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#1540
by
Seer
on 30 Jan, 2011 07:40
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Why was the Shuttle crew cabin atmosphere selected to be one atmosphere? Why not half an atmoshere, say? This would be a comprise between the Apollo and Shuttle atmospheric pressures. Does anyone know how much the mass saving would be?
A second question is about the material used on the orbiter. As I understand it, titanium wasn't used for the structure because of scarcity concerns (seems unbelievable to me), but could have the orbiter that replaced Challenger used it?
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#1541
by
DaveS
on 30 Jan, 2011 12:01
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Why was the Shuttle crew cabin atmosphere selected to be one atmosphere? Why not half an atmoshere, say? This would be a comprise between the Apollo and Shuttle atmospheric pressures. Does anyone know how much the mass saving would be?
A second question is about the material used on the orbiter. As I understand it, titanium wasn't used for the structure because of scarcity concerns (seems unbelievable to me), but could have the orbiter that replaced Challenger used it?
The reason for using aluminum over titanium was actually manufacturer experience. Not many airframe manufacturers had experience with large titanium airframes. By using aluminum many more could bid on the orbiter contract.
For the second question: No. Endeavour was assembled from spare parts contracted by NASA during the construction of the last two production orbiters (Discovery and Atlantis).
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#1542
by
Jim
on 30 Jan, 2011 13:38
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Because we live in one atmosphere
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#1543
by
Seer
on 30 Jan, 2011 13:45
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Because we live in one atmosphere
So I take it you don't know.
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#1544
by
Jim
on 30 Jan, 2011 14:27
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Because we live in one atmosphere
So I take it you don't know.
That is exactly the reason and everything falls from it. Habitability, science, international relations, etc
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#1545
by
TFGQ
on 30 Jan, 2011 16:10
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how does the GLS handoff to the RSLS
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#1546
by
Sesquipedalian
on 31 Jan, 2011 00:39
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Because we live in one atmosphere
That's not really a reason. We lived in one atmosphere during Apollo, yet Apollo didn't use one atmosphere.
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#1547
by
Jim
on 31 Jan, 2011 01:09
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Because we live in one atmosphere
That's not really a reason. We lived in one atmosphere during Apollo, yet Apollo didn't use one atmosphere.
[/quote
Yes, it is. Look at what Apollo goals were and look what the shuttle's goals were. Or do I have spell it out?
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#1548
by
brettreds2k
on 31 Jan, 2011 12:18
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I was reading in the article on the front page about the roll out of Discovery, and how once back from her flight she will spend some time in storage in the VAB due to another vechicle will be taking over OPF-3, which it stated could be the X-37. Why would something that small get a facility as large to house and take care of a shuttle?? Was just suprsed to read that today. They could fit a fleet of the X-37's in there...lol.
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#1549
by
ChrisGebhardt
on 31 Jan, 2011 12:56
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I was reading in the article on the front page about the roll out of Discovery, and how once back from her flight she will spend some time in storage in the VAB due to another vechicle will be taking over OPF-3, which it stated could be the X-37. Why would something that small get a facility as large to house and take care of a shuttle?? Was just suprsed to read that today. They could fit a fleet of the X-37's in there...lol.
Similar processing tools and needs. Also, X-37B launches from CCAFS on the Atlas Vs, so it makes sense in many ways to use/modify existing structures at KSC that are no longer needed for Shuttle for use by an "in the family" type vehicle.
Plus, and to be brutally honest here, we no longer need 3 OPFs for Shuttle. We can do just fine with two.
Remember here that we originally only had two OPFs for the first decade of the Shuttle program. OPF-3 was brought online in the early 1990s (IIRC). At that point, we then had 3 OPFs for 4 orbiters. So OPF rotations/juggling is nothing new to the Shuttle program. In fact, it was only after the loss of Columbia 8 years ago that each of the remaining orbiters was given a designated/dedicated OPF following Discovery's and Endeavour's OMDPs at Kennedy.
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#1550
by
padrat
on 31 Jan, 2011 13:30
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Hmm... Must be a new member. You'll learn, lol.
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#1551
by
Naito
on 31 Jan, 2011 14:18
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Because we live in one atmosphere
So I take it you don't know.
That is exactly the reason and everything falls from it. Habitability, science, international relations, etc
I think what Jim means to say is that the goals of the two different programs dictated why the pressures were set this way.
In Apollo, the goal was simply to get to the moon via whatever means possible. The astronauts were all hardened ex-military or test pilots and stuff, as such they were used to tolerating extreme conditions and it was just part of getting the job done. They NEEDed the lower pressure to make the cabin lighter and get to the moon and back.
In shuttle, the original goal was to be able to bring up any old regular joe to space. It was supposed to be a shirt-sleeve environment just like an airliner. So launch G forces were limited to 3 to make it more comfortable, whereas I believe Saturn V launches were upwards of 6Gs. 3G is like a fast roller coaster, 6G and most untrained people would probably pass out. Same goes for the cabin pressure, they tried to keep it as similar to ground level as possible so that it would be as familiar and "normal" an environment as possible.
