The engines and between the wings is the most massive part of the plane, and I am not disputing some penetration of that section. But the wings are still fragile compared to the steel, and would have been ripped open, causing an explosion. The fuselage would have been crushed before the center of mass hit, causing deceleration and acting to plug any hole formed. The center of mass would have slowed on impact with the external columns, backed by the floors, and would not have slowed only once the plane was completely in the building and hitting the core columns.

NIST's pictures of the supposed impact, endorsed by Greg Jenkins, are not plausible.

http://ningens-blog.blogspot.com/2007/05/nist-on-wtc2-impact.html

NIST does not disclose its assumptions, but I predict they assumed penetration of the fuselage, modeled the wings as a rigid projectile, and did not account for dissipation of energy through global inertia of the building. I think they did whatever they had to do to get that plane into the building as shown in the fake video.

NIST's fairy tale is very similar to the car going through a truck without damage before hitting a wall, which is what Gordon Ross said Bazant was claiming with his collapse theory.

The fuselage is light and airy, and there is no way it enters the building as shown. You know that, so you posit an elaborate and risky garage-door-opening explosive to explain that, based on a little flash in a video of questionable authenticity.

No, Real Truther, I don't know my claims are nonsense. Call me stupid if you will, but stop accusing me of being disingenuous.

http://infowars.com.au/forum/viewtopic.php?t=296
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On the 11th day, of every month.
http://www.youtube.com/watch?v=_Q9nRs8cu5Y&eurl=http%3A%2F%2Ftruthaction...

You can't just take their conclusions as given without addressing their assumptions. All you do in your Letter is say that NIST's theory is correct and consistent with the video -- that begs the question.

To that extent, I can answer your center of mass argument now -- you are basically saying all the visible deceleration occurred in the building because NIST said so. Given their performance on the "collapse," I think it is reasonable for you to show why their conclusion on this matter should be taken at face value.

Wierzbicki said in his Internet article that the fuselage would likely be crushed against the external columns, which form a wall. The plane would have decelerated some as a result, and the impact should have been dispersed somewhat by the plug formed, in addition to the global inertia of the building surrounding the impact area.

I did not take his quote out of context. The absurdity of the video was his initial impression, because it is common sense. I made it clear that I think he has cobbled together a model that purports to explain the absurd.

Karim and Hoo Fatt, also with unrealistic assumptions, showed that the plane lost 46% of its kinetic energy in perforating the columns. They consulted with Wierzbicki on the article, and they specifically say he only considered the energy lost at the portion of a wing impacting one column. I recognize that his article seems to suggest that he added that figure up for all columns.

Look at the other diagrams posted by NIST -- one of them shows the fuselage directly impacting a floor.

http://ningens-blog.blogspot.com/2007/05/nist-on-wtc2-impact.html

Even if it did not hit head on, it would hit two floors off center. The columns are backed by floors that would disperse energy. How can you and NIST argue that the aluminum fuselage would perforate this wall? It's absurd. Karim and Hoo Fatt assumed it through on the baseless assumption that it is of higher mass than the external columns, I assume focusing only on the mass of the portion actually hit and not accounting for global inertia.

Wierzibicki also says that the Sander situation is not comparable, yet you continue to say it proves something. The plane in Sandia decelerated 100% outside the concrete wall.

Why would the fuel not disperse on impact, both around the point of impact and into the building? (I'm not denying that some perforation of the external wall would not occur.)

Read the article by Gordon Ross just posted at Journal of 9/11 Studies. Materials do matter. So does global inertia -- why is Wierzbicki assuming that none of the energy is dispersed through the columns, as in a projectile impact?

The NIST theory you are endorsing sounds a lot like his analogy of a car driving through a truck to hit a wall.

The videos show the wing tips going in. I'm not arguing that this is physical.

I will be collecting your comments and responding in more detail later, and will try to list arguments as you suggest.

My answers before were general, and I whipped it off. I will try to address your claims more specifically now.

1. Fuselage penetration

I showed that this amount of energy required to peirce the exterior columns is less than about 10% of the energy required to crush the fuselage in the same post. There is absolutely no mystery except to those who have not grasped the basic physics.

You have not shown that. You quoted Wierzbicki's findings. I agree that they seem to have added the totals for each column, but still think I am missing something because Hoo Fatt, in a paper reviewed by Wierzbicki, said that "They considered only one column and a portion of the wing that interacts with it." Regardless, Hoo Fatt much higher loss of kinetic energy.

