Final close-out
Just a few more replies, cleaning up some issues that
Miragememories raised, in case there's anyone else who had similar questions.
This is how I addressed your point about "the wide range of selection criteria";
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Not substantiated by video or photographic record. Requires extrapolation based on "little hard data".
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Not substantiated by video or photographic record. Requires extrapolation based on "little hard data".
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Partially substantiated by video or photographic record. Requires some extrapolation based on "little hard data".
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Not substantiated by video or photographic record. Requires extrapolation based on "little hard data".
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Partially substantiated by video or photographic record. Requires some extrapolation based on "little hard data".
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Partially substantiated by video or photographic record. Requires some extrapolation based on "little hard data".
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Requires extrapolation based on "little hard data".
Yes, you addressed it as a series of giant hand-waves. Not very useful. Admittedly there is some information that has to be experimentally estimated, which is why NIST ran such a huge model in the first place instead of simply issuing a report of findings -- in the Pentagon case, since the structure survived intact enough to reconstruct what happened, no model was necessary, though some were run anyway out of scientific interest. But for anyone to discount the additional evidence simply because it's only "partially substantiated" is disingenuous.
We don't know exactly where office furniture landed, but we know roughly how much there was at start and watched the fire progression. We have hundreds of hours of video from all angles, and we know the sequence of windows broken by fire. We have pictures showing some damage to the interior, such as sagging floors and progressively bowing perimeter columns. We know
exactly how long it took the towers to actually start collapsing after being hit, by the way, something you claimed "required extrapolation."
In other words, there is a pile of evidence. NIST explains this. This is why we aren't laser-focused on what happened to two individual chunks of debris. In the larger scheme, they just don't make that much difference.
If the simulation had been running on the less core damage scenario as it should, the towers would have either taken longer to reach collapse initiation, or they would have not reached collapse initiation at all. In either case, we would end up with results that would not agree with what was observed!
There's a lot of "if" coming from this statement. It should be clear to everyone that NIST would not bother to run a fire simulation on a damaged building model that, in their own opinion, was observably less accurate than a different case. That's why they didn't even bother with the "less severe" case. It was clearly a poor fit, as I've proven above.
In light of the fact that only the most extreme case scenario reached a threshold that resulted in a simulated collapse initiation, the importance of additional simulated core damage that should not have existed in any of the case scenarios, is particularly significant.
It seems to me that you're complaining because their simulation, using their best choices, matched what happened in real life pretty well. "Only" the most extreme impact scenario was even tested, because it was the best fit, as we've proved. So naturally, "only" the most extreme impact scenario would give us a reasonable answer.
Would you have been happier if their simulation didn't match? I doubt it. Your reasoning is circular.
The comparison shows that an expanded fuel cloud did not produce sufficient loading to fail a core column with the exception of points close to the wing root at the highest impact speeds considered. A more realistic fuel cloud dispersion would have included lateral and longitudinal spreading, as well as removal of some fuel from the cloud as a result of impact with the outer wall and building contents. Under these conditions, it is expected that the fuel cloud alone would not be sufficient to fail core columns.
pg.376-77 NIST NCSTAR 1-2B, WTC Investigation
Hmm...sounds like NIST disagrees with you.
This was a bait-and-switch. Poor showing on your part.
Before, you had
claimed that
"[you] disagree that the jet fuel, even at 570 mph, as in the extreme case scenario, had enough concentratible momentum to cut the towers steel perimeter columns." What I showed you, using Figure 10-5 of NIST NCSTAR1-2B, is that the fuel had enough momentum to sever the stronger core columns, all by itself,
if not diffused. And at the perimeter, the fuel would not be diffused.
This diffusion occurs due to impact and the distance between the perimeter and the core. The NIST report is correct in stating that,
by itself, the fuel would not have failed any core columns, because it would have spread to roughly the height of a single floor before reaching them. (The fuel
in concert with bits of airplane, however, do have enough P-I to fail some core columns.)
But that's not what you said. You were talking about the perimeter. At that point, the fuel is not diffused, and thus the pink triangle values on the P-I chart apply. Therefore, the fuel
all by itself does indeed have the momentum to fail perimeter columns, you are wrong, and your attempt to mislead by baiting-and-switching back to the core is depressingly dishonest.
