Armed Polite Society
Main Forums => The Roundtable => Topic started by: RevDisk on September 20, 2016, 03:45:00 PM
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http://www.popularmechanics.com/space/satellites/a22936/tiangong-falling-to-earth/
http://news.xinhuanet.com/english/2016-09/14/c_135687885_2.htm
The Tiangong-1 is China's first 'space station'. The Tiangong-1 is an oversized Shenzhou, which is a stretched Soyuz. They admitted that they couldn't tell where it would land. Which virtually certainly means they don't have control anymore. They did say a couple months ago that they disabled data service, but that was component monitoring. Tiangong-2 was already launched.
OTOH, they have more of a manned space program than we do so.... Can't give too much smack talk.
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So Trump will have to build a wall and a roof?
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[tinfoil] This how it will start. Uncontrolled re-entry my hairy butt. They'll crash the damn thing in the middle of NYC and claim no responsibility. Then, while we're all busy with that they'll invade the west coast and annex California, which in retrospect might not be so bad after all. [tinfoil]
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[tinfoil] This how it will start. Uncontrolled re-entry my hairy butt. They'll crash the damn thing in the middle of NYC and claim no responsibility. Then, while we're all busy with that they'll invade the west coast and annex California, which in retrospect might not be so bad after all. [tinfoil]
I'm good with that.
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[tinfoil] This how it will start. Uncontrolled re-entry my hairy butt. They'll crash the damn thing in the middle of NYC and claim no responsibility. Then, while we're all busy with that they'll invade the west coast and annex California, which in retrospect might not be so bad after all. [tinfoil]
So when President Donald builds his wall along the southern border of Arizona, he can just take a right turn to the north when the wall gets to Los Algodones ...
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[tinfoil] This how it will start. Uncontrolled re-entry my hairy butt. They'll crash the damn thing in the middle of NYC and claim no responsibility. Then, while we're all busy with that they'll invade the west coast and annex California, which in retrospect might not be so bad after all. [tinfoil]
Uh, you do know it's 34.1 ft by 11 ft and only about 9 tons? Even if it was squarely aimed at NYC and survived re-entry (without guidance), it'd do less damage than an out of control dump truck.
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Uh, you do know it's 34.1 ft by 11 ft and only about 9 tons? Even if it was squarely aimed at NYC and survived re-entry (without guidance), it'd do less damage than an out of control dump truck.
Yah. A few of the tougher chunks, like a titanium pressurization tank, and beefier fragments of the structure will survive, and fall at roughly terminal velocity as if they were dropped from a plane.
And still 90% odds or so it falls in ocean, wilderness, or a farm field.
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Uh, you do know it's 34.1 ft by 11 ft and only about 9 tons? Even if it was squarely aimed at NYC and survived re-entry (without guidance), it'd do less damage than an out of control dump truck.
It's made in China. Probably coated in something horribly toxic because it was cheaper than Krylon.
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[tinfoil] This how it will start. Uncontrolled re-entry my hairy butt. They'll crash the damn thing in the middle of NYC and claim no responsibility. Then, while we're all busy with that they'll invade the west coast and annex California, which in retrospect might not be so bad after all. [tinfoil]
My devious, paranoid, evil brain was composing something to this effect too. But I too wondered about how much physical damage it could do. Apart from any nuclear materials on board.
But of course there's a staff meeting going on right now in Pentagon Meeting Room E-215 regarding this. The betting seems to favor 39°50′N 98°35′W as the place they'll plunk it down and pretend it was all innocent and accidental-like.
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Yah. A few of the tougher chunks, like a titanium pressurization tank, and beefier fragments of the structure will survive, and fall at roughly terminal velocity as if they were dropped from a plane.
And still 90% odds or so it falls in ocean, wilderness, or a farm field.
Even a titanium tank is gonna have a hard time staying intact through atmo. Even still, like you said, much much higher chance of hitting ocean or middle of nowhere than people, buildings, etc.
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[tinfoil] This how it will start. Uncontrolled re-entry my hairy butt. They'll crash the damn thing in the middle of NYC and claim no responsibility. Then, while we're all busy with that they'll invade the west coast and annex California, which in retrospect might not be so bad after all. [tinfoil]
I'm good with that.
And we should threaten instant nuclear retaliation if they refuse to take NYC and DC too.....
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Even a titanium tank is gonna have a hard time staying intact through atmo. Even still, like you said, much much higher chance of hitting ocean or middle of nowhere than people, buildings, etc.