What you are saying is not plausible. The front of the fuselage would be crushed against the much stronger steel columns. Moreover, your comparison with the amount of kinetic energy needed for the more massive fuel-laden wing to shear the column, whatever that might be, is a non-sequiter. Wierzbicki states the obvious -- it is likely the fuselage would be crushed. There is no reason for it to perforate the columns prior to be crushed and pushed in by the center of mass following it.

2. Cutting of fuselage

The fuselage had to be intact to be cut in the way shown. The diagram shows it passing through the columns intact and being cut, and the fuselage maintain its basic integrity, though cut and partially disintegrating, until it hits the core columns. My point stands, so please lay off the rhetoric about misrepresentation. Obliteration against the core rather than the external columns is not plausible.

3. My "misconception"

We all agree that the plane must decelerate. You just say it happened inside the building, based on NIST's claim. The Journal of 9/11 Studies published a paper saying that deceleration should match kinetic energy loss. Responding to Stephan Grossman, who cited Wierzbicki, Eric Salter stating that 18% (later changed to 12%) matched the kinetic energy loss found by Wierzbicki. Reynolds said that there was no deceleration.
I found the Hoo Fatt article showing much higher kinetic energy loss, and said that is not consistent with 18% energy loss (despite Salter's recent criticism, that gives him the benefit of the doubt).

Later I found that Steven Jones gave a Power Point presentation saying that there was deceleration in the Scott Myers video (citing Salter's analysis of another video, the Fairbanks video.) Jones said that this deceleration was consistent with the kinetic energy loss claimed by Werizbicki. I pointed out in a crtique of Salter and Jones that they should have acknowledged the Hoo Fatt article showing higher kinetic energy loss, and also should have acknowledged that NIST was saying 0% deceleration in the Scott Myers video.

Deceleration or lack thereof remains a valid argument -- all you have done is use NIST to claim that all the deceleration all took place in the building. And your focus on the tail is somewhat of the straw man Arabesque loves to talk about, because I was talking about deceleration in general. Salter claimed to find deceleration in the Fairbanks video at the point the wings hit the building.

I think your claim that the plane would hardly decelerate, despite the wings and engines smashing into the steel columns (box beams, not a 1/4 inch plate), backed by steel and concrete floors, is ridiculous. That's your center of mass, and when that happened, the fuselage behind it would have responded by deceleration and deformation, torsion, fragmentation, etc. Just like Sandia. It did not respond at all. That's absurd. All your center of mass argument tells me is that the tail is not going to respond as quickly as I might have thought.

Whether or not I misconceived the problem is not the issue. The issue is whether the video depicts an unphysical event. You cite the NIST argument without question in saying that the event is physical. Quit hiding behind your claim that I misconceived the problem. The question is whether NIST has shown the video is physical or fixed the data to match the video. I submit the latter, and that your claim of "consistency"
is nothing more than that.

The below statement is wrong on so many levels:

Furthermore, you and Reynolds were misreporting what the NIST report was alleging --- the plane did not decelerate. Clearly, NIST reports a 91% decrease in KE (70% decrease in velocity) once the tail end clears the exterior wall. You were wrong, and so was Reynolds.

Of course I was not saying the plane did not decelerate at all. Did you hear me claim it popped out the other side? (You heard me question whether the engine popped at 120 mph, but never answered).

I accurately stated that NIST said that the plane did not decelerate at all before entering the building, relying on the Scott Myers video that it used to measure the speed of the plane (which was then plugged back into the kinetic energy analysis).

This is implausible, and on Steven Jones' own terms, it is not consistent with even Wierzbicki's data.

I already responded on the wing tips - I never claimed NIST said they pierced the building. The videos show them doing that.

If dispersion was inadequate for an explosion, that does not change my argument that the tanks would burst on impact and there would massive heat from friction to ignite the fuel. I'll grant you that point for now.

I don't agree that the tail would not have decelerated when the wings and engine smashed into the wall. Are you claiming that the tail did not decelerate in the Sandia video when it reached the wall? Are you claiming that the material in that huge cloud of dust and debris in the Sandia video has not decelerated?

It's late, and I'll have to think about some of your points. In the meantime, please consider whether your demands to "substantiate" and "answer my questions" are meaningful. I am explaining my position the best I can, and think I have been responsive.

I'm first going to address what you and NIST said, because you are correct that I did not accurately report what NIST said.

