Author Topic: Apollo Q&A  (Read 140650 times)

Offline the_other_Doug

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Re: Apollo Q&A
« Reply #300 on: 11/29/2015 08:59 PM »
With a crew of 3, someone can always be on duty with 3 8-hour shifts. Maybe that went into the thinking of early Apollo design, even before it was tasked with the moon mission? This would have been in the 1959-60 time frame, maybe they didn't trust the automation and telemetry of the time to allow all crew members to sleep at the same time. I believe it took several Gemini flights before both crew members were allowed to sleep at the same time. Also, there wasn't continuous communications with the spacecraft in low orbit missions until something like ASTP when it was able to relay through a higher communications satellite.

Exactly -- the Apollo crew complement was set at three well before it was tasked with the lunar landing mission.  That was when Apollo was to have been, at most, a translunar spacecraft, with the outside possibility of entering and leaving lunar orbit.

The three-man crew did come from the idea that the crew would rotate sleep cycles, so that one person at a minimum was always awake to monitor systems.  It also meant they could rig the schedules such that the entire crew was awake for important events, such as major maneuvers.

Not only did Gemini work with staggered sleep schedules up through Gemini VII/VI, when simultaneous sleep periods were approved, Apollo did the same thing for the first two flights.  So, on Apollos 7 and 8, the sleep periods were staggered and at least one person was always on duty.  As for alert and on duty,  well... sometimes not so much.  ;)
-Doug  (With my shield, not yet upon it)

Offline GClark

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Re: Apollo Q&A
« Reply #301 on: 11/30/2015 06:43 AM »
"Hey, Dick!  I fell asleep!"

"zzz...Huh, what?"

Offline nicp

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Re: Apollo Q&A
« Reply #302 on: 01/21/2016 06:42 PM »
Hi everyone, my first post after lurking for a decade or so, hoping this is a good place to ask.. please be gentle!
The later Apollo missions (according to multiple sources) upped the performance of the Saturn V somewhat (and did other stuff like use the SPS to lower lunar orbit , shaved excess metalwork etc) to increase the mass placed on the Moon.
But I'm curious what was done to the F-1 to increase thrust - if I recall correctly the 5 F-1s went from ~7.5Mlbf to about 7.7 or 7.8 between Apollos 4 and 15 and later.

Presumably (I don't know) those later engines existed quite some time before the later flights - and I'd be surprised if there were significant differences in turbo-pumps or whatever. I don't recall seeing any reference to even a small Isp improvement, so presumably this is mass-flow rate - so are you just letting the pumps work a little harder, shovelling propellant more quickly? And if so how do you do that?

Thanks
Nic
Where's my Guinness?

Offline the_other_Doug

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Re: Apollo Q&A
« Reply #303 on: 01/24/2016 06:00 AM »
Hi everyone, my first post after lurking for a decade or so, hoping this is a good place to ask.. please be gentle!
The later Apollo missions (according to multiple sources) upped the performance of the Saturn V somewhat (and did other stuff like use the SPS to lower lunar orbit , shaved excess metalwork etc) to increase the mass placed on the Moon.
But I'm curious what was done to the F-1 to increase thrust - if I recall correctly the 5 F-1s went from ~7.5Mlbf to about 7.7 or 7.8 between Apollos 4 and 15 and later.

Presumably (I don't know) those later engines existed quite some time before the later flights - and I'd be surprised if there were significant differences in turbo-pumps or whatever. I don't recall seeing any reference to even a small Isp improvement, so presumably this is mass-flow rate - so are you just letting the pumps work a little harder, shovelling propellant more quickly? And if so how do you do that?

Thanks
Nic

You actually have it right.  They increased the speed of the pumps a bit, and thereby the fuel and oxidizer flow increased, and the thrust increased a little (well, if you call 160 klb thrust per engine a little, but in comparison to the baseline...)

They also filled the tanks a little fuller, and shaved a few thousand pounds (!) of some as-it-turned-out-unneeded metal from the intertank structure and the engine cowlings.  The Marshall team built a lot of excess strength and capability into the S-IC, to give ample margins in case more performance was needed down the road.

