Molten Steel in WTC

[CFLarsen]

22.680 liters?
Wrong to three decimal places Claus.
Methinks your tail hit the "." instead of the "," ?

The "." is not a decimal comma in the civilized world.

 

[Montoya]

[examples of molten aluminum]

In the first one, it's not clear how much ambient light there is, it may be taken inside.
The 2nd one is taken in the dark, not bright daylight.
In the 3rd pic, the crucible is red hot, but the liquid is silvery.
In the 4th one you can't see the aluminum, just the top of the red hot bucket.
In the 5th and 6th one, you can see the same red hot bucket, with silvery aluminum inside.

 

[gumboot]

That's 22.680 liters.

....boooOOOOOMMMM!!!!

Incidently, not long before 9/11 the anti-fire system (not sure what else to call it) on level 5 of WTC7 (with this enormous fuel tank) was cited as being in need of serious addressing (not withstanding the claim by FDNY that the tank itself violated fire codes).

And yet CTers will claim there were no serious fires in WTC7... uh huh.

-Andrew

 

[gumboot]

It's kind of funny that whoever posted that video on You Tube believes the molten steel is evidence of explosives. They cut the video off before they even showed the steel.

Incidently, since the full video shows the digger lifting out the steel as a long column, it's safe to assume it's not molten. I would estimate it's colouring, based on the white balance of the video, to be in the vicinity of "salmon". According to the chart I linked earlier, that's about 900C, well below melting point.

But then again, in LC they refer to "red hot molten steel" so maybe to CTers "molten" is another word for "yellow and really hot".

-Andrew

 

[Reeco]

And yet CTers will claim there were no serious fires in WTC7... uh huh.

-Andrew

How bad does a fire need to be for a CT'er to class it as serious?

 

[Hellbound]

This whole "molten steel produced by explosives" issue is utter and demonstrably false tripe that stems from fundamental ignorance about explosives and how they are used in civilian and military applications. Having worked with a wide assortment of explosives, the only high explosive I am aware of that would melt steel is thermite, but it leaves unmistakable telltale pitting around the cut area. It is normally used in underwater demolitions of steel or metal structures because other approaches (see below) are both less effective and more expensive in that environment. At the same time, detonating thermite can be troublesome. Some CTists suggest that thermite was used to bring down the WTC, based on the presence of molten metal. If that is indeed what was done, I can only marvel at the planners' ineptitude and ignorance in respect of explosives. For the purpose of covering up a demolition, using thermite is just about the penultimate choice one would make short of a team of giggly schoolgirls armed with sledgehammers.

[Pedantic mode/pet peeve]

Pretty much correct in your assessment, except for one thing...

THERMITE IS NOT AN EXPLOSIVE!!!

Sorry, but I've heard that so much it just gets under my skin. It's an incendiary, and can be used to increase damage of certain explosives as well, but it's not explosive in itself.

One other thing on using thermite, it would be hard to cut vertical columns with it, as it burns down. You'd need special equipment (ceramics and similar to contain it) as well as direct access to the columns.

And I'd second your assessment on the poor choice; thermite leaves huge amounts of slag and residue.

Apart from the concealment angle, there are other pragmatic reasons for avoiding thermite. On surface, i.e. in air, there are far more efficient explosive cutting methods that involve dedicated cutting charges. Basically, a specially shaped liner (usually of annealed copper) is given a huge amount of kinetic energy, i.e. enormous velocity in the thousands of metres/sec, by the detonating explosive, and it is the kinetic energy of the resulting slug that cuts the target. The result is a far more accurate and cleaner cut which doesn't involve any melting at all. The slug itself is hot and pliable but hardly molten to a liquid. These cuts have a distinctive look, and traces of the liner material are often visible on them.

Where cutting accuracy is not an issue, e.g. in straight demolitions, less subtlety is afforded by high explosives without the liner adaptation. In this case and for optimal effectiveness, the explosive must have a velocity of detonation (VoD) that exceeds the speed of sound in the material being cut. Basically, the target material fails through being ripped apart as a result of its inability to transmit the shockwave at the incident velocity, i.e. the VoD. No melting is involved. Alternatively, if the VoD is less than the target's sonic speed, far more explosive is required in order to "shear" out a piece of the target by brute force. Again, no melting is involved. Each of these cutting approaches has its own distinct identifying characteristics, and the absence of melting is a result of the brevity of the chemical reaction producing the detonation. The heat produced simply does not transfer into the target quickly enough, and the surrounding air also rapidly dissipates such heat. It is thus purely mechanical failure of the target.

