked itself and the LM into lunar orbit.
Pat

"heavy loads", Not really, 1 inch / sec is an easy closing speed.
(I can sim a soft landing on the moon doing that, so can automated
landings).

No, when the CSM with the LM attached to its nose entered lunar orbit,
it used the big service module engine to do it.
The service module engine produced 21,900 lbs. thrust.
This would be pushing on the heavy fully-fueled LM's docking collar.
When they fired up the LM descent engine on Apollo 13 its total thrust
when running full-out was only 10,125 lbs. and they may not have run it
at full thrust either.
Push on it from the CSM side or from the LM side and the total stress on
the docking collar assembly remains the same.
Pat

Not quite sure your thesis holds Pat, cuz the CSM is quite a bit
heavier
than the Descent Stage, so the force = mass x acceleration would need
to be all figured out.

True. A quick web search suggests that the fully loaded CSM mass was
nearly twice that of the fully loaded LM. So, the force on the LM side
of the docking interface would have been something around 7300 lbs
during the burn of the SM's engine. The actual value would go up as the
burn progressed due to the mass of fuel/oxidizer expended by the SM's
engine.

I'm not sure about the force caused by the LM's engine on the docking
interface during Apollo 13 because to figure that out, you'd need to
know the mass of the CSM and LM at the time of the burn. I'm sure
someone at NASA figured that out (close enough) to do the burn, but that
still would have been an estimate given the damage to the SM.
Jeff

As you know, NASA tested everything, but using a descent engine to
push LEM+CSM wasn't (AFAIK) ever tested, so they used an experimental
method to save 3 guys over the far side of the moon.
Figures on thrusts, forces and mass are likely close, so it *should*
work
and it did, (thanks to posters, Mr. Thorn).
Good to consider the exercise.
Ken

In article 12231cd8-f184-472b-adb7-541348b93e08
@a11g2000pro.googlegroups.com, says...

As you know, NASA tested everything, but using a descent engine to
push LEM+CSM wasn't (AFAIK) ever tested, so they used an experimental
method to save 3 guys over the far side of the moon.
Figures on thrusts, forces and mass are likely close, so it *should*
work
and it did, (thanks to posters, Mr. Thorn).
Good to consider the exercise.
Ken

There was some thought put into this sort of thing ahead of time. I
believe that this was one of the reasons that the LEM and CM computer
used the identical hardware. If one in the CM failed on the trip out,
you had the one in the LEM as a backup to get you home. :-)

Of course, not every engineering group shared this design philosophy,
otherwise the LiOH cannisters designed for the CM would have been
identical to those in the LEM. :-(

Jeff
--
" Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry
Spencer 1/28/2011

how much fuel had been used by the descent engine as the LM was
released?

were the tanks near empty?

On Mar 4, 3:48*pm, " wrote:
how much fuel had been used by the descent engine as the LM was
released?

were the tanks near empty?

I can't say, and knowing NASA/Apollo records that are mostly lost or
intentionally destroyed, it's unlikely we'll ever know.

http://translate.google.com/#
Brad Guth, Brad_Guth, Brad.Guth, BradGuth, BG / “Guth Usenet”

On 03/04/2011 01:47 PM, Jeff Findley wrote:
In article12231cd8-f184-472b-adb7-541348b93e08
@a11g2000pro.googlegroups.com, says...

As you know, NASA tested everything, but using a descent engine to
push LEM+CSM wasn't (AFAIK) ever tested, so they used an experimental
method to save 3 guys over the far side of the moon.
Figures on thrusts, forces and mass are likely close, so it *should*
work
and it did, (thanks to posters, Mr. Thorn).
Good to consider the exercise.
Ken

There was some thought put into this sort of thing ahead of time. I
believe that this was one of the reasons that the LEM and CM computer
used the identical hardware. If one in the CM failed on the trip out,
you had the one in the LEM as a backup to get you home. :-)

Not quite identical - the "software" was different, and since the
software was woven into the core ropes, the two computers were not
*quite* interchangeable - the core ropes would have had to be swapped.

On 03/04/2011 10:42 AM, Ken S. Tucker wrote:
On Mar 2, 12:34 pm, Jeff wrote:
In articlea5dbee9b-47ce-483b-ae12-4e88cd16def1
@o30g2000pra.googlegroups.com, says...





On Mar 2, 8:54 am, Pat wrote:
On 3/1/2011 6:31 PM, Ken S. Tucker wrote:

On Mar 1, 3:31 am, Pat wrote:
On 2/28/2011 12:47 PM, Ken S. Tucker wrote:

It was challenging enough to have the LM thrust the CSM load,
something it was never designed for, or spec'd for, but Grumman
put enough balls into the upper-LM stage to do it!

It also had to sustain heavy loads on the docking collar then the CSM
braked itself and the LM into lunar orbit.
Pat

"heavy loads", Not really, 1 inch / sec is an easy closing speed.
(I can sim a soft landing on the moon doing that, so can automated
landings).

