The 9/11 Forum

WTC1 perimeter behavior can be understood by dividing the perimeter into 3 distinct regions:

REGION 1 is > floor 97
REGION 2 is between floors 92 to 97
REGION 3 is < floor 92


The essay linked below records behavior of region 2 perimeter sections.

http://www.sharpprintinginc.com/911/index.php?module=pagemaster&PAGE_user_op=view_page&PAGE_id=61&MMN_position=146:146


I have been able to piece together most of region 2 months ago from large falling perimeter sections. There was one large section of the N face I was unable to fit.

2 days ago P1 sent me a pm containing a video clip which clearly shows the very perimeter section I have predicted must exist. It is huge and fits right into the N face section I was unable to account for.


Imagine my surprise when I saw the "missing piece", the piece I postulated must exist, emerge from the dust (behind WTC7).



There is a clear "phase transition" in perimeter behavior below floor 92. This is where serious perimeter resistance and "peeling" begin.


Edit 3-21-09: Some of the positions of these pieces are corrected later in this thread. There is good reason to conclude that at least some of the large perimeter pieces leading the falling objects are from above floor 97.

Fascinating. Great work.

from article wrote:Region 2, from floors 92 to 97, is discussed in this section. They are the earliest objects to become detached from WTC1, lead the fall on all visible sides of WTC1 and are unique in that...

1) They are all about 5 stories tall

2) They show no evidence of buckling or noticable deformations

3) Each one leads all other local falling objects in their descent.

4) They all trail a thick dust which obscures the collapse from view

There is also your observation that some failure occurred across straight lines, instead of along a staggered path. Region 2 was definitely special.

Is that video available for general consumption? I'm looking for clarity first, and unusual views second, any help appreciated. No problem if it isn't available since that starves my neurosis - either way works out great.

It is a 250 MB upload

http://www.megaupload.com/?d=DANBT6B5

The first 30 seconds are not of a new clip, but I've never seen that giant perimeter piece from the north face emerge before in other clips.

It is huge and yet it is rare to catch a glimpse of it. (because it reveals itself behind WTC 7)

The upload is well worth it. Achimspok is a cleaver guy.




The colors show the 3 regions. The lines in region 2 (pink) show roughly how the perimeter sections were separated in the earliest moments of the fall.

Region 2 perimeter sections showed very little resistance to separating from the building as opposed to region 3 (yellow) perimeter sections.


More to come..

Good find.

But, given that a pixel is about a quarter meter on a side, calling the crushed materials following the perimeter walls sections 'dust' is a inference and may be misleading.

Also, there is no reason to state that below floor 92 offered any more resistance than 92--97. It is just that by the time the upper portion (zone C) reached there, all was obscured.

Also, there is no reason to state that below floor 92 offered any more resistance than 92--97. It is just that by the time the upper portion (zone C) reached there, all was obscured.

Zone 2 and 3 perimeter sections show 2 entirely different behaviors.

They follow different trajectories.



Region 2 is yellow. Perimeter sections from there follow the path of the orange arrow.

They lead all objects in the fall. They land fairly close to the outside base of the building. They are the first objects to hit the ground.



Region three perimeter sections consist of long sheets that peel outwards in the direction of the pink arrow. One such sheet is represented by the pink graphics at three different moments of falling. They are not in freefall. They are still attached to the building at the base of the sheet.

Region 3 sheets resist destruction with remarkable tenacity. They do not break apart easily and are capable of pushing the top of the sheet hundreds of feet away from the base of the building before giving at their base.

2 of the most extreme examples of intact perimeter sheets are shown at the links below.


WTC1 W face megasheet
http://www.sharpprintinginc.com/911/index.php?module=pagemaster&PAGE_user_op=view_page&PAGE_id=62&MMN_position=149:149


WTC2 E face (it's a big one)
http://www.sharpprintinginc.com/911/index.php?module=pagemaster&PAGE_user_op=view_page&PAGE_id=63&MMN_position=148:148


Region 2 perimeter columns are covered in the OP.