Due to the tough material, round shape, and low mass (either empty, or they vent as the connecting pipes or valves burn off) , they're the most commonly found pieces of intact space debris. Even sometimes carbon fiber/composite ones land largely intact.
https://www.google.com/search?q=titanium+tank+found+space&safe=off&source=lnms&tbm=isch&sa=X&ved=0ahUKEwi8zK6Sp6HPAhWE3YMKHbwnAuQQ_AUICCgB&biw=1366&bih=629#imgrc=DgRS60VDjNuUdM%3A
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But of course there's a staff meeting going on right now in Pentagon Meeting Room E-215 regarding this. The betting seems to favor 39°50′N 98°35′W as the place they'll plunk it down and pretend it was all innocent and accidental-like.
I wonder if they'll thank the Clintons for the guidance system?
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I guess I didn't see why the station was having trouble in the first place. Just age?
(https://thechive.files.wordpress.com/2016/09/giphy6.gif?w=240)
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Even a titanium tank is gonna have a hard time staying intact through atmo. Even still, like you said, much much higher chance of hitting ocean or middle of nowhere than people, buildings, etc.
You'd be surprised.
Due to the tough material, round shape, and low mass (either empty, or they vent as the connecting pipes or valves burn off) , they're the most commonly found pieces of intact space debris. Even sometimes carbon fiber/composite ones land largely intact.
https://www.google.com/search?q=titanium+tank+found+space&safe=off&source=lnms&tbm=isch&sa=X&ved=0ahUKEwi8zK6Sp6HPAhWE3YMKHbwnAuQQ_AUICCgB&biw=1366&bih=629#imgrc=DgRS60VDjNuUdM%3A
AJ is correct.
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I guess I didn't see why the station was having trouble in the first place. Just age?
(https://thechive.files.wordpress.com/2016/09/giphy6.gif?w=240)
OH YE-
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Come to think of it, just venting a pressure vessel after the valves and other plumbing burns off would keep it cooler on the way down, no? And it wouldn't actually be exposed to atmospheric friction until the rest of the station burned away around it, I reckon.
So I can see them coming down intact if everything is "just so."
Terry
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Come to think of it, just venting a pressure vessel after the valves and other plumbing burns off would keep it cooler on the way down, no? And it wouldn't actually be exposed to atmospheric friction until the rest of the station burned away around it, I reckon.
So I can see them coming down intact if everything is "just so."
Terry
Not really/it depends re: the depressurization.
Yes on the other part, but the station would likely mechanically separate before it burned away.
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Come to think of it, just venting a pressure vessel after the valves and other plumbing burns off would keep it cooler on the way down, no? And it wouldn't actually be exposed to atmospheric friction until the rest of the station burned away around it, I reckon.
So I can see them coming down intact if everything is "just so."
Terry
Pressurized with what? Oxygen? BOOM! Only small chunks remain. What inert gas would it be pressurized with?
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Pressurized with what? Oxygen? BOOM! Only small chunks remain. What inert gas would it be pressurized with?
Helium. The smaller spherical tanks might be for Hydrazine or other hypergolic/binary propellants for RCS, but often it's a helium tank used to pressurize the fuel and drive it out of it's tank and fill the growing void in the tank to maintain pressure, and it's structural integrity too.
The high thrust of takeoff can't be managed in large rockets simply by a helium pressurization system to drive the oxidizer and fuel to the combustion chamber and rocket nozzle, they use turbopumps for that of course, but they still use helium pressurization to back-fill the tanks etc. keep everything moving in the right direction and whatnot.
The smaller RCS systems, and lower powered orbital maneuvering thrusters, and station-keeping might be entirely pressure-fed with helium.
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Helium. The smaller spherical tanks might be for Hydrazine or other hypergolic/binary propellants for RCS, but often it's a helium tank used to pressurize the fuel and drive it out of it's tank and fill the growing void in the tank to maintain pressure, and it's structural integrity too.
The high thrust of takeoff can't be managed in large rockets simply by a helium pressurization system to drive the oxidizer and fuel to the combustion chamber and rocket nozzle, they use turbopumps for that of course, but they still use helium pressurization to back-fill the tanks etc. keep everything moving in the right direction and whatnot.
The smaller RCS systems, and lower powered orbital maneuvering thrusters, and station-keeping might be entirely pressure-fed with helium.