Also, remember the rocket equation and especially the staged booster equation.  The first stage's weight has the least impact on the eventual payload, so shaving hundreds of pounds from first-stage weight has the same effect as shaving pounds of weight from your ultimate payload.  As long as the margin was there, von Braun's team used it.  When they needed a little more performance that margin was there to spare, and spare it they did.

The tune-up of the F-1's wasn't immediate, either.  IIRC, as early as AS-506 (AKA Apollo 11), the first stage combined thrust was rated up to 7.6 million pounds.  By the time Apollo 15 and the remaining J missions flew, the stage was at its highest performance level of 7.75 million pounds of thrust.  So, it took several iterations to bring the S-IC up to that level.

There was talk of F-1A engines, and even F-1B upgrades, but right around the time these ideas hit the design boards (though I think they actually test-fired some early F-1A configurations), production was stopped on the Saturn V, and well, there wasn't much point... *sigh*...
-Doug  (With my shield, not yet upon it)

Offline Proponent

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Re: Apollo Q&A
« Reply #304 on: 01/24/2016 12:42 PM »
The F-1A did indeed make it to the test stand (see the attachment), but it was not as far along as the J-2S.  I think it's virtually a certainty that had production continued, the J-2S would have been used in the upper stages: see the proposed SA-520 (the initial production run was comprised of vehicles SA-501 through -515).

Online wolfpack

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Re: Apollo Q&A
« Reply #305 on: 03/02/2016 10:45 PM »
Did the "milkstool" launches at 39B require sound suppression water in the flame trench? It looks like from several photos (ASTP) that there's no steam coming out the trench, which led me to wonder if the IB's engine exit plane height negated the need for water.
« Last Edit: 03/03/2016 02:09 PM by wolfpack »

Offline Jim

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Re: Apollo Q&A
« Reply #306 on: 03/03/2016 12:13 AM »
Did the "milkstool" launches at 38B require sound suppression water in the flame trench? It looks like from several photos (ASTP) that there's no steam coming out the trench, which led me to wonder if the IB's engine exit plane height negated the need for water.

Saturn V didn't use water for sound suppression.  It was only to protect the ML
« Last Edit: 03/03/2016 12:14 AM by Jim »

Offline dks13827

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Re: Apollo Q&A
« Reply #307 on: 03/05/2016 01:08 AM »
See if anyone has heard of this. Read somethings years ago that Apollo 11 did not depress before undocking the LM. The extra impulse helped cause the 'landing long' that put the LM into the boulder field.
No they depressurized the tunnel.  The LM backed away from the CSM and that extra few feet per second was part of the reason they were long.

Offline DaveJes1979

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Re: Apollo Q&A
« Reply #308 on: 08/07/2016 11:19 PM »
How big a hazard was the threat of falling down on a lunar EVA?  I am thinking especially of hitting a rock and cracking the glass on one's helmet.  There were many trips and falls through the Apollo program, but it seems that no damage was done in practice.

I assume a fair bit of engineering went into the issue.  What was the helmet glass expected to withstand if it struck something?

Offline Jim

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Re: Apollo Q&A
« Reply #309 on: 08/07/2016 11:38 PM »
Lexan was helmet material. 

Offline the_other_Doug

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Re: Apollo Q&A
« Reply #310 on: 08/08/2016 04:27 AM »
Not only was the bubble helmet Lexan (a hard clear plastic), there were usually at least one and often two or even three other visors covering some or all of the helmet's face.  There was another clear Lexan shield that pulled down that served as a micrometeoroid shield, followed by the gold-coated visor that provided UV and IR protection, as well as literal glare and bright sunlight protection.

Finally, smaller pull-over and pull-out opaque shades and shields could be pulled out from the sides and, starting on Apollo 14, down from the top (actually starting on Apollo 13, but didn't have the chance to be used on the lunar surface on that flight).  These were designed to block out direct glare from the Sun.  Interestingly, the one guy who got to walk on the Moon who narrowed his vision the most by having all the opaque shields pulled down to their maximum was Al Shepard.

