The 9/11 Forum

Two out of three coordinates ain't bad,

Per viewpoint, not too shabby at all. That is a lot of information.

tfk's latest:

tfk wrote:You know what would be really cool?
If you were to list the underlying assumptions that accompany those equations.

The obvious ones that occur to me include:

1. you know accurately the location of the pivot point
2. the pivot point really is on the outer wall
3. the pivot point acts like a perfect hinge
..3a. the pivot point doesn't move during rotation
..3b. all motion is purely rotational
4. all rotation is perfectly in the plane of the sketch

In the collapse of any building, including the towers, I'd expect, a priori, none of them to be strictly true.

I agree with the last statement, but let's have a closer look at the points listed.

tfk-1. you know accurately the location of the pivot point

No, the location of the pivot point is not known. I'm not even sure there is a pivot point per se, so how can I claim to know where it is? The whole point of this exercise is to say what would happen if certain assumptions were true, then see if these things happened. If not, then it becomes unlikely or even impossible for the assumptions to be true. This is where the argument stands right now, at the cusp of refutation.

Items 1 and 2, as written, are not distinct. Both refer to uncertainty in location, so I will take item 1 to refer only to vertical location on the wall, since item 2 refers to horizontal location within the building.

How important is it to know the precise vertical location of the hinge in arguing the validity of the assumptions? It's not important at all. The hinge could be anywhere on the north face and the consequence of the NW corner appearing to go down remain true. The further up you go, the less apparent roofline motion would be next to antenna motion, the further down you go the opposite occurs. Therefore I presume tfk would suggest the hinge may be higher than we assume.

The work has been done assuming story 98 is the hinge location. You want to go higher, tfk? This is about as high as practical, sorry. The hinge is taken to be the topmost position observed to break at onset of global collapse. If you want it to be higher, then you'll need to account for the fact that it mysteriously broke somewhere below, where it was not hinging, and where the wall shows no significant distortion from any view. Moreover, the upper north wall is seen to descend at a break point much lower than 98 over most of the face. The north wall moves down as a unit, slowly at first, from points as low as the lowest region of the impact hole.

Thus it is seen the choice of story 98 is motivated by physical evidence and represents the highest placement practically and realistically possible. Of course, one can imagine the location to be higher, but there is no justification for asserting it must be so, and plenty of evidence that it could only be imaginary. The fact is, the average hinge location (if any) is likely to be running along a diagonal in which the highest point is at 98. I see no reason to consider ill-conceived imaginative ideas in this scenario.

The choice of story 98 as the highest possible location is already conservative and represents the best case for minimizing roofline motion while maximizing antenna motion. Item 1 is the type of suggestion that results from coming to the party late.

At any rate, you can move it all the way to the roofline if you want, but what do you have? The antenna going down while the roofline stays fixed... exactly what Major_Tom is claiming. Hahaha!

You certainly can expect to see a top section of a structure tilt when a large amount of the axial support of it is removed or compromised on one side. However, as one set of support columns are "unloaded" the remaining ones are seeing increased loads and likely subject to buckling failure and or pushed laterally by the tilting of the structure. For a hinge to "develop" support would have to be expressed in a line through the structure... likely at the columns which are seeing the increased loads. The columns on the ling of the hinge would see most if not all the loads of the structure it supports and which is rotating. It seems unlikely that so few columns could support the hinge without buckling or displacement and the motion therefore would not be the simple rotation described by an arc around a hinge. Intuitively the motion would be more complex and the block would be descending and moving laterally. No?

[Hang on, SanderO, I'm on a roll]

tfk-2. the pivot point really is on the outer wall

Again, this is coming late to the party. For years, this has been a standard model for discussing rotation of WTC1, and it is taken to be true by most researchers who do NOT believe in CD. In fact, interior hinging is not considered for WTC1 precisely because there is no detectable upward motion of the north face, as there is with the west face of WTC2 (the hinge point has been determined by observation there to be interior). No less than Greening and Benson, both published in JEM on this very subject, place the hinge on the wall.

In the absence of other information, I will take the opinions of published authors and observations culled over years of study (including by me) versus an offhand remark by a proven incompetent who is only grasping at straws to derail an argument.

All the same, what if the hinge is interior? tfk says in a subsequent post:

tfk wrote:When I used the diagram that MT had posted (assuming that the dimensions & perspective angles were approximately correct), then the location of the pivot point at which the corner would move along the sight line (& have little apparent motion) was about 55' inward from the outer wall.

FIFTY-FIVE FEET! Good thing, too, because at least you have something substantial there on which to pivot - the core columns. Otherwise, what would the entire upper block be pivoting on if the location were between core and north wall? Between four and eight perimeter columns resisting bending moment. Hahaha! Good one!

Here is another funny thing: tfk acts like no observation whatsoever has been done from angles other than Sauret, let alone measurements. This is false, as anyone not late to the party knows. While it is not possible to achieve the Sauret resolution with other videos, there are many views with sufficient clarity to determine gross motion and to easily detect buckling or out-of-plane deformations. The west face has been observed and checked for indication of buckling of the sort readily observed on the north face of WTC2.