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#1552
by
Jorge
on 31 Jan, 2011 16:23
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Because we live in one atmosphere
So I take it you don't know.
That is exactly the reason and everything falls from it. Habitability, science, international relations, etc
I think what Jim means to say is that the goals of the two different programs dictated why the pressures were set this way.
In Apollo, the goal was simply to get to the moon via whatever means possible. The astronauts were all hardened ex-military or test pilots and stuff, as such they were used to tolerating extreme conditions and it was just part of getting the job done. They NEEDed the lower pressure to make the cabin lighter and get to the moon and back.
In shuttle, the original goal was to be able to bring up any old regular joe to space. It was supposed to be a shirt-sleeve environment just like an airliner. So launch G forces were limited to 3 to make it more comfortable, whereas I believe Saturn V launches were upwards of 6Gs. 3G is like a fast roller coaster, 6G and most untrained people would probably pass out. Same goes for the cabin pressure, they tried to keep it as similar to ground level as possible so that it would be as familiar and "normal" an environment as possible.
Not just the crew, the materials. Apollo required special non-flammable materials everywhere due to the fire risk in the pure O2 atmosphere. The program desire to be able to carry "off-the-shelf" equipment aboard shuttle dictated air. There are many materials flown on the shuttle that could never have been carried aboard Apollo due to the fire risk.
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#1553
by
alexw
on 31 Jan, 2011 17:32
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A second question is about the material used on the orbiter. As I understand it, titanium wasn't used for the structure because of scarcity concerns (seems unbelievable to me), but could have the orbiter that replaced Challenger used it?
AIUI, most of the world titanium deposits (at least as available in the 1960s & 70s) were in the Soviet Union. I've read that the SR-71 was in large part built with Soviet titanium, for which the CIA needed to set up a series of front companies to contrive the purchases. Titanium metalworking and welding was also in its infancy.
Concorde, which was approximately contemporary to Shuttle, went with an aluminum body, thereby limiting its max speed to around Mach 2.2. Even the Soviets went with stainless steel instead of titanium (on cost grounds?) for the Mig-25.
-Alex
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#1554
by
agman25
on 01 Feb, 2011 20:02
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A pure O2 question. Does it make EVA's easier if the spacecraft has a pure O2 atmosphere?
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#1555
by
Lee Jay
on 01 Feb, 2011 20:09
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AIUI, most of the world titanium deposits (at least as available in the 1960s & 70s) were in the Soviet Union. I've read that the SR-71 was in large part built with Soviet titanium, for which the CIA needed to set up a series of front companies to contrive the purchases. Titanium metalworking and welding was also in its infancy.
Titanium is exceptionally common. It's what gives white paint its whiteness. The problem with Titanium isn't digging it up, it's processing it into a a usable metal - much the same as Aluminum.
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#1556
by
MP99
on 01 Feb, 2011 20:50
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Because we live in one atmosphere
So I take it you don't know.
That is exactly the reason and everything falls from it. Habitability, science, international relations, etc
I think what Jim means to say is that the goals of the two different programs dictated why the pressures were set this way.
In Apollo, the goal was simply to get to the moon via whatever means possible. The astronauts were all hardened ex-military or test pilots and stuff, as such they were used to tolerating extreme conditions and it was just part of getting the job done. They NEEDed the lower pressure to make the cabin lighter and get to the moon and back.
In shuttle, the original goal was to be able to bring up any old regular joe to space. It was supposed to be a shirt-sleeve environment just like an airliner.
Bad analogy. Airliners aren't maintained at sea level air pressure! (But people don't live in airliners for many days at a time, either.)
However, I do wonder whether there would have been any really significant mass saving to using an Apollo-type atmosphere.
cheers, Martin
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#1557
by
MP99
on 01 Feb, 2011 20:53
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Hmm... Must be a new member. You'll learn, lol.
Yes, but Jim wears one-word answers as a badge of honour. I think he might be interested if someone found a way to post partial syllables or reduce the pixel count on that one word. (It's just an affectionate joke, Jim).
Actually, I've long suspected that Jim types most of his responses on a Blackberry or similar, and I wouldn't want to type long responses on that sort of keyboard.
Nevertheless, this sometimes provides an opportunity for someone with more time on their hands to backup Jim's encyclopaedic knowledge (the Jimopedia?) with a greater depth of insight.
cheers, Martin
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#1558
by
alexw
on 01 Feb, 2011 22:17
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I suspect that it's mostly a function of time. Jim is a prolific poster, and NSF is always fortunate to have someone of encyclopedic knowledge willing to answer so many questions here. Presumably, he has plenty of work to do, and his personal compromise is brutal efficiency against politeness.
The more interesting posts can be the long ones -- when Jim, or Dr. Elias, or Blackstar (to mention just a few) are willing to go into some lengths, that suggests a subject of personal interest.
-Alex
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#1559
by
Jim
on 01 Feb, 2011 23:33
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The avionics are also aircooled.