The thread is split off from
Jones New Paper: Microspheres and Temperatures
Basically, I had suggested a low velocity blast of less than 100 mph, from a tempered thermobaric, as source of the pulverisation. Some people on that thread keep missing the point that I am not positing this as a source of the columns' destruction, but rather pulverization of most of the other stuff. Besides the visuals of the buildings as they were coming down, recall reports of not finding a piece of a phone bigger than the touchpad, or the scarcity of photos that show even a squashed computer screen or shard of glass.
There was some back and forth on this, which you can read in the other thread. Mr. Mackey's last post to me on the subject is:
My answer, on this brand spanking new thread, is:
Well, .17 psi overpressure isn't going to pulverize much of anything. It's not entirely clear to me, though, whether the .17 psi represents the effect of a single plane wave, or a continuous train of waves. Do you know which it is? And if the latter, how dense can these wave fronts be, and will the effects be additive, in some sense?
Thanks to your post, I spent time - too much, it seems, yet still not enough - googling around for info on deflagrations, thermite, solid propellants, etc. Basically, I am trying to get a sense of whether or not 'mild' controlled explosions can 'shoot' ferrous by-products subsonically at hundreds of mph, yet still not create a purely gaseous pressure wave that exceeds 170 mph. (170 mph limit for a WTC window is guesstimated from http://www.litchfield-group.co.uk/sheerframe/news/walling-index.asp?story=20060413 ) I assume this would not be from a thermobaric, since dispersing the reactants first would make for more of a mismatch between a blast wave containing ferrous molecules ( about 3,000x as dense as air molecules ), and a concomittant gaseous pressure wave. We either want an air pressure wave which never exceeds 170 mph (or whatever the correct limit is for the WTC windows), or else one which does, but the trailing particle front is close enough, and moving fast enough, so that we can't distinguish it as a separate event. I think this argues for point sources, not dispersed ones. (Hence, again, we're not talking about thermobarics.)
Now, consider:
(caveat emptor-I haven't done much double checking of my calculations. However, the Giants are going to beat the Patriots, and the game is starting in only 20 minutes. First things first!)
A .22 Long rifle takes a 40 grain bullet, with muzzle velocity 1255 ft/s, or 2.6 gram and 382 m/s, giving a momentum of roughly .99 kg-m/s
So, 10,000 bullets would give us a momentum of 9900 kg-m/s
a mole of Fe203 + 2 moles of Al will weigh 210 grams, and have a heat energy of 853 kJ
If .5% of this can be utilized to impart kinetic energy to the reactants (via rapid heating of gases), then we can compute the speed from
.005 * 853,000 = .5 * .21 * v^^2
v = sqrt ( 853,000 )
201 m/s = 449 mph < 770 mph = speed of sound in air
This would represent a momentum of .21 kg * 201 m/s = 42.21 kg-m/s.
To get the equivalent momentum of 10K bullets, you would need (9900 / 42.21) * .21 kg, or about 50 kg of 'exploding thermite'.
This calculation is suggestive, at best. I've not made any attempt to rigorously determine what gas speeds would be associated with a thermite explosion with a .5% conversion efficiency to KE. I also have no idea how quickly the thermite would heat up. Presumably, you want it to heat up quickly, so that it can pulverize via burning through, not just kinetic energy. Perhaps we need a sophisticated nano-thermite, not regular thermite.
Recall that the red-gray chips have a red side (that Professor Jones believes is thermite) of thickness 40 microns. This is about equal to the radius the "preferred" sized aluminum particle in a solid fueled rocket engine, if I read the following correctly: http://dspace.dsto.defence.gov.au/dspace/bitstream/1947/3835/1/DSTO-GD-0344 PR.pdf
Counter-arguments that readily come to mind are: 1) I would expect liquid metal droplets to get deformed as they slam into any solids. Thus, I would expect most of them not to be spherical. 2) I would think that there would be ubiquitous mottling. Just like I don't believe that a column punching through a floor element will cause it to disintegrate far from it's impact area, I also wouldn't expect a tiny piece of metal traveling at, say, 250 mph to destroy a structure many times it's surface area. Of course, if you had millions of them, that might be another story.
Hmmm. I was going to sign off, but this is too tempting.
Well, I recently came across the density of rust. It is 4 g / cm3. If we pretend that one of Professor Jones' chip (red side) has a similar density, then know that there would be ~ (10^^-6 m^^3/ .004 kg) / {(.001 m)^^2 * 4x10^^-5 m} chips, or about 6 million.
At 44,000 sq ft per floor in a WTC tower, this works out to about 136 thermite chip-projectiles per square foot.
Jones New Paper: Microspheres and Temperatures
Basically, I had suggested a low velocity blast of less than 100 mph, from a tempered thermobaric, as source of the pulverisation. Some people on that thread keep missing the point that I am not positing this as a source of the columns' destruction, but rather pulverization of most of the other stuff. Besides the visuals of the buildings as they were coming down, recall reports of not finding a piece of a phone bigger than the touchpad, or the scarcity of photos that show even a squashed computer screen or shard of glass.
There was some back and forth on this, which you can read in the other thread. Mr. Mackey's last post to me on the subject is:
Hokey smokes!!
You're going to get Stundied for that one. I'm not going to do it, and I don't participate in teh Stundies, I'm just warning you.
Either you're playing dumb to gain some leverage off my sense of charity (not a bad strategy) or you're even more confused than I could have imagined. But I'll try to help. We have to go back to Square One for this.
There is, by definition, no possible explosive of any kind with such a low blast front speed. Remember what we're talking about, here. The "blast front" you are describing is a pressure wave. In the case of a high explosive, like TNT or RDX, the "blast front" is a shock wave, and is therefore supersonic. The speed depends on a lot of things but will exceed 340 m/s, or 770 MPH to use your choice of units. A low explosive, like black powder, does not generate a shock wave, instead generating a possibly large in amplitude, but not sharp, pressure wave. This wave moves at the speed of sound, 770 MPH.
