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Post by ka9q on Nov 13, 2011 5:07:54 GMT -4
This is curious, if you look at the exhaust shield under the down ward pointing thruster, GRUMMAN lined it with a thin plastic film. If you are referring to the four plume deflectors mounted on the descent stage that project up under the downward-pointing RCS engines on the ascent stage, they were constructed from metal. And no, they were not coated with plastic. Or at least they weren't coated with a plastic intended to withstand the heat of the plumes during flight. But it's entirely possible they were covered before launch with a plastic to protect them during manufacturing and installation. These plume deflectors were specifically designed to keep the downward RCS plumes from impinging on the thermal blankets protecting the descent stage. That's because the RCS thruster quads were mounted well above the top of the descent stage. But there was nothing below the descent engine to protect against its plume; the engine itself was the lowest point on the LM except for the landing probes. That is not to say that the descent engine didn't cause any heating problems. In fact, it did. But the exhaust plume wasn't the problem, rather it was the engine nozzle. It became extremely hot, probably to the point of visibly glowing. It therefore emitted a great deal of infrared that heated other structures on the bottom of the LM, in particular the landing radar antennas. That's why you'll find, on the bottom of every LM, a white rectangular shield mounted between the descent engine nozzle and the radar antenna to block direct IR radiation from the engine nozzle from striking the radar antenna.
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Post by Jason Thompson on Nov 13, 2011 5:09:43 GMT -4
gee let me think this thru The astronauts couldn't figure out how to view the stars while in cislunar space? gee buzz can we try turning the lights off for a moment... It's not a question of figuring it out, it's a question of having a reason to do it, or having a wish to do it, or having the time to do it. It takes several minutes to dark adapt. Some astroanuts did, some decided to focus on the job at hand rather than go sightseeing.
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Post by Jason Thompson on Nov 13, 2011 5:21:17 GMT -4
Why should we do your legwork for you? You claimed they didn't, and you used the series Moon Machines as your reference. Are you conceding that they did not in fact actually say they burned different propellants?
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Post by Jason Thompson on Nov 13, 2011 5:26:12 GMT -4
No, it says the engines were not the same, which is true. It does not say they burned different propellants.
Tell you what. I have that series on DVD. Tell me exactly when in the episode they said it and I'll look it up.
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Post by PhantomWolf on Nov 13, 2011 5:34:36 GMT -4
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Post by PhantomWolf on Nov 13, 2011 5:40:48 GMT -4
Yes, the show specifically says they were not the same. The engines weren't the same design. They just used the same fuels. Have a look at the four engines at the bottom of this page. They are the RCS, the SPS, the LM's Dsecent Engine and the Ascent Engine. They are clearly four different designs, but they all used the same fuel and oxidiser, Aerozine 50 as fuel and nitrogen tetroxide as the oxidiser.
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Post by PhantomWolf on Nov 13, 2011 5:46:52 GMT -4
so you are saying they both burned the same fuel So the final Assembly on the descent engine couldn't be tested either? that must have been reassuring to the astronauts. The descent engine was a non-critical component in the survival of the Astronuats. If it failed, they would just use the RCS to re-dock and come home. The SPS and the Ascent Engine were extremely critical, but they were also simple. Just because they weren't test fired doesn't mean they are likely to fail. My car hasn't been crash tested to test its safety systems, but I am pretty sure that in the event of me having an accident it will perform as designed.
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Post by gwiz on Nov 13, 2011 6:05:33 GMT -4
Just to make the point that engines virtually identical to the LM Ascent Stage engine were used in the upper stage of the Delta launch vehicle, and they were not test-fired before use either. www.astronautix.com/lvs/dela3000.htm
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Post by PhantomWolf on Nov 13, 2011 6:15:26 GMT -4
sorry the NASA reference you gave does not say they were the same fuel anyone can post on wikipedia Try re-reading the part I quoted, especially the bolded parts.
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Post by PhantomWolf on Nov 13, 2011 6:17:22 GMT -4
Neil Armstron specifically said he could not see stars from cislunar space. Try looking at the night sky from indoors with the lights on and see how many stars you can see, and before you say they shopuld have turned off the lights, explain why there was a need to look at the stars.
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Post by PhantomWolf on Nov 13, 2011 6:28:00 GMT -4
where does it say the oxidizer was nitrogen tetroxide for the ascent satag? You have now fully gone into trolling territory. You were the one that brought up the whole Ascent Engine having the Aerozine 50 fuel and nitrogen tetroxide oxidizer combination because it was on Moon Machines, and now that it's been shown to you that the Descent Engine was also Aerozine 50/Nitrogen Tetroxide the best you can do is complain that it doesn't name the Ascent oxidizer, which you already know since you brought it up first.
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Post by PhantomWolf on Nov 13, 2011 6:28:34 GMT -4
Armstrong never said he didn't look he said he couldn't see them Did he say he did look for them?
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Post by PhantomWolf on Nov 13, 2011 6:35:40 GMT -4
please show me the reference that states the ascent engine used nitrogen tetroxide oxidizer? You don't know how to use Google? I really don't know why I should bother, you don't seem to be interested in actually learning anything or doing anything to help yourself find the answers. I have students who do more work than you do, and they expect to be spoonfeed all the answers too. ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19730010173_1973010173.pdfHappy reading.
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Post by PhantomWolf on Nov 13, 2011 6:40:20 GMT -4
Armstrong said the stars can't be seen from cislunar space, period Actually, if you re-read the question you posted, he was asked about the Lunar Sky and what he said was that the sky on the moon appeared to be black with only the bright objects (the sun moon and some planets) being able to be seen. Since he never had the time to go into the LM's shadow and allow his eyes to adjust from being in the daylight of the lunar surface, he couldn't have seen the stars so what he said was true.
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Post by Jason Thompson on Nov 13, 2011 6:42:53 GMT -4
Page 7 of that document, quite a clear reference I'd say.
Playdor, I note that you are still unable or unwilling to provide your evidence that anyone actually said the APS and DPS used different fuels. Why must we dig out the precise statements while you are happy to hide behind your inferences and misunderstandings?
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