In steel the speed of sound is around 7,200 m/s. Few civilian explosives (RDX-based detonating cord is the only exception that springs immediately to mind) can muster a VoD exceeding about 5,000 m/s. Military plastiques such as C4 on the other hand commonly have VoDs in the 8,000 m/s neighbourhood.

'Luthon64

EXCELLENT!!!!

I have back-up!!!!

I've tried explaining some of this, but my knowledge is more practical and less theoretical. You've done a much better job here of explaining why real explosions aren't the orange fireballs seen in movies and TV (well, unless it's a gas tank).

I was curious about your VoD's, though. I thought modern dynamite was about 21,000 fps, or 7000m/s? My understanding was that most commercial explosives, including things like AN-AL and cratering charges, were about this speed? Admittedly, it's been a while since my studies, so I was wondering if you had any other info on this?

I can check my Engineer's Bible when I get home, as well, see what it has to say.

 

[dubfan]

a team of giggly schoolgirls armed with sledgehammers.

The first time I read this, I thought you wrote "geggly".

I think geggly ones would be worse.

 

[rwguinn]

[Pedantic mode/pet peeve]

Pretty much correct in your assessment, except for one thing...

THERMITE IS NOT AN EXPLOSIVE!!!

Sorry, but I've heard that so much it just gets under my skin. It's an incendiary, and can be used to increase damage of certain explosives as well, but it's not explosive in itself.

One other thing on using thermite, it would be hard to cut vertical columns with it, as it burns down. You'd need special equipment (ceramics and similar to contain it) as well as direct access to the columns.

And I'd second your assessment on the poor choice; thermite leaves huge amounts of slag and residue.



EXCELLENT!!!!

I have back-up!!!!

I've tried explaining some of this, but my knowledge is more practical and less theoretical. You've done a much better job here of explaining why real explosions aren't the orange fireballs seen in movies and TV (well, unless it's a gas tank).

I was curious about your VoD's, though. I thought modern dynamite was about 21,000 fps, or 7000m/s? My understanding was that most commercial explosives, including things like AN-AL and cratering charges, were about this speed? Admittedly, it's been a while since my studies, so I was wondering if you had any other info on this?

I can check my Engineer's Bible when I get home, as well, see what it has to say.

For another demo--se the"Myth Busters" episode where they blew up the Redi-mix truck.
No fireball, no flames. Just a smoke cloud and a disappearing truck.

 

[Arkan_Wolfshade]

For another demo--se the"Myth Busters" episode where they blew up the Redi-mix truck.
No fireball, no flames. Just a smoke cloud and a disappearing truck.

Right-o. You want Hollywood flames? Add gasoline to the experiment. Flame = wasted energy that could be better converted to force.

 

[Hellbound]

For another demo--se the"Myth Busters" episode where they blew up the Redi-mix truck.
No fireball, no flames. Just a smoke cloud and a disappearing truck.

Yep.

A more or less suddenly appearing cloud (until you slow it down on the high-speed camera).

This also puts paid to the idea of people "outrunning" and explosion. Yeah, as if anyone can outrun a shockwave moving at 1600mph.

Arkan: Most film effects use only gasoline for the big, fiery explosions (not just an additive). Things like black powder are used for smokey effects. You generally won't see a true high-explosive detonation...it isn't flashy enough.

 

[Arkan_Wolfshade]

Yep.

A more or less suddenly appearing cloud (until you slow it down on the high-speed camera).

This also puts paid to the idea of people "outrunning" and explosion. Yeah, as if anyone can outrun a shockwave moving at 1600mph.

Arkan: Most film effects use only gasoline for the big, fiery explosions (not just an additive). Things like black powder are used for smokey effects. You generally won't see a true high-explosive detonation...it isn't flashy enough.

