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Post by brotherofthemoon on Jul 21, 2009 11:40:19 GMT -4
At what altitude in the scorching radiation hell of the lunar vacusphere does the alleged "concept" of pounds-per-square-inch begin?
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Ian Pearse
Mars
Apollo (and space) enthusiast
Posts: 308
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Post by Ian Pearse on Jul 21, 2009 11:54:51 GMT -4
Darn it I wish my memory were better. I was watching a documentary on a particular armoured vehicle the other day (may have been the Chaffee light tank, or perhaps the M113 APC), and it was pointed out that the ground pressure from this thing was less than a soldier in a boot. ([Weight of vehicle divided by area of tracks on ground] versus [weight of soldier divided by area of soles of boots]). Thus the thing was liked very much for its' ability to cross marshy areas. Would be a very nice illustration - if I could remember the details... (Eeep, may even have been the British APC used in the Falklands... will search tonight) I recently saw a programme on the Scimitar light tank that said exactly that.
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Post by randombloke on Jul 21, 2009 12:44:10 GMT -4
At what altitude in the scorching radiation hell of the lunar vacusphere does the alleged "concept" of pounds-per-square-inch begin? Uh, all of them, I think. Pretty sure concepts like mass and area are the sort of thing that doesn't change from planet to planet...
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Post by gillianren on Jul 21, 2009 13:59:35 GMT -4
Uh, all of them, I think. Pretty sure concepts like mass and area are the sort of thing that doesn't change from planet to planet... It's an in-joke, I'm afraid. We actually did have a guy once ask, "How far above the surface of the Moon does this alleged vacuum start?" I forget whose "searing radiation hell" is, though.
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Post by laurel on Jul 21, 2009 14:28:01 GMT -4
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Post by blackstar on Jul 21, 2009 14:35:16 GMT -4
Isn't the guy also quoting the weight of the LEM on Earth, not in 1/6th g? Hence the force applied by the LEM to the surface material is decidedly less than he is implying.
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Bob B.
Bob the Excel Guru?
Posts: 3,072
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Post by Bob B. on Jul 21, 2009 14:53:06 GMT -4
Isn't the guy also quoting the weight of the LEM on Earth, not in 1/6th g? Hence the force applied by the LEM to the surface material is decidedly less than he is implying. Yes, and he's also leaving out the weight of the astronauts' spacesuits.
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Post by blackstar on Jul 21, 2009 15:10:29 GMT -4
Isn't the guy also quoting the weight of the LEM on Earth, not in 1/6th g? Hence the force applied by the LEM to the surface material is decidedly less than he is implying. Yes, and he's also leaving out the weight of the astronauts' spacesuits. Also surely the LEM with its engine firing was practically at zero velocity vertically at the moment when it touched down? I mean there was actually a significant force acting against the pull of gravity. An astronaut bunny hopping/loping may have come down with greater pressure even under 1/6th g.
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Post by gillianren on Jul 21, 2009 17:40:36 GMT -4
Must . . . resist . . . temptation . . . to read entire thread! The crazy! It burns!
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Post by JayUtah on Jul 21, 2009 20:45:27 GMT -4
There is a marked qualitative difference between the fluid pressure of an exhaust plume and the mechanical pressure (static or dynamic) of a descending astronaut. Comparing fluid-pressure figures and mechanical-pressure figures is really apples-and-oranges, even though you measure them in the same units.
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Post by gonehollywood on Jul 21, 2009 23:37:31 GMT -4
Read the transcripts of the Apollo mission. Not the ones between NASA and ground control, but rather the ones between the Astronauts themselves. Harried to say the least. Not acting. Really scared and relived when it was over. Like you would be on a mission like this.
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Post by drewid on Jul 22, 2009 16:09:06 GMT -4
Read the transcripts of the Apollo mission. Not the ones between NASA and ground control, but rather the ones between the Astronauts themselves. Harried to say the least. Not acting. Really scared and relived when it was over. Like you would be on a mission like this. Armstrongs heartrate went up to 156bpm during the landing. not really surprising with the constant errors the computer was throwing, plus having to land it in semi-auto with somewhere south of 30 seconds of fuel left.
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Post by Kiwi on Jul 22, 2009 16:58:18 GMT -4
...with the constant errors the computer was throwing... It may be just semantics, but I don't think it was throwing errors at all and instead doing an excellent job all the time, especially when, as HBs delight in pointing out as if it actually matters, it was less powerful than a modern cell phone. As Dr Rendezvous freely admits, the fault was his, leaving the rendezvous radar switched on and therefore overloading the cell phone. Errr... computer.
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Post by drewid on Jul 22, 2009 17:26:29 GMT -4
Ok then, overload alarms. Thank goodness for interns with pieces of paper eh?
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