The sound speed is the minimum speed of the "blast front." There is no explosive, not of any kind, that will go a mere 100 MPH.
To get such a slow speed, you're not talking about explosives any more, nor a "blast front." That kind of speed, being at Mach numbers of < 0.15, is definitely in the regime known as "incompressible flow." Since we're not setting off this strange device in a sealed chamber, the static air pressure remains constant. The only forces are kinetic, i.e. what "pressure" you feel is strictly due to the air's velocity. Your device will simulate the effect of a 100 MPH gust of wind.
Because the force is purely kinetic, we can calculate the actual felt pressure directly -- it only depends on speed in this case. Using the Bernoulli equation, the felt pressure is equal to ρ v2 / 2, where ρ is the density of air, and v is the speed of the air at infinity.
In your case, the speed is your mandated 100 MPH (about 45 m/s), and air density is about 1.2 kg / m3. The felt pressure then works out to about 1200 kg m2 / (s2 m3), or 1.2 kPa. In archaic units, this is 0.17 PSI.
That's it. Not even enough to break windows. Abandon this hypothesis now.
The only way you can reconcile such a slow airflow speed with structural damage is if your mystery device is in mechanical contact with the structure -- rather than transmit a "blast wave," it just pushes on the columns. That, of course, can be done as slow as you wish.
So rather than focus on hyperbaric explosives, you should instead start looking into hypotheses involving, for instance, expanding foam, or (dare I say) collapse of the upper structure.
If you need still further help, as I imagine you do, please start another thread. This is long overdue.
My answer, on this brand spanking new thread, is:
Well, .17 psi overpressure isn't going to pulverize much of anything. It's not entirely clear to me, though, whether the .17 psi represents the effect of a single plane wave, or a continuous train of waves. Do you know which it is? And if the latter, how dense can these wave fronts be, and will the effects be additive, in some sense?
Thanks to your post, I spent time - too much, it seems, yet still not enough - googling around for info on deflagrations, thermite, solid propellants, etc. Basically, I am trying to get a sense of whether or not 'mild' controlled explosions can 'shoot' ferrous by-products subsonically at hundreds of mph, yet still not create a purely gaseous pressure wave that exceeds 170 mph. (170 mph limit for a WTC window is guesstimated from http://www.litchfield-group.co.uk/sheerframe/news/walling-index.asp?story=20060413 ) I assume this would not be from a thermobaric, since dispersing the reactants first would make for more of a mismatch between a blast wave containing ferrous molecules ( about 3,000x as dense as air molecules ), and a concomittant gaseous pressure wave. We either want an air pressure wave which never exceeds 170 mph (or whatever the correct limit is for the WTC windows), or else one which does, but the trailing particle front is close enough, and moving fast enough, so that we can't distinguish it as a separate event. I think this argues for point sources, not dispersed ones. (Hence, again, we're not talking about thermobarics.)
Now, consider:
(caveat emptor-I haven't done much double checking of my calculations. However, the Giants are going to beat the Patriots, and the game is starting in only 20 minutes. First things first!)
A .22 Long rifle takes a 40 grain bullet, with muzzle velocity 1255 ft/s, or 2.6 gram and 382 m/s, giving a momentum of roughly .99 kg-m/s
So, 10,000 bullets would give us a momentum of 9900 kg-m/s
a mole of Fe203 + 2 moles of Al will weigh 210 grams, and have a heat energy of 853 kJ
If .5% of this can be utilized to impart kinetic energy to the reactants (via rapid heating of gases), then we can compute the speed from
.005 * 853,000 = .5 * .21 * v^^2
v = sqrt ( 853,000 )
201 m/s = 449 mph < 770 mph = speed of sound in air
This would represent a momentum of .21 kg * 201 m/s = 42.21 kg-m/s.
To get the equivalent momentum of 10K bullets, you would need (9900 / 42.21) * .21 kg, or about 50 kg of 'exploding thermite'.
This calculation is suggestive, at best. I've not made any attempt to rigorously determine what gas speeds would be associated with a thermite explosion with a .5% conversion efficiency to KE. I also have no idea how quickly the thermite would heat up. Presumably, you want it to heat up quickly, so that it can pulverize via burning through, not just kinetic energy. Perhaps we need a sophisticated nano-thermite, not regular thermite.
Recall that the red-gray chips have a red side (that Professor Jones believes is thermite) of thickness 40 microns. This is about equal to the radius the "preferred" sized aluminum particle in a solid fueled rocket engine, if I read the following correctly: http://dspace.dsto.defence.gov.au/dspace/bitstream/1947/3835/1/DSTO-GD-0344 PR.pdf
Counter-arguments that readily come to mind are: 1) I would expect liquid metal droplets to get deformed as they slam into any solids. Thus, I would expect most of them not to be spherical. 2) I would think that there would be ubiquitous mottling. Just like I don't believe that a column punching through a floor element will cause it to disintegrate far from it's impact area, I also wouldn't expect a tiny piece of metal traveling at, say, 250 mph to destroy a structure many times it's surface area. Of course, if you had millions of them, that might be another story.
Hmmm. I was going to sign off, but this is too tempting.
Well, I recently came across the density of rust. It is 4 g / cm3. If we pretend that one of Professor Jones' chip (red side) has a similar density, then know that there would be ~ (10^^-6 m^^3/ .004 kg) / {(.001 m)^^2 * 4x10^^-5 m} chips, or about 6 million.
At 44,000 sq ft per floor in a WTC tower, this works out to about 136 thermite chip-projectiles per square foot.
