Adjacent perimeter N and W walls fail within 0.5s interval
Since the roofline of the building is shaped as a square, by tracking 3 of the 4 corners tilting, hinging and collective column failure can be quantified and understood. Synchronized video from the north (Sauret) and from the NW (NBC NW view) allows us to estimate the tilt orientation and the horizontal failure propagation rate. The objects and points shown in the 2 views below are tracked and plotted to achieve this
Points tracked near the NE and NW corners in the Sauret video at 59.97 frames per second.:
Drop curves of the tracked points, courtesy of Achimspok:
large:
http://img522.imageshack.us/img522/3