Fire damage was critically dependent on the amount of impact damage, otherwise no collapse initiation. Therefore, since only the extreme case simulation of impact damage resulted in a successful fire damage collapse, any unwarranted impact damage was very significant.
Once again, the extreme case was the best fit to reality, even before the fire modeling, so naturally we expect its results after fire modeling to best approximate reality.
Because the model mishandled these "non-inconsequential" aircraft components, the impact damage was simulated to be greater than it was, which improved the success potential for the fire damage.
Backwards. As proven above, the exit of these components indicates more damage to the core, not less.
The core was much more vulnerable to the effects of the concentrated energy transfer of heavy titanium steel aircraft engines and landing gear than it was to that of the softer debris field represented by fuel, plastics, glass, aluminum etc. Granted that debris field had a large amount of kinetic energy, but it was more easily absorbed as it was dispersed against the heavy steel core columns.
Ridiculous.
How is this energy "more easily absorbed?"
When speaking of distributed loads, NIST invokes a P-I chart, as quoted before in Figure 10-5 of NIST NCSTAR1-2B. The P-I chart represents the
pressure and the
impulse of impact, which are not truly unrelated items. Pressure sums to
force, and impulse is force times contact time.
For a solid, hard object, say titanium, the
force is no greater than if it was a chunk of clay. But the
impulse may actually decrease, because the titanium block is more likely to richochet off to the side. Not necessarily -- this is highly dependent on geometry of each specific impact -- but it is quite possible for a harder, stronger object to do less damage.
About "more easily absorbed," how? All of these objects, large, small, hard, soft, etc. are all hitting at the same time. This sums up to one
huge impact. Where exactly is this absorption supposed to happen?
Answer, it doesn't.
The other observable evidence that NIST "evaluated against the less severe and baseline scenarios, and found to not be the best fit", was the fact that they would not lead to the observed collapse of the towers.
This is a lie.
The NIST report does not use eventual collapse to evaluate the initial impact cases against each other. However, they do use the opposite -- any impact that results in the
immediate collapse of the tower is discarded as being too severe. I expect you confused these two ideas.
Dr. Greening may be right about the aircraft arriving with sufficient total energy potential to completely destroy an entire floor of core columns BUT, and this is a point your argument seems to consistently ignore, the energy would require the guidance of artificial intelligence AI, to sufficiently parcel and focus itself against all the heavy steel core columns. So while Dr. Greening's math my work in theory, in practice it defies the laws of probability.
"The laws of probability?"
We all know most of the energy wasn't expended on the core columns. Some went clean through, some was expended smashing furniture and drywall, some crunched up the plane, etc. Greening's
paper discusses this in detail. Go read it.
The point I was making is that the pitch angle of the aircraft was the dominant factor in impact damage, not hardness of materials, velocity, or anything else. Had either WTC tower been hit by a plane travelling flat and level, I would expect the tower to have collapsed instantly.
Focusing the entire impacting energy of the aircraft into a single point, would blow a hole through the tower based on the diameter of the concentrated energy necessary to overcome the obstacles in it's path. The hole's diameter would steadily shrink due to energy loss while advancing through the major building structural steel components.
Not at all. The hole would expand, as impact ablated and added random lateral velocity to the impactor, and as secondary pieces were swept along. I assume you've never handled a firearm? Bullets through ballistic gel show this effect quite nicely.
I have no support for your argument; "The majority of impact damage in the core was due to "diffused energy," essentially a pressure load on the columns themselves." I believe we already covered this earlier, but if you have better information than Chapter 10 which I discussed, I'd like to hear it?
You have plenty of support. The NIST model describes the damage as predicted by their models. The Pentagon BPR, which shows actual pieces hit by a similar plane travelling at similar speeds, finds evidence of distributed loads and only distributed loads. This is what we expect from experiment and observation. Hard to get more support than that.
Well we disagree about how the core was damaged and how much the core was damaged. I attribute the damage primarily to the result of stopping heavy, materially strong objects like the 3 titanium steel engines and 3 sets of landing gear.
You have no basis for this belief.
It is not my belief that the core was ever sufficiently compromised to allow the post impact fires to deliver the death blow.