No, when the CSM with the LM attached to its nose entered lunar orbit,
it used the big service module engine to do it.
The service module engine produced 21,900 lbs. thrust.
This would be pushing on the heavy fully-fueled LM's docking collar.
When they fired up the LM descent engine on Apollo 13 its total thrust
when running full-out was only 10,125 lbs. and they may not have run it
at full thrust either.
Push on it from the CSM side or from the LM side and the total stress on
the docking collar assembly remains the same.
Pat

Not quite sure your thesis holds Pat, cuz the CSM is quite a bit
heavier
than the Descent Stage, so the force = mass x acceleration would need
to be all figured out.

True. A quick web search suggests that the fully loaded CSM mass was
nearly twice that of the fully loaded LM. So, the force on the LM side
of the docking interface would have been something around 7300 lbs
during the burn of the SM's engine. The actual value would go up as the
burn progressed due to the mass of fuel/oxidizer expended by the SM's
engine.

I'm not sure about the force caused by the LM's engine on the docking
interface during Apollo 13 because to figure that out, you'd need to
know the mass of the CSM and LM at the time of the burn. I'm sure
someone at NASA figured that out (close enough) to do the burn, but that
still would have been an estimate given the damage to the SM.
Jeff

As you know, NASA tested everything, but using a descent engine to
push LEM+CSM wasn't (AFAIK) ever tested, so they used an experimental
method to save 3 guys over the far side of the moon.
Figures on thrusts, forces and mass are likely close, so it *should*
work
and it did, (thanks to posters, Mr. Thorn).
Good to consider the exercise.

A docked DPS burn may not have been *tested*, but it was definitely
*considered* - it was on the books as a contingency procedure for
Apollos 10-12.

On Mar 4, 5:32 pm, "Jorge R. Frank" wrote:
On 03/04/2011 10:42 AM, Ken S. Tucker wrote:



On Mar 2, 12:34 pm, Jeff wrote:
In articlea5dbee9b-47ce-483b-ae12-4e88cd16def1
@o30g2000pra.googlegroups.com, says...

On Mar 2, 8:54 am, Pat wrote:
On 3/1/2011 6:31 PM, Ken S. Tucker wrote:

On Mar 1, 3:31 am, Pat wrote:
On 2/28/2011 12:47 PM, Ken S. Tucker wrote:

It was challenging enough to have the LM thrust the CSM load,
something it was never designed for, or spec'd for, but Grumman
put enough balls into the upper-LM stage to do it!

It also had to sustain heavy loads on the docking collar then the CSM
braked itself and the LM into lunar orbit.
Pat

"heavy loads", Not really, 1 inch / sec is an easy closing speed.
(I can sim a soft landing on the moon doing that, so can automated
landings).

No, when the CSM with the LM attached to its nose entered lunar orbit,
it used the big service module engine to do it.
The service module engine produced 21,900 lbs. thrust.
This would be pushing on the heavy fully-fueled LM's docking collar.
When they fired up the LM descent engine on Apollo 13 its total thrust
when running full-out was only 10,125 lbs. and they may not have run it
at full thrust either.
Push on it from the CSM side or from the LM side and the total stress on
the docking collar assembly remains the same.
Pat

Not quite sure your thesis holds Pat, cuz the CSM is quite a bit
heavier
than the Descent Stage, so the force = mass x acceleration would need
to be all figured out.

True. A quick web search suggests that the fully loaded CSM mass was
nearly twice that of the fully loaded LM. So, the force on the LM side
of the docking interface would have been something around 7300 lbs
during the burn of the SM's engine. The actual value would go up as the
burn progressed due to the mass of fuel/oxidizer expended by the SM's
engine.

I'm not sure about the force caused by the LM's engine on the docking
interface during Apollo 13 because to figure that out, you'd need to
know the mass of the CSM and LM at the time of the burn. I'm sure
someone at NASA figured that out (close enough) to do the burn, but that
still would have been an estimate given the damage to the SM.
Jeff

As you know, NASA tested everything, but using a descent engine to
push LEM+CSM wasn't (AFAIK) ever tested, so they used an experimental
method to save 3 guys over the far side of the moon.
Figures on thrusts, forces and mass are likely close, so it *should*
work
and it did, (thanks to posters, Mr. Thorn).
Good to consider the exercise.

A docked DPS burn may not have been *tested*, but it was definitely
*considered* - it was on the books as a contingency procedure for
Apollos 10-12.

Thanks, that's interesting to know.
btw, we attended a talk given by Lovell on 13, he's a hellva good
speaker,
stood at a podium for about 2 hours. He brought up the subject of fins
on the
S5, and said something like 'Von Braun put fins on everything, we
never
figured out why', that cracked us up.
He emphasized the importance of celestrial navigation, on the re-
entry
return, IIRC it was the fastest manned re-entry ever, so bleeding that
energy had to be done 'near' perfectly.
Regards
Ken

On 3/5/2011 3:46 AM, Ken S. Tucker wrote:
He brought up the subject of fins
on the
S5, and said something like 'Von Braun put fins on everything, we
never
figured out why', that cracked us up.

From what I've heard, the little fins on the Saturn V first stage were
to make sure the first stage stayed straight in relation to the second
stage when they separated.

Pat