Nothing of the sort has been seen. What does this do to the notion of an interior hinge? It makes it well-nigh impossible. There is no way the upper block can tilt as a unit on an interior hinge and maintain parallel perimeter columns. I wonder if tfk has seen the incredible series of buckles moving across the north face of WTC2? Can't miss 'em, even in the shittiest of videos. That's what happens when a perimeter wall is deformed in its own plane about a center of rotation.

But that's not all. What happens to the lowest perimeter edge of the upper north face on WTC1, around story 92, while all this is going on? If there is an interior hinge anywhere at or above story 92, this segment would have to move up. Instead, it is seen with fairly good precision to remain steady until slowly creeping downward. There is NO upward movement.

Wrong. Next.

PS. the deformation-as-opposed-to-tilt scenario still requires primary load bearing members to resist catastrophic collapse until it actually happens. Good candidate would be the outer core tfk points to. tfk, if you slither much farther, you'll be making the same argument I am.

SanderO wrote:It seems unlikely that so few columns could support the hinge without buckling or displacement and the motion therefore would not be the simple rotation described by an arc around a hinge. Intuitively the motion would be more complex and the block would be descending and moving laterally. No?

I agree. I favor slump with deformation over tilt, simply because the north face had the least perimeter of all yet doesn't show any substantial deformation at the NW corner until global collapse, as far as I can tell. The hinge is an academic argument as far as I'm concerned; nevertheless, there are quite a few people who believe in a literal hinge.

tfk-3. the pivot point acts like a perfect hinge
Who said this had to be so to preserve the nature of the argument?

tfk-3a. the pivot point doesn't move during rotation
That's deformation, not tilt, as was to be shown. Can you imagine a "hinge" rolling up or down the north face and NOT calling it deformation? Likewise a point of moving rotation inward or outward, that's deformation, not tilt.

tfk-3b. all motion is purely rotational
That which is not pure rotational and translational motion of a rigid body is deformation, as was to be shown. tfk, are you clear on which side you argue?

tfk-4. all rotation is perfectly in the plane of the sketch
First of all, I'll say the same thing I said above. Who said this had to be so to preserve the nature of the argument? The sketches are offered as 2D simplifications. We already know the motion is not exactly in the plane of the sketch and there's change in rotational direction of the antenna as it descends. So what? We also know the rotation is in the general direction away from the camera and can see little side to side displacement in the Sauret video, thus know the early tilt is practically speaking nearly contained in a planar region. The approximation is therefore valid by way of direct observation.

Nevertheless, the geometric argument still holds for any direction away from the viewer. There's no plane of rotation in which the roofline point will appear to remain stationary as the antenna moves appreciably - IF it is moving as a rigid block.


Nice try. Not.

tfk finally gets something right.

tfk wrote:One non-observed consequence of this would be that, if the upper block truly acted as a rigid body, then a visible, horizontal external crack should have opened up on the exterior north face of the building during this rotation.

Correct. Not observed. Next.

tfk wrote:However, it is entirely possible that the core columns were the actual pivot axis, and the block rotated generally around this line, and the building deformed enough in the lower right quadrant of the upper block to not produce that crack.

Hahahahaha... OK, if you say so.

The hoops some people will jump through to try to avoid admitting deformation of the upper block; why, they'll even resort to deformation as the explanation for why deformation can't occur. Ahahhhhahaha!!!!

Next.

tfk wrote:The funny part is that, if MT would simply do the proper "multiple perspective" vector analysis, he'd have the correct answer to all of this speculation.

Actually, I thought the prior comment you made was a great deal funnier. Here again, tfk pretends other viewpoints haven't been examined or measured, where in fact they have. I haven't done it myself, so naturally I consider acceptance provisional. Hell, I consider all this provisional; I just hate bad arguments.

Ironic that he has repeatedly refused to do the one calculation that would answer all these questions, ain't it?

As I've said now a dozen different times and ways, multiple angles have been examined yet multiple angles are not needed to demonstrate motion inconsistent with rigid body tilt. Since tfk's arguments now consist of defending the rigid body hypothesis by claiming it wasn't rigid, I'd gather he's come to the same conclusion but doesn't even know it.

Dare I make one more prediction? Before too much time passes, tfk will be casually dropping lines in other threads about how the upper block has been shown to deform at initiation - by him! (take note alienentity, I might want to collect that Rasputin's million someday, could use you as a witness)

Major_Tom wrote:

Two out of three coordinates ain't bad,

Per viewpoint, not too shabby at all. That is a lot of information.

tfk argues from the perspective of a blind and from this perspective he is "right"
BUT
we know not just some video that was taken somewhere. We know the point of view. We know the real world size. We know the expectable from other views. We know the principles of perspective and geometry.
Hence, we can measure 2 coordinates out of 3 directly in the plane rectangular to the line of sight. We have the 3rd dimension of time and therefore motion in the sense of "change of the appearance" over time. The known POV + perspective + real world size allows to calculate ALL freakn data one could wish. What's tfk's problem? That we cannot see a red line for the hinge?

He just talks out his ass. Endlessly.

W. D. Clinger asks "Can anyone rule out a rotation-induced 18-inch horizontal sway...?"

I think this does it.