You have no basis for this either. Belief has no place in this discussion. It is because of this unsupported belief that you reject the entire NIST conclusions, even though you lack the background to grasp it fully.
The NIST simulation made it so but it took extreme case parameters and the addition of an engine and 2 or 3 sets of landing gear to reach the collapse initiation thresholds.
As explained above, even had we subtracted those components from the model, the eventual collapse results would have been the same. Pitch angle is the key, not mass, not strength, not velocity, not weight. The NIST report shows this.
Fill a bag with water and swing it against people and other objects and the momentum created is quite powerful and damaging. Once that bag ruptures, it's a completely different story.
Here we have another example of "common sense" being completely wrong, and this is why we can't use it in an argument.
It all depends on speed. At the speeds you can swing a bag of water, sure, you're not talking about enough momentum to fracture bones or walls. But accelerate to higher speeds, and momentum dominates any ordinary container's material strength. Waterjets are commonly used to cut steel. No container required.
And finally, we come to the
coup de grace:
I realize this is far from a full parameter illustration but the point I feel is valid;
A REAL Scenario;
1) We take a simple cardboard box that is precut so that it is supported internally by a mass of evenly spaced wood columns.
NOTE: We'll label it WTC 1 (to avoid the issue of the simulated debris exit in the NIST extreme case for WTC 2).
2) We throw piece of wood with 5 loosely-held heavy metal fasteners at the box.
3) We observe the piece of wood is completely absorbed by the box.
4) We observe 2 of the metal fasteners break out the other side of the box.
5) We observe the box remain standing.
6) Done.
The MODEL Scenario;
1) We create a computer Model of the same box.
2) We throw a simulated board with 5 metal fasteners attached at the model at 3 different speeds.
3) When the simulation is run, we observe for all 3 speeds low, medium and high.
4) The board is absorbed inside the box for all 3 speeds.
5) None of the fasteners break out the other side of the box for any of the 3 speeds.
6) For the fastest throwing speed, we observe the box collapse.
7) We remove 2 of the fasteners, reset the Model and repeat the simulation with the 3 speeds.
8) The box remains standing for all 3 speeds.
This was really quite breathtaking. Here you are, expending thousands and thousands of words complaining about the "inaccurate" NIST model, and then you turn around and propose a
cardboard box with someone throwing a piece of lumber through it.
The phenomenology of lumber vs. box is so radically unlike the WTC cases as makes any comparison impossible.
Despite this, it still proves my original point. The harder you throw your stick, the more likely the "fasteners" are to come out the other side. Exit of debris, particularly debris that we
know had to have come in contact with the core, indicates a more severe impact.
I've remarked before that the NIST WTC models, all of them, are remarkably complex and would have been impossible, unthinkable, only a decade ago. They're not perfect. Still, they give us some usable conclusions, and for those unfamiliar with modeling, the NIST report describes how real scientists use these tools in detail.
Even if the NIST models gave us totally unrealistic conclusions, our reaction would not be to suspect "foul play" at the WTC. Model errors would not automatically mean that stealth explosives or invisible beams from space levelled the buildings. Instead, it would lead us to question our own methods more thoroughly, and if no fault could be found, to then suspect an additional but mundane factor in the collapses -- substandard building materials or practices, or unexpected fire effects such as underappreciated chemical activity proposed by Dr. Greening, that sort of thing. A proper criticism of the NIST report evaluates its methods objectively, asking whether or not its conclusions are accurate enough to issue recommendations. And the answer is, in my opinion, while there may still be some unknown factors like those above, those factors were certainly not
required for the Towers to collapse, and thus alternative hypotheses must be viewed as supplementary at best, to be discarded unless there is definite evidence of their presence.
This is not the position Steven Jones
et. al. have taken. Their entire approach is to highlight any perceived ambiguity in the report, whether or not it exists, for the sole purpose of keeping their own theories alive. Theories that have no evidentiary basis whatsoever. Much as
Miragememories slanders the NIST model while proposing his cardboard box, Jones and his cronies mock the NIST hypothesis while promoting a fantastic, incomplete, and self-contradictory spew of half-baked ideas. This hypocrisy serves no one except the individuals making a profit from it.
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That should conclude this examination of the NIST impact models and the Jones petition. Thank you all for your indulgence.