NIST explicitly said that the tail did not decelerate, so you are correct that NIST did not say the plane did not decelerate, and I was wrong to say that you claimed the plane would hardly decelerate. I hesitate to say you are right, because I cannot check your calculations and don't fully understand the issue, but I agree that your letter addresses a discrete misconception on my part, because I was reading too much into NIST's statement that the tail did not decelerate. I agree that this is separate from whether the plane decelerated. I need to be more precise in stating what you said.

All this proves is that I was wrong on this point -- I am conceding this and thank you for pointing this out. I believe you stated earlier that this was the only purpose of your paper, and for that purpose, would agree that it is appropriate to take NIST's FEA analysis as given ("self-consistent.").

If you read my statement, it did show some understanding of what you were saying, when I said "the tail is not going to respond as quickly as I might have thought." Maybe not - regardless, I understand better now. Moreover, I was not talking about the tail, but about the fuselage directly behind the wing and engines.

(I say "wing" because my understanding is that the wing is all one piece - I view the engines and the portion of the wing between the engines, where most of the fuel is carried, as the most massive portion of the plane. I also do this to cure myself of a misconception I had early on - that there are two wings merely attached to the fuselage.)

You ask me "where is the center of mass as soon as the wings strike the exterior wall"?

My understanding is that the center of mass is still the same, but it sounds like the right answer is that it has shifted back a bit. Is that because the tail is getting closer to the wing area?

Anyway, I am considering the impact of the wing between the engines is the most significant event. As I stated, I am not claiming that the plane could not pierce the columns -- I expect some penetration when this mass hits the building.

What I am saying is that when the engine and wing impact the external columns, which are backed by the floors, there is an intense reaction to the impact that has to be transmitted back through the fuselage directly behind it. That is where I expect to see deceleration, deformation, torsion, or a reaction of some sort. There is no visible reaction. And of course, there is very little visible reaction when the engine and wing hit.

I'll address your other points in a separate comment, later today.

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Believe it or not, Ningen, I am not out to trap you or get you.

You are applying an extreme double standard. You want me to substantiate everything I say to the n-th degree, which is fair. I am doing my best to argue that the videos show something which appears to be reasonable, physically speaking. However, you susbstantiate almost nothing in buttressing your own belief that a plane can not behave the way it did in the videos.

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Wierzbicki created a model and published his results. If he thought it was garbage, then why would he publish it?

There are many examples of scientifically proven concepts which ‘defy common sense’ --- if you want, I can name a half dozen or so. If science was based on common sense, then the entire rigorous scientific method would not be necessary. However, common sense is extremely subjective, especially since some people do not seem to have any (this is not directed at you, and I am sure you can think of many examples). ‘Common Sense’ is a terrible way to approach a problem scientifically since you are inherently approaching a problem with preconceived notions.

I do believe, in my candid opinion, that your preconceived notions, guided by your ‘common sense’, are blinding you from objectively look at the facts and analyses. However, I seem to be failing at arguing the points lucidly.

Before tangentially pin-pointing some issues, let me address what you have previously written:

Now+explain+how+that+fuselage+enters+the+tower+virtually+intact+rather+than+being+crushed+like+a+beer+can+against+the+massive+steel+wall+backed+by+steel+and+concrete+floors.

I have shown this repeatedly with the MIT energy arguments.

.+The+physics+drew+the+cartoon,+and+are+hidden,+yet+you+endorse+this+cartoon.+I+take+this+to+mean+that+you+have+not+been+able+to+find+NIST's+assumptions.+By+any+academic+standard,+that+makes+the+cartoon+worthless.

The NIST results are supported by the results of others. In particular, the agreement with the MIT study is fairly good --- not from a precise damage point of view, but in analyzing the energetics involved in the problem. One thing that struck me in the NIST report is their comparison to other studies in their discussion section, and that the NIST report actually states that much less damage to the core region was found from their FEA than in all the other studies. This result is not what one would expect from dishonesty --- however, it certainly does not, in an of itself, render the report analytically correct.

