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Post by Obviousman on Nov 19, 2005 22:18:38 GMT -4
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Post by LunarOrbit on Nov 19, 2005 22:30:40 GMT -4
I'll await a better answer. That one didn't cut it Dave. They would not add a 14 hour LIOH canister, which was disposable after each use, when the oxygen tanks only provided a 8 hour maximum supply. It's not believable. Ok, Moon Man. Enough with the "it's not believable" garbage. It might not be believable to YOU but you are certainly not an expert so your beliefs in this matter do not carry a whole lot of weight. Saying you find something unbelievable does not mean it isn't possible, you have to PROVE IT. You and Margamatix wonder why we threaten to ban people like you. It is not your beliefs that upset us, it is your stubborn devotion to "beliefs" that you are unable to defend with facts that we find annoying. It is extremely frustrating when someone puts a lot of effort into a response to one of your claims only to get "sorry, that answer just doesn't cut it, it's unbelievable." in response. From now on I want you to put the same kind of effort into your responses that we do or I will ban you. I will not accept any more "it's just not believable" answers. And like I said in another thread tonight, I want you to stick to the rules of the debate: only one argument at a time, if you want to discuss other topics add them to your list.
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Post by Moon Man on Nov 19, 2005 22:32:57 GMT -4
Are you saying that I'm not allowed to post in or address other threads..?
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Post by Obviousman on Nov 19, 2005 22:35:05 GMT -4
[The Lunar Module also carries LiOH canisters, two installed for launch and replacements kept within the MESA (Modular Experiment Stowage Assembly), a section of the LM Descent Stage which is accessed during the lunar EVAs (Extra Vehicular Activity). The Apollo 13 emergency highlighted the incompatibility between the square canisters used in the CM, and the round ones used in the LM. It also demonstrated that having the LM's spare canisters outside the cabin was unfortunate. As was well illustrated in the movie, Apollo 13, the crew of this extraordinary mission had to build a rig out of available items in the cabin to allow the CM canisters to work in the LM's air circuit.]
[It is interesting to note that although the two canisters in the Command Module are identical, the two in the LM are incompatible with each other. Of the two, only the cartridge in the "primary" circuit is used, with the "secondary" only for emergencies. The secondary LiOH cartridge is actually interchangeable with the PLSS LiOH canister, allowing 12-14 hours of purification capacity while the PLSS's are onboard.]
[Scott, from 1998 correspondence - "Maybe this implication becomes the same as in the movie Apollo 13 - whereby it appears to be some form of mistake or oversight. Not so! As with all of Apollo (and to continuously emphasize this point), everything was very carefully planned and very precise in its objective. In this case, as you point out, the secondary cartridge will fit in the PLSS; and the LM was designed for only one primary cartridge - two people, smaller cabin, shorter life, etc., etc. Pretty clever to have the LM secondary and PLSS cartridges interchangeable!"]From the Apollo 15 Flight Journal history.nasa.gov/ap15fj/04troubleshoot_ptc.htm
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Post by LunarOrbit on Nov 19, 2005 22:38:58 GMT -4
Are you saying that I'm not allowed to post in or address other threads..? You can respond to threads that other people start but only to discuss the topic they brought up. Do not take other threads off topic.
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Post by Obviousman on Nov 19, 2005 22:45:00 GMT -4
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Post by scooter on Nov 19, 2005 22:46:58 GMT -4
Obviousman, Thanks for the ALSJ link,my DSL chewed on it for a while but worth the wait! It does seem to confirm the numbers. Now, a bit of a question. In my favorite link, the -7 PLSS consumption/duration curve has two LIOH lines, one for "LiOH (min performance, nominal wt 3.22 lbs, no thermal soak)" and one for "LiOH(min performance, min wt 3.12 lbs, with thermal soak)"
I'm not sure what the "thermal soak" and "min wt" variables affect. The two lines converge significantly on the "BTU/hr - EVA duration curve, so the difference diminishes over time in the EVA.
Again, terrific link, gobs of neat stuff there...
Dave
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Post by Obviousman on Nov 19, 2005 22:48:15 GMT -4
120:50:41 Gibson: Al, how you coming on weighing the water? [They are weighing the residual feedwater to give the PLSS engineers some data on use rates as a function of the available telemetry data on average heart rates, feedwater pressure and oxygen use.]
Ah! From same link as last.
