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9/11
Mar 17, 2002 4:57:16 GMT -5
Post by ensign in the red shirt on Mar 17, 2002 4:57:16 GMT -5
It is because we too had a zero chance of that happening. Now it can happen anywhere, even where you are. That's why I love these boards - just occasionally you get the piece of wisdom that puts everything in place. Thanks for that. I gotta disagree with your reasons for the burning though. Aviation fuel is very low temperature burning and certainly not hot enough to melt the huge pieces of steel holding up the WTC. Had the plane crashed and burned in the middle of the building as it did the steel would hardly have buckled let alone had a catastrophic failure. There had to be something else that could burn hot enough to ignite the steel. A friend of mine who is a structural engineer ran some calcs through his computer to find out how hot the fire needed to be... The only solution was for some sort of magnesium to be added to the flamable roostertail to give the base fire the extra boost that it needed to reach the required temperature. Here is where it gets spooky. There was enough magnesium in the shell of the aeroplane in the aluminum alloy to boost the fire. However it could only ignite if it was shredded enough - as it was in the shell it would not burn of itself. However, because the plane was flown in to the building at the angle it was, all the vertical structural elements combined to produce an egg-slicer effect that could shred the fuselage enough to burn the magnesium that would boost the jet fuel to sufficient temperatures to melt the structural steel that would eventually lead to the building's collapse. The combination of these elements is vital for the plan to work and yet it would take some pretty sophisticated engineering knowledge to understand this. Bin Laden is an engineer and so could have, conceivably, planned it this way or it could have been unlucky coincidence. The original engineers must be pretty please that their design was so outstandingly successful and that it took such a complicated combination of event to defeat the design. |
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9/11
Mar 17, 2002 5:01:35 GMT -5
Post by ensign in the red shirt on Mar 17, 2002 5:01:35 GMT -5
Ha ha - just checked my post above and noticed that the (American?) spell checker has automatically changed my word "c_o_c_k-tail" to "rooster-tail" ! That's funny!
I've had to edit it again because the same thing happened and yet in edit mode it still displays as "c_o_c_k" without the _ !
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9/11
Mar 17, 2002 7:18:11 GMT -5
Post by Holodoc on Mar 17, 2002 7:18:11 GMT -5
Heh yeah. ;D
But about the fuel, we were told repeatedly about it being the hottest. Maybe they neglected to mention it occurs when setting off a reaction due to exposure to the magnesium in the lining? Anyway, it melted the beams downward from where the plane cut into the building. The building collapsed vertically. Flash diagrams galore on the web.
Why again did they say they couldn't rescue anyone on the observation decks with helicopters?
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9/11
Mar 17, 2002 7:25:48 GMT -5
Post by Christina on Mar 17, 2002 7:25:48 GMT -5
Probably because of the extreme thermals from the fires. It wasn't actually mentioned.
The very thin flame retardant on the steel beams and the core apparently got blasted away by the initial explosions, which is another reason the steel eventually couldn't hold the structure any longer. It seems it was a small miracle it held on for as long as it actually did.
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9/11
Mar 17, 2002 7:31:06 GMT -5
Post by Holodoc on Mar 17, 2002 7:31:06 GMT -5
The heat from the fire melted the beams on down from the inside. That's why they collapsed. Here. |
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9/11
Mar 17, 2002 9:06:24 GMT -5
Post by Dr. Jekyl on Mar 17, 2002 9:06:24 GMT -5
Why again did they say they couldn't rescue anyone on the observation decks with helicopters? I think it was most likely a combination of smoke and thermals that stopped choppers from going up. As to the collapse of the buildings themselves, I think it's going to be very hard to say what the determining factors in the collapse were. I do think, however, that the initial impact did the most damage, particularly to the south tower which fell in on the damaged side. The towers had the guts ripped out of them structuraly, leaving the fires and gravity to do the rest. I knew from the moment that we got clear footage of the first tower that it was going to fall at least partially - it just looked like it was too unstable for the floors above the impact zone to remain upright. Of course, though, I'm not an engineer and am waiting to see what the official investigators say. |
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9/11
Mar 18, 2002 8:13:47 GMT -5
Post by ensign in the red shirt on Mar 18, 2002 8:13:47 GMT -5
Right about the choppers - also, they couldn't believe that the towers stayed up as long as they did.