Interesting fact:

Because we can see the region 2 column sections falling, we know where to look for them in the rubble should we wish to find them in photographs of the debris.


A few questions if anyone can help:

1) Can anyone guess how the perimeter columns in the linked photo received this kind of damage?
http://www.sharpprintinginc.com/911_old/Photo_archives/perimeter_anomalies/WTC0335_g1_z1.jpg


What about this spandrel in the left foreground?
http://www.sharpprintinginc.com/911_old/Photo_archives/north_tower_debris/4166.jpg


2) Can anyone place the viewing angle of this photo? From what face is this debris probably falling?
http://www.sharpprintinginc.com/911_old/Photo_archives/north_tower_prep_and_demo/911_HighQualityPhotos3526.jpg

Edit: Links fixed.

Thanks.

[Elided by author.]

To understand the extent and range of perimeter peeling around the W, N and E sides of WTC1...



The orange lines show the range of the farthest perimeter column sections.

West side is up, east side is down. Please note the extent of the peeling towards the east and west. (Wow)

The base of WTC1 is highlighted.


This is taken from a 14MB satellite photo available through 911Research below
http://911research.wtc7.net/wtc/evidence/photos/gzaerial3.html


You can see the distribution of perimeter columns extending from different faces of the towers in the cropped photos below. All these images are higher resolution, so if you can zoom in on details you can see quite a lot.


WTC2 east face: Quite an interesting perimeter peel.
http://www.sharpprintinginc.com/911_perimeter/satellite_WTC2_Eside.jpg


WTC1 west face: Sheet peeling up to 600 ft out from the base. The central part was cleaned up, but you get the point, I'm sure.
http://www.sharpprintinginc.com/911_perimeter/satellite_WTC1_Wside.jpg

This is how the perimeter columns were laid out extending from the west face just after 9-11-01. The peel is obvious.
http://www.sharpprintinginc.com/911_old/Photo_archives/perimeter_columns/911_HighQualityPhotos1592.jpg


WTC1 north face: The large region 2 N face section is inside the giant hole in WTC6. How far out did the N face peel? That is the big mystery concerning damage to WTC7.
http://www.sharpprintinginc.com/911_perimeter/satellite_WTC1_Nside.jpg


WTC1 east face: Perimeter sections mixed with WTC2 N face. Holes in WTC 5 near bottom of photo caused by WTC1 east face peel, a good 600 ft away??
http://www.sharpprintinginc.com/911_perimeter/satellite_WTC1_Eside.jpg



Were we so inclined...


Where could we expect to find sections from just under region 2, sections from around floor 90?

They are some of the farthest displaced sections along the red line.

Where could we find the region 2 sections shown in the OP link?

From around the yellow areas. The yellow marks are where I expect one of the large sections to be. We know that because we can see them fall in photos and videos.

Major_Tom wrote:2) Can anyone place the viewing angle of this photo? From what face is this debris probably falling?
http://www.sharpprintinginc.com/911_old/Photo_archives/north_tower_prep_and_demo/911_HighQualityPhotos3526.jpg

Taken from the northeast. The large exterior wall sections are the same ones as indicating earlier as coming from the (generally) east side of WTC 1.

But then, I'm not the best photo-interpreter around.

Major_Tom wrote:1) Can anyone guess how the perimeter columns in the linked photo received this kind of damage?
http://www.sharpprintinginc.com/911_old/Photo_archives/perimeter_anomalies/WTC0335_g1_z1.jpg

I don't see anything remarkable. It appears that the right end of the column was cut during cleanup.

What about this spandrel in the left foreground?
http://www.sharpprintinginc.com/911_old/Photo_archives/north_tower_debris/4166.jpg

Wow! I'll surmise by being rubbed by passing crushed materials before the spandrel fell away.

The simple GIF by OWE is a great way present region 2 perimeter behavior.



N face on left. W on right.


Region 2 is easy to see because it is well marked by the blackened tatooed lines.

The topmost and bottommost horizontal blackened lines serve as the borders of region 2.