Sorry, I wasn't being clear, I meant add gasoline to the Mythbusters' experiment to see the flames.

 

[60hzxtl]

The first time I read this, I thought you wrote "geggly".

I think geggly ones would be worse.

Tell the truth, you miss geggy.

Where's my patch for "mocking" geggy and making him go away?

http://www.internationalskeptics.com/forums/showthread.php?p=1675028#post1675028


20 days since we've seen him.

 

[gumboot]

Arkan: Most film effects use only gasoline for the big, fiery explosions (not just an additive). Things like black powder are used for smokey effects. You generally won't see a true high-explosive detonation...it isn't flashy enough.

I can confirm that. We use big blisters full of petrol. KABOOOM!

And then we shoot it on high speed cameras (which gives the effect of slowing down the explosion in playback). Maybe that's why people think they can outrun them.

The only times we've ever used actual explosives on a film set were to propel any sort of matter around. So if the house needed to "explode" we'd use petrol for the "explosion" and actual explosives to throw bits of house everywhere.

Having said that, knowing the shock wave force and volume of noise you get from a 1000lb bomb going off 1km away, I'm glad we don't use real explosives on set.

And we use squibs for bullet strikes (hence the great sense of irony I get every time a 9/11 CTer mentions the "squibs" coming out of the buildings.)

-Andrew

 

[Anacoluthon64]

[Pedantic mode/pet peeve]

Pretty much correct in your assessment, except for one thing...

THERMITE IS NOT AN EXPLOSIVE!!!

Sorry, but I've heard that so much it just gets under my skin. It's an incendiary, and can be used to increase damage of certain explosives as well, but it's not explosive in itself.

It depends on the packing density, like gunpowder, and to a lesser degree on the addition of small amounts of other reactants, e.g. triethyl amine and nitromethane. If thermite is packed sufficiently tightly, it will detonate, rather than deflagrate. The difference is essentially whether the reaction front moves through the material at sub- or supersonic speed.

One other thing on using thermite, it would be hard to cut vertical columns with it, as it burns down. You'd need special equipment (ceramics and similar to contain it) as well as direct access to the columns.

These difficulties are easy to overcome, according to the CTists.

EXCELLENT!!!!

I have back-up!!!!

I've tried explaining some of this, but my knowledge is more practical and less theoretical. You've done a much better job here of explaining why real explosions aren't the orange fireballs seen in movies and TV (well, unless it's a gas tank).

Thank you, glad you like it. I have, as indicated in my earlier post, some experience in these matters. Those orange fireball explosions one sees in movies are pyrotechnic effects for maximum gawk-factor, and hardly representative of the real thing. They are normally achieved through small gunpowder charges, sometimes immersed in small volumes of a flammable liquid to achieve a more spectacular fireball. In bright daylight, a flash or flame is very rarely visible in a high explosive detonation; in the dark, a bright white and extremely short-lived flash can be seen.

I was curious about your VoD's, though. I thought modern dynamite was about 21,000 fps, or 7000m/s? My understanding was that most commercial explosives, including things like AN-AL and cratering charges, were about this speed? Admittedly, it's been a while since my studies, so I was wondering if you had any other info on this?

I can check my Engineer's Bible when I get home, as well, see what it has to say.

It depends what you mean by "dynamite." In industrial explosives, the original nitroglycerine-based dynagels detonate at around 3,000 m/s. The more modern ammonium nitrate-based slurries are around 4,000 m/s, and certain specialist gels, chiefly AN plus aluminium, close to 5,000 m/s. RDX/PETN boosters have VoDs up to twice as fast, but they are part of the initiation chain. These industrial explosives are used in mining and civil engineering applications. Explosives demolitions crews have their own list of specialised explosives, some of which contain TNT and/or RDX, e.g. Sheetex, where high VoDs are required. The figures are from an explosive manufacturer's handbook, and they generally jibe very well with measurements we ourselves have taken. The highest VoD that I am aware of is a liquid (I forget its name) developed in the former USSR, which under extremely high initial pressure detonates at around 12,000 m/s.