As for the impact damage, it was a dramatic testament to the quality of the engineers that the towers did not fall over horizontally. They collapsed vertically because the beams melted (lost their structural integrity). A tower over fifty stories high has to have an exo-skeleton, meaning that the structure is supported by a 'girdle' of beams that criss-cross the exterior of the building. This has been used as decoration, most noticeably on the Sears Tower in Chicago, but I'm sure that you will be able to think of other examples. Thus, the planes crashing into the interior columns would have had little or no structural impact because the interior columns cary no weight. The impact of the planes on the exterior of the buildings should have knocked the towers over like bowling pins, but the buildings held.
The towers stayed up for so long because the fire took time to reach the incredible heats required to vapourise the fire-proofing around the steel and then to vapourise the steel itself. Everything will burn, even concrete, given sufficient heat. The brilliance (?) of the design of the collapse was to use heat as the primary weapon, where normally people would assume that the impact would suffice. Or they were just lucky (?).
ps. trust me - if you ever buy a Dell computer pay extra for a decent keyboard...
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9/11
Mar 19, 2002 3:01:25 GMT -5
Post by Peter_Pevensie on Mar 19, 2002 3:01:25 GMT -5
The combination of these elements is vital for the plan to work and yet it would take some pretty sophisticated engineering knowledge to understand this... IIRC, I read a report on one of the major news outlets that said, based on intelligence gathered in Afghanistan, that bin Laden and his associates were surprised that the towers collapsed...they weren't expecting it to happen. |
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9/11
Mar 19, 2002 6:34:10 GMT -5
Post by Holodoc on Mar 19, 2002 6:34:10 GMT -5
IIRC, I read a report on one of the major news outlets that said, based on intelligence gathered in Afghanistan, that bin Laden and his associates were surprised that the towers collapsed...they weren't expecting it to happen. Nothing intelligent about it. It was a translation at the bottom of one of a video as he spoke. He wanted to do damage but didn't expect them to actually collapse. He seemed very impressed at the time. |
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9/11
Mar 20, 2002 5:23:06 GMT -5
Post by ensign in the red shirt on Mar 20, 2002 5:23:06 GMT -5
Well, if he was any good as an engineer he wouldn't have to have become a terrorist, would he?
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9/11
Mar 20, 2002 7:14:23 GMT -5
Post by Holodoc on Mar 20, 2002 7:14:23 GMT -5
Well, if he was any good as an engineer he wouldn't have to have become a terrorist, would he? He'd be a more powerful terrorist. |
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9/11
Mar 20, 2002 9:08:04 GMT -5
Post by Dr. Jekyl on Mar 20, 2002 9:08:04 GMT -5
Well, if he was any good as an engineer he wouldn't have to have become a terrorist, would he? No one *has* to become a terrorist. It's a choice you make of your own free will. |
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9/11
Mar 20, 2002 9:49:04 GMT -5
Post by Peter_Pevensie on Mar 20, 2002 9:49:04 GMT -5
This is starting to read like the script for a bad BBC sitcom.
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9/11
Mar 20, 2002 10:22:24 GMT -5
Post by Dr. Jekyl on Mar 20, 2002 10:22:24 GMT -5
LOL
Well, at least the discussion can't sink to the levels 'The Bill' is at these days. Watched an episode last night and reminded myself exactly why I stopped.
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9/11
Mar 23, 2002 8:22:16 GMT -5
Post by Christina on Mar 23, 2002 8:22:16 GMT -5
The Bill being, of course, a commercial TV police drama / sitcom. Not BBC....  |
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