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Originally Posted by Raghar
Considering plates have a large surface area, they have much higher ability to absorb heat from reentry than iron spheres.
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Most of the heat is going to go to the leading edge, so you're better off looking at the ratio of the surface area of that facing with the total volume.
Quote:
Originally Posted by Raghar
81 tonnes is more likely.
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A specific gravity of 2.7 translates to 2700 kg/m^3. So that would only be true if they were 3mm thick plates.
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Originally Posted by LoweGear
My point is that if an object designed and prepped for reentry can still burn up, what more an object that isn't?
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It's worth noting that Columbia was both going much faster (around Mach 20), and that it was spending far more time in the atmosphere.
Quote:
Originally Posted by Tsukou
I misread one of your statements, involving your assumption of the plates, and then I'm going to assume you were talking about the amount of stress the plates have, rather then the actual weight of them. And you said yourself, the distance between it's initial fall, and the velocity of which it hits the ground isn't going to be very different, and this is all ready at 100kms max.
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It's not 100km max. The lower limit should be at 10,000km.
Quote:
Originally Posted by Tsukou
Once again, tell me how you get this, I realize meteorites can do this, but not only do they not produce as much heat because of the lack of surface area, but the material they are made of is also extremely heat resistant, also, these pieces are usually so small, that the threat they pose, isn't as great, as these gigantic plates, which will burn up..
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They also have a much higher initial velocity, and they tend to spend much more time in the atmosphere, so they get heated up by more than 5000K. By the way, nickel-iron meteroites have a
lower boiling point than carbon nanotubes.
Quote:
Originally Posted by Tsukou
Yes, if I was a super computer, able to calculate where it'll be at any given time, within fractions of a second, being within a distance away from it, to neglect reaction time, eg: .16 seconds away at least. So even if it was 3 seconds from the target zone, I don't see how anyone could miss.
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And yet we see easier shots miss all the time.
Quote:
Originally Posted by Tsukou
Ok, for these, I will do the calculations, at 1000 cross sectional, 8100 kgs(not tons)
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Please justify these numbers. I'm talking about aluminum, and a 8100kg block of aluminum has a volume of only 3m^3.
Quote:
Originally Posted by Tsukou
It isn't as hot as you assume it to be, a metal in space, right outside the earth will possibly get 400 K, on the moon, when sun hits it, it gets about 300 K i believe.. can't remember. The difference between that and thousands of K I don't think you're understanding. It is unnecessary to make a structure to withstand the temperature for reentry..
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Where did I write that it was necessary for a plate to be design to withstand the temperature of reentry? My point was that despite the heat, only a small portion of its mass would have been burned off. This is due to a combination of factors: the short exposure to the high temperatures, the relative heat resistance of the material, and by far the most important - the sheer size of the plate.
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Originally Posted by Krono
So why do you think that the shielding on the elevator is more heat resistant than meteors? Meteors in the vicinity of earth withstand the heat from solar radiation just fine, and they still burn up and break apart harmlessly upon entering earth's atmosphere.
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It's a bit of selection bias. Complex electronics and structures suffer much more from adverse temperatures than lumps of rock. And remember that the larger meteorites
don't completely burn up - however, most of meteors are of the much smaller variety.
Quote:
Originally Posted by Krono
I'm almost positive the orbital mechanics would mean that almost all material would fall to the west of the tower, not straight down. Afterall, the earth's surface is still turning.
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Earth's rotation won't have much of an effect since the entire elevator rotates at the same rate -
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Originally Posted by tanqexe
I don't really get why there's all this hubbub about accuracy of shots. There were so many panels raining down that it was a veritable turkey shoot. If you miss the shot intended for one panel, chances are there's another panel farther away that would take the blast. With enough fire support saturating the air space, you can get good protective coverage from the debris for a small area. CIWS phalanx on ships act on similar principle by lobbing loads of rounds at anti-ship missiles with the aid of a targeting sensor system.
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It's sort of the opposite of that problem. If there's enough density of falling plates, then there would be little chance of hitting a significant portion of them. And then there's the problem that most of the mass and velocity of the plates will remain, even after they've been shattered.
In the case of CIWS, they are becoming increasingly incapable of stopping new generations of hypersonic missiles because of a lack of reaction time, and the sheer momentum of the missiles.
My goal for bringing up accuracy is to point out the impossibility of aiming at, and hitting any one particular plate.
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Originally Posted by kiramuro
Don't get me wrong I think doing physics based on visual imagery of a fictional show is rather "counter productive " but I have to admit that sometimes I am guilty of it myself.
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Agreed, except that the point is to have fun. If I didn't find it fun to discuss this kind of thing, then it'd really be pointless.
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Originally Posted by kiramuro
Since you brought it up.. yes imagination is good but technological advances didn't come about because of obsession with a fictional work. There is a difference between obsession with the work itself and the subject matter described by the work. Oberth didn't become a great rocket scientist because he wrote a detail analysis of Jules Verne's Moon books.
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Actually, there were a number of scientists who entered the field because of an interest in science fiction - I think that the most obvious example is Star Trek. There are also some proposals that first surfaced in fiction before they showed up in real life (Clarke's communication satellites spring to mind). Of course it's much more unlikely now because most of the workable ideas are already being explored, but it was a lot more common a few decades ago.
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Originally Posted by blitz1/2
Have you people wondered what will happen if we stuck a SF with Meteor (earth capable) in the collapsing elevator situation?
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It wouldn't help much because the fundamental problems still remain.