In lunar gravity, as well, you fall more slowly.  This gives you more time to prepare for your impact with the ground, and the speed at which you you hit the ground is also lower than would be the case on Earth.  I recall several times when a guy would trip and start to fall forward, but be able to literally run his feet back up under himself and recover without even falling.  Even when they did fall, the Moonwalkers tended to anticipate their landings and were able to catch themselves with their hands and push themselves back up onto their feet well before their helmets could have hit the ground.  They got their camera lenses dusty when this happened, but didn't break them, or their helmets...
-Doug  (With my shield, not yet upon it)

Online Phillip Clark

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Re: Apollo Q&A
« Reply #311 on: 08/19/2016 07:44 AM »
Does anyone know which of the Apollo lunar missions had the greatest re-entry velocity, thus making its cre the fastest humans?

Or maybe the fastest humans were at trans-lunar injection? - although I doubt this.

Thanks!
« Last Edit: 08/19/2016 08:11 AM by Phillip Clark »
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Offline Proponent

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Re: Apollo Q&A
« Reply #312 on: 08/19/2016 08:49 AM »
The answer may depend on the reference frame you choose, but I'm pretty sure that Apollo by the Numbers will provide some answers.

Online Phillip Clark

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Re: Apollo Q&A
« Reply #313 on: 08/19/2016 11:33 AM »
According to Apollo by Numbers the greatest velocity - relative to the Earth's sirface - was the re-entry of Apollo 10, 12.004 km/s.
I've always been crazy but it's kept me from going insane - WJ.

Offline Mbhoward

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Re: Apollo Q&A
« Reply #314 on: 11/08/2016 09:50 PM »
Any idea what the g loading on the crew was during reentry? I imagine at that speed it was pretty hefty?

Offline Proponent

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Re: Apollo Q&A
« Reply #315 on: 11/09/2016 01:22 PM »
Is it really too difficult to check  Apollo by the Numbers?  You need not even google it, since the link is provided just two posts above yours.
« Last Edit: 11/12/2016 12:37 PM by Proponent »

Offline penguin44

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Re: Apollo Q&A
« Reply #316 on: 11/12/2016 07:01 AM »
Why was Apollo 17 higher g than 13?

Online Poole Amateur

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Re: Apollo Q&A
« Reply #317 on: 11/21/2016 01:54 PM »
Why was Apollo 17 higher g than 13?

On reentry? I believe Apollo 13 came in at a shallower than nominal entry angle, hence the longer time she was out of communications, and therefore gave the crew less of a squeeze...

If I'm wrong, would be glad to know just for learning's sake.

Offline Davp99

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Re: Apollo Q&A
« Reply #318 on: 11/24/2016 08:51 PM »
It would seem that Apollo 12, According to the NASA LEM Med kit, Those 2 guys seemed to be in the Most Pain,," Had trouble Sleeping..discomfit etc,,:

Lunar Module Medical Kit [2]
Rucksack
1
Stimulant Pill s (Dexedrine)
4
Pain Pills Darvon
4
Decongestant Pills (Actifed)
8
Diarrhea Pills (Lomotil)
12
Band-Aids
6
Compress Bandages
2
Eye Drops (Methylcellulose)
1
Antibiotic Ointment (Neosporin)
1
Sleeping Pills Seconal
6
Anesthetic Eye Drops
1
Nose Drops (Afrin)
1
Urine Collection and Transfer   
  Assembly Roll-On Cuffs
6
Pronestyl
12
Injectable Drug Kit
Injectable Drug Kit Rucksack
1
Lidocaine (cardiac)
8
Atropine (cardiac)
4
Demerol (pain)
2
   Please excuse my <Bolding,,been awhile since I used DOS typing>
« Last Edit: 11/24/2016 09:07 PM by Davp99 »
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Offline nicp

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Re: Apollo Q&A
« Reply #319 on: 12/24/2016 06:57 PM »
The Wikipedia article on Apollo 8 mentions that the SPS engine needed 'coating' (edit: with a short burn)
or it could explode in a long burn.
Is that right? I don't recall reading that anywhere else and variants of that engine (which may differ a lot, I've no idea) are used on various rockets and spacecraft.
« Last Edit: 12/24/2016 07:00 PM by nicp »
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