Yup, and unlike most other gases, helium heats up when expanded through an orifice (it's Joule-Thomson coefficient opposite of things like nitrogen, oxygen, argon, etc...at least when starting at any reasonable temps)
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I didn't know that, cool. Thanks for the info.
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Helium is weird stuff.
However, I did not specify helium in terms of cooling the pressure vessel by venting. I have no idea of what kind of balance there might be with respect to the heat input from atmospheric friction versus the amount of cooling by venting, and no way to calculate it with multivariate inputs.
I just mentioned cooling by venting as a possible variable in explaining why pressure vessels sometimes make it all the way to the ground, with the nature of the gas unspecified.
(And I'm surprised nobody seems to have picked up on the "target coordinates" I mentioned above: 39°50′N 98°35′W.)
Terry
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Center X center of the US. Thus wondering if the Chinese would thank the Clintons for a way to do so accurately.
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Helium is weird stuff.
However, I did not specify helium in terms of cooling the pressure vessel by venting. I have no idea of what kind of balance there might be with respect to the heat input from atmospheric friction versus the amount of cooling by venting, and no way to calculate it with multivariate inputs.
I just mentioned cooling by venting as a possible variable in explaining why pressure vessels sometimes make it all the way to the ground, with the nature of the gas unspecified.
(And I'm surprised nobody seems to have picked up on the "target coordinates" I mentioned above: 39°50′N 98°35′W.)
Terry
What I meant was venting will only cool the tank if it isn't helium, hydrogen, or neon (the last one is IIRC). If it were hydrazine or other liquid, then yes, due to phase change.
But the reason they make it to the ground is due to low ballistic coefficient.
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I'm thinking they are using phosgene and they will set the nuke off in the atmosphere at 230's coordinates
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Well, by "nuclear components," I meant things like nuclear power supplies, not necessarily explosive devices.
I assume by low ballistic coefficient, birdman means "smallish, low-density, round objects."
I'll go along with that in the full set of variables involved.
Like throwing a balled-up paper wad across the room, as opposed to throwing a marble of the same weight.
And yes, those are the coordinates of the geographic center of the contiguous United States.
At first glance, they look like the coordinates of a random place, but have more significance than that.
The "center" is in South Dakota, if you include Hawaii and Alaska.
https://en.wikipedia.org/wiki/Geographic_center_of_the_contiguous_United_States
I found this amusing:
Method of measurement[edit]
In 1918, the Coast and Geodetic Survey found this location by balancing on a point a cardboard cutout shaped like the U.S.[5] Incredibly, this method was accurate to within 20 miles, but while the Geodetic Survey no longer endorses any location as the center of the U.S., the identification of Lebanon, Kansas has remained.
That's better than 1% accuracy, figuring 20/3000 miles.
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That's better than 1% accuracy, figuring 20/3000 miles.
There you go with your 1% cis-privilege, geo-shaming other less coordinate fortunate locations.
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I assume by low ballistic coefficient, birdman means "smallish, low-density, round objects."
Ballistic coefficient is Mass/(CdA).
Think of it as mass per unit drag.
One can have:
small, high BC objects (rifle bullets)
Small, low BC objects (pistol bullets)
(Both of the above with the same mass)
Large high BC objects (ICBM RV's)
Large low BC objects (spheres or aero-stable blunt bodies)
(Both of the above with the same mass)
Basically, terminal velocity is a direct function of BC.
A high BC object will have a lower peak heating rate as it slows down substantially in the upper atmosphere, while a high BC object will be going faster, lower, and thus have a higher peak heating.
So as long as you make something "fluffy" it doesn't hit that high of an acceleration or heating. This is why things like an inflatable ballute can be used for re-entry. Get the BC low enough and you can keep the heating rate low and level out the acceleration if it's a shallow trajectory.
Conversely, a very streamlined, 20cm dia X 20m long (12 tons) tungsten telephone pole would have a hypersonic terminal velocity of close to 2.5-3km/s, and would actually -speed up- from orbital velocity until it hit about 60-70,000ft, even if vertical!
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Basically, terminal velocity is a direct function of BC.
A high low BC object will have a lower peak heating rate as it slows down substantially in the upper atmosphere, while a high BC object will be going faster, lower, and thus have a higher peak heating.
Correction! Thanks 230RN for pointing my error out. You win 1 birdman point =)
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Thanks ! That leaves me with only -17 birdman points to eliminate.