I read this part of the report, but I do not remember all the assumptions they outline. I do remember the report as being quite clear in methodology and assumptions. What is missing from their analysis is a double check on their work using simple numbers and analysis. The MIT report is actually a great double check especially since their assumptions and numbers are easily checked. The two reports fit well together in this regard. This is precisely the reason I keep bringing up the two reports to substantiate my claims ---- the MIT study offers an easy analytical method to understand the collision energies, and the NIST FEA offers a nice analysis as to how the different elements of the plane interact with different parts of the building with nice pics ----

I'm+not+denying+some+penetration.+I'm+saying+how+can+there+be+no+evidence+of+impact+like+seen+in+the+Sandia+video?+It+is+mind-boggling+how+you+compare+these+two+completely+different+videos

The forward momentum carried the parts into the building. The pieces were dispersed within the building.Again, if you look at the MIT study, very little energy is lost in breaching the exterior walls, so very little loss of net forward momentum will result. Therefore, there is no palce for the pieces to go but into the building (they still had most of their forward momentum).

In Sandia, the plane parts all suffered complete cessation of forward momentum after impact.

Read+Wierzbicki+-+he+says+"Projectile+impact+velocities+may+exceed,+by+an+order+of+magnitude,+those+that+were+encountered+in+the+WTC+Towers+impact."+The+plane+is+closer+in+velocity+to+a+car+than+to+a+high-speed+bullet.

No, this is not correct. The plane is closer to a projectile when dealing with the exterior columns. That has been the focus of our discussion, the exterior columns. Since Wierzbicki states that the plane did not activate the global inertia of the exterior columns and only shearing need be considered, he is implicitly stating the plane acts more like a projectile when considering the exterior columns.

My+understanding+is+that+the+center+of+mass+is+still+the+same,+but+it+sounds+like+the+right+answer+is+that+it+has+shifted+back+a+bit.+Is+that+because+the+tail+is+getting+closer+to+the+wing+area?+

OK. Now that the other stuff is out of the way, I believe this last point is very important.

You have correctly answered the question but for the wrong reason. It is true that the center of mass would have shifted more toward the rear section of the plane at this point in time. It is NOT because the tail is any closer to the wing area. It is because the ‘front of the plane’ is closer to the wing section ---- the impact would slow the front section of the plane down a bit due to the impact.

Let me explain center of mass. Consider a pencil. Where is the CofM of a pencil? It is located at the point where you can balance it on your finger (horizontally). The center of mass is actually the point inside the pencil where you could hypothetically attach a ‘string’ and the pencil would balance perfectly no matter what position it was in (vertical, horizontal, in between, etc.). You can’t really do this, but that is the concept.

For the intact plane, the CofM is located between the engines in the approximate middle of the cross section of the fuselage. If you hypothetically crushed the front 10% of the plane, the ‘balance point’ would shift toward the rear of the plane, yes? The Center of Mass would shift toward the tail end.

If the front of the plane was obliterated, or partially obliterated, or crushed some, but all the pieces, on average, slowed down a little from traveling forward, then the center of mass of the plane would shift toward the rear a little. Since the CofM shifts toward the rear, ‘the plane’ decelerates even though the tail end does not.

Anyway,+I+am+considering+the+impact+of+the+wing+between+the+engines+is+the+most+significant+event.+As+I+stated,+I+am+not+claiming+that+the+plane+could+not+pierce+the+columns+--+I+expect+some+penetration+when+this+mass+hits+the+building.+What+I+am+saying+is+that+when+the+engine+and+wing+impact+the+external+columns,+which+are+backed+by+the+floors,+there+is+an+intense+reaction+to+the+impact+that+has+to+be+transmitted+back+through+the+fuselage+directly+behind+it.+That+is+where+I+expect+to+see+deceleration,+deformation,+torsion,+or+a+reaction+of+some+sort.+There+is+no+visible+reaction.+And+of+course,+there+is+very+little+visible+reaction+when+the+engine+and+wing+hit.+

Except the Sandia video shows just the opposite… The Sandia video is a perfect counter example. Even though the plane is obliterated against a concrete wall and the momentum of the impacted section of the plane is *completely* haulted, the tail does not decelerate at all! Also, the fighter jet is a much more stiff plane than a passenger airliner, so you might expect to see some deceleration of the fighter jet tail (more effective ‘transmission’ of the inertial effects from the front of the plane to the tail end) even though you might see none from a Boeing 767 --- however, even for the stiffer fuselage of a fighter jet you see no deceleration of the tail section. The comparison can be made directly, and there is no problem in so doing in showing that no deceleration of the boeing 767 exterior to the building is expected when impacting a *less* rigid object (1/4” plate steel columns as opposed to a solid concrete block).