Collapse initiation is a complex process in which large interconnected perimeter sections, one of which actually wraps around a corner, pop out from the tower and go into freefall.

The NE corner in region 2 pops out as a large sheet. The sheet consists of the 6 columns you can see on the far left, the entire corner assembly (with attached aluminum cladding) and about 12(?) columns from the E face.


On the W (right) face a very large 5 story, 25+ column perimeter section quickly detaches from the building and goes into freefall. There is yet another large section falling just behind this section. It is hard to see because the first very large perimeter section is blocking the view for most all cameras.

From the N face there is yet another very large piece that descends at freefall as a giant "dust cloud". It emerges from the blanket of dust around 50 floors high.




Will discuss more shortly.

From my computer program, crushing front reached floor 92 about 150 ms before

Code: Select all

         2.2329  17.111  17.180  +0.069

time (seconds), displacement of antenna tower feature calculated and measured (meters), followed by the difference.

This assumes, of course, no tilt. With tilt the south side preceeds the north side by the amount determined by tilt, about 4 floors.

I study the detachment of the large NE corner assembly below.

http://www.sharpprintinginc.com/911/index.php?module=pagemaster&PAGE_user_op=view_page&PAGE_id=91&MMN_position=223:223


North face large perimeter sections falling from floors 92-98, also of the "pop-out" variety, recorded below

http://www.sharpprintinginc.com/911/index.php?module=pagemaster&PAGE_user_op=view_page&PAGE_id=92&MMN_position=224:224

Update: Seems that the entire W face perimeter, floors 97 (98?) to 92, popped away from the building in three large sections.

The clip below shows the fall of the large 5 floor rectangular perimeter sections leading all W face objects in the fall.

W is on the right.

http://www.youtube.com/watch?v=1iT7mmmc-YY&feature=channel_page


(Note on this video: I wonder if I am wrong when I say the bottom of the sheet is the 92nd floor spandrel row. Could it be the spandrel row between the 97th and 98th floors? I say this because if you look closely at the sheet you can see a dark burned section near it's lower mid section. When I look at the building just before the fall I don't see such a burn mark in the mid 92nd floor, but I do above the 97th floor (almost identical).

OWE: Could this be the perimeter wall from the upper block, floors 97 to 102 or so? Look closely at the fire "stain" on the falling W side piece in the videos. Do you see what I mean?

You can see this same burn stain on the W face falling piece in the photo linked below

http://www.sharpprintinginc.com/911_old/Photo_archives/north_tower_prep_and_demo/911_HighQualityPhotos305.jpg

This can be compared to a W face photo taken at 10:18 linked below

http://www.sharpprintinginc.com/911_old/Photo_archives/fire_mapping_wtc1_west/10_18_8_92.JPG



Back to the video: The large 25+ story section you can see hides at least 2 other large sections. You can see pieces of what is behind the first perimeter sheet if you look carefully. The entire group of 98 to 92 floor perimeter sections fall together and rotate outward together.

They are released from the building at about the same time because they fall together and at the same rate.

Can you see how the bottom of this large piece appears as if it could be severed along the bottom of a row of spandrels?

By playing the clip at various speeds forwards and backwards you can see from which region of the building it originated from. I'll try to find a method to show this to the viewer.


The earliest photo in which a portion of a large W face perimeter section is discernible is shown below



In the cloud on the right side you can see the bottom of a large sheet emerge. You can also see some hints of the sheet in the dust.

The bottom of this section is even with about floor 80 in this photo (you can tell by the "reference squib", a light colored ejection on the N (left) face in the center of the building marking fl 78). I claim the bottom of the sheet is floor 92 (but I wonder if it is the 97, 98 floor spandrel plate).

In only a 12 floor fall, please notice how far it is from the building and how it is leaning outward.

Why would a large, 5 story, 25+ column perimeter sheet from floors 92 to 98 break off and fall away from the building unbent at such an early stage of collapse?

Major_Tom --- If you can determine how long after collapse initiation this breakaway occurred, I could then run my program to estimate the excess power available around that time. It will be quite large.

Which in one fundamental sense answers your question.