'Luthon64

 

[Hellbound]

It depends what you mean by "dynamite." In industrial explosives, the original nitroglycerine-based dynagels detonate at around 3,000 m/s. The more modern ammonium nitrate-based slurries are around 4,000 m/s, and certain specialist gels, chiefly AN plus aluminium, close to 5,000 m/s. RDX/PETN boosters have VoDs up to twice as fast, but they are part of the initiation chain. These industrial explosives are used in mining and civil engineering applications. Explosives demolitions crews have their own list of specialised explosives, some of which contain TNT and/or RDX, e.g. Sheetex, where high VoDs are required. The figures are from an explosive manufacturer's handbook, and they generally jibe very well with measurements we ourselves have taken. The highest VoD that I am aware of is a liquid (I forget its name) developed in the former USSR, which under extremely high initial pressure detonates at around 12,000 m/s.

'Luthon64

Nifty

So, is there any material that has a speed of sound that's higher than 12,000 mps? Seems that these types of materials could be good for fortified bunkers and such (just speculatin').

 

[CurtC]

Another point which rules out thermite as a cause of the underground heat - underground fires burn a long time because they go only as fast as they can get oxygen seeping in through cracks. Plus, the enclosed conditions hold the heat in so that the fire doesn't go out, it just burns really slowly.

The thermite reaction does not get any oxygen from the air, it just transfers oxygen atoms from iron atoms to aluminum atoms, and all the necessary reactants are already present. Therefore, the thermite reaction happens quickly, whether it's underground or not, and would begin cooling off within seconds. Hot spots for days and weeks is inconsistent with thermite.

 

[Anacoluthon64]

So, is there any material that has a speed of sound that's higher than 12,000 mps? Seems that these types of materials could be good for fortified bunkers and such (just speculatin').

I'm not aware of any such material. Even if it one was able to make one, it wouldn't guarantee against a lower VoD explosive breaching it by the "brute force" mechanism. You'd just need more explosive to do it. It would be more effective to surround the bunker with an evacuated chamber and equip it with retractable access points. Nothing stops a shockwave quite like the complete absence of any medium for it to travel through. Which gives me an idea for testing Sylvia Browne...

'Luthon64

 

[gumboot]

Nifty
So, is there any material that has a speed of sound that's higher than 12,000 mps? Seems that these types of materials could be good for fortified bunkers and such (just speculatin').

From what I can gather the thermobaric weapons such as were used in the cave systems in Afghanistan have the following stats:

"The overpressure within the detonation can reach 430 lbf/in² (3 MPa) and the temperature can be 4500 to 5400°F (2500 to 3000 °C). Outside the cloud the blast wave travels at over 2 mi/s."

source

That's only 3000 mps or so... which is way under.

But it seems to work, so maybe 12,000 mps is overkill?

-Andrew

EDIT: I just realised what you guys were meaning... ignore me...

 

[Hellbound]

From what I can gather the thermobaric weapons such as were used in the cave systems in Afghanistan have the following stats:

"The overpressure within the detonation can reach 430 lbf/in² (3 MPa) and the temperature can be 4500 to 5400°F (2500 to 3000 °C). Outside the cloud the blast wave travels at over 2 mi/s."

source

That's only 3000 mps or so... which is way under.

But it seems to work, so maybe 12,000 mps is overkill?

-Andrew

EDIT: I just realised what you guys were meaning... ignore me...

Well, it works a bit different. As I understand it, it's intended to drill inside the target through a Monroe effect jet (similar to HEAT rounds), using a high-temperature gas to cut through the outer layer, and explode inside the target. So, that's more than a high enough VoD to take care of interior occupants.

Actually, I'm not sure if it uses a Monroe effect or just brute force tunnelling (kinetic impact energy) like AP rounds do.

In any case, in highly reinforced structures you'll have a small outer hole in the actual reinforced area (surrounding dirt will likely be blasted clear), and an inside that looks like Jason and Freddy Kruger had a kegger with a weedwhacker, a sledgehammer, a garden weasel, and an eggbeater.

 

[juryjone]

Nothing stops a shockwave quite like the complete absence of any medium for it to travel through. Which gives me an idea for testing Sylvia Browne...

Had to laugh at that. I can think of many things I'd like to see travel through Sylvia...