Hoo Fatt and Karim grossly overestimate the energy required to sever the exterior columns:
1) they assume the box column thickness is .37”
2) they assume that the weight of the fuel is evenly distributed along the entire wing, and therefore the entire wing either pierces all columns or none of the columns are pierced
3) they assume that the initial velocity is 500MPH, when the base case scenario is 540 MPH, an 8% increase in KE.
4) They assume normal incidence of the plane at a 0 degree angle (plane wing is perpendicular to columns)
5) MIT assumed the exterior columns were the less strong case of A36 steel, where Fatt and Karim assume a 1006 grade steel (stronger and more rigid, more in line with the steel actually used in the exterior columns)

This column thickness is awfully thick. It seems much too thick from the other numbers I have read. It should be cross reference to see if it is realistic instead of trusting my memory. Any excess column thickness is a major problem if one is interested in calculating the energy lost via breaching the exterior columns. Notice that in their analysis, they don’t really care how accurately they estimate the exterior column thickness since the point of their paper is to model a thickness of the exterior columns which will completely impede the wings from breaching the exterior columns (they find a 20mm thickness will do the job --- that can be *very* large added expense for builders). They only needed a ‘ballpark’ number to start with. It should be noted that MIT used the same thickness, but this can skew the results with the NIST report, so care must be taken.

The same can be said of their initial velocity. For WTC2, the initial speed of the aircraft was about 540MPH which is considerably larger than 500 MPH (an 18% larger KE). This is considerable since their analysis uses incremental sums of plastic strain on the columns. The faster the columns are hit, the less the ‘dynamic flow stress’, in equation 5.

A big error comes from assumption 2. They show the entire wing is able to breach the exterior columns since they assume a homogeneous wing. We know that the fuel was only located between the engines, and the remainder of the wing was much lighter. This means that the exterior wing tips may not be able to breach the exterior walls while the wing in between the engines are going to have a higher mass and may be able to breach the exterior columns. From videos of the actual impact, this is obviously the case, so fewer columns would be breached.

A large error comes from assumption 4. The planes which impacted the towers hit at angles (38 degrees for WTC 2 and 25 degrees for WTC 1)--- that is, the wings were not perpendicular to the columns. What this means is that less columns will need to be deformed, drastically lowering the ‘plastic work’ which the plane needs to do on the columns. Fatt and Karim assume 40 vertical columns were breached which is about twice as much as was actually breached.

In the MIT study, they only assumed about 20 columns sheared (I recall the number 23, but I could be a little off). That means that the energy is automatically cut in half. 49% loss in KE then becomes a 25% loss in KE. This energy includes the deformation of the plane AND the work done on the columns. MIT calculated the two separately. The energy required to sever the columns was calculated to be 4%. The work done on the plane which they figured in separately is necessarily in the ballpark of 4%, so this gives 8%. So if we compare apples to apples, we have 8% work done on the plane and columns from MIT, and 25% work done on the plane and columns from Karim and Fatt.

The difference in the grade of steel will definitely skew the results. I doubt it will scale the entire 12% spread, but it will certainly bring the numbers closer together.

So there you have it: something significantly greater than 8% from MIT due to their assumption of A36 steel compared to 25% for Karim and Fatt.

BTW, Karim and Fatt show that the fuselage easily breaches the exterior columns as well as the wings. They explicity state that “the wing section is assumed to be a rigid projectile since the FEA showed that much deformation did not occur in it as it cut through the bracing column.” That is, the wings and fuselage easily cut through the exterior columns without suffering massive damage (within their assumptions), and when they compared the FAE analysis (where the wings can deform) to a purely analytical method where the wings can not deform, not much difference in the energy required to pierce the exterior columns resulted (something like a 20% difference).

Of course, the higher Fatt and Karim value also results from allowing the beam to bend causing inertial losses which MIT did not consider. But it is not all that much higher.

So, all 4 FAE analyses (Purdue, WAI, NIST, Fatt) all agree that a boeing 767 can easily peirce the exterior columns with at most 25% loss in KE in little deformation of the plane, and the MIT analytical energy balance equation shows that a boeing 767 can easily pierce the exterior columns without much deformation --- no problem.

5 independent studies, and 5 conclusions which clearly state that a boeing 767 can breach the exterior columns easily.

I hope that beer can is not still troubling you....

It argues the nose-wingroot ratios documented exclude 767-200s and goes on to point towards a 767-200 tanker as the likely culprit...
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interns < internets