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Post by Moon Man on Nov 19, 2005 22:55:36 GMT -4
[It is interesting to note that although the two canisters in the Command Module are identical, the two in the LM are incompatible with each other. Of the two, only the cartridge in the "primary" circuit is used, with the "secondary" only for emergencies. The secondary LiOH cartridge is actually interchangeable with the PLSS LiOH canister, allowing 12-14 hours of purification capacity while the PLSS's are onboard.] Which confirms what I said, They are larger then needed, and also add needless weight per canister.
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Post by scooter on Nov 19, 2005 23:04:40 GMT -4
exactly how much weight per canister was "wasted"? If the canisters were "identical", what's the weight difference? I still don't understand the 14 hr thing, but did see it in the ALSJ link. re the LM secondary cartridge. The PLSS docs clearly show a shorter time for the "same" cartridge. But again, where is the weight difference? Dave
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lonewulf
Earth
Humanistic Cyborg
Posts: 244
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Post by lonewulf on Nov 19, 2005 23:11:13 GMT -4
Preparing for emergencies makes "needless" weight? Remind me to never let you pack my suitcase, Moon Man.
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Post by Obviousman on Nov 19, 2005 23:37:14 GMT -4
[It is interesting to note that although the two canisters in the Command Module are identical, the two in the LM are incompatible with each other. Of the two, only the cartridge in the "primary" circuit is used, with the "secondary" only for emergencies. The secondary LiOH cartridge is actually interchangeable with the PLSS LiOH canister, allowing 12-14 hours of purification capacity while the PLSS's are onboard.] Which confirms what I said, They are larger then needed, and also add needless weight per canister. You need to read ALL of what was said: [Scott, from 1998 correspondence - "Maybe this implication becomes the same as in the movie Apollo 13 - whereby it appears to be some form of mistake or oversight. Not so! As with all of Apollo (and to continuously emphasize this point), everything was very carefully planned and very precise in its objective. In this case, as you point out, the secondary cartridge will fit in the PLSS; and the LM was designed for only one primary cartridge - two people, smaller cabin, shorter life, etc., etc. Pretty clever to have the LM secondary and PLSS cartridges interchangeable!"]I read this as meaning that if the primary LiOH system aboard the LM failed, they could use the secondary system and still have sufficient canisters for all the planned EVAs. If there were any problems with some of the PLSS canisters, they had spares, so the full EVAs could be continued. If they had a failure in the LM primary LiOH system AND problems with some of the PLSS cannisters, they still had LM life support and a limited EVA capability. Redundency. Engineers are like that - they think ahead.
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Post by scooter on Nov 19, 2005 23:43:35 GMT -4
and, again, being interchangable and identical, they still have the same weight and LiOH load/weight.
I don't see proof of a hoax here, nor even "evidence".
Dave
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Post by Obviousman on Nov 19, 2005 23:53:00 GMT -4
Beyond the Return valve, oxygen in the suit circuit flowed through one or the other of two carbon-dioxide/odor-removal canisters, the choice of canister depending on the settings of selectors mounted on the in-board face of the ECS cabinet. The canisters each contained beds of lithium hydroxide (LiOH) for carbon dioxide removal and beds of activated charcoal for odor control. The larger Primary canister had a capacity of 41 person-hours while the smaller, Secondary canister, identical to the canisters used in the backpacks, had a 14-hour capacity. Replacement LiOH cartridges - along with backpack replacements - were stored outside the cabin in the Modular Equipment Storage Assembly (MESA). On Apollo 17, replacement of the Primary ECS cartridge was done after wake-up on Day 2 of the lunar surface stay and then, a second time, about 35 hours later at the end of EVA-3. We note that the astronauts were outside the spacecraft during two 8-hour EVA periods during the time between the first changeout and the second. Consequently, the cartridge was used for about 38 person-hours, a figure close to the design lifetime. As a back up, there was a carbon dioxide sensor in the Suit Circuit which, if the CO2 partial pressure exceeded 7.6 mm of mercury, would have turned on warning lights. And, finally, because of the heavy - if relatively brief - dust load anticipated following the EVAs, the Primary canister was protected with a dust filter which, if it became clogged, could be bypassed by changing a valve setting.
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Post by Moon Man on Nov 20, 2005 0:02:20 GMT -4
I was just coming to post that info. If a 3.12 pound canister provides 14 hours then a little over half of the 3.12 pounds is all that is needed to provide a 8 hour supply. They only had oxygen available for 8 hours. They did 3 EVA's each. There were 6 canisters on board, thus they carried 8 needless pounds or so from the ground. NASA was concerned with weight but ignored this extra weight. Not one issue will prove a hoax, I was simply pointed this out since we are discussing the space suit. www.hq.nasa.gov/office/pao/History/alsj/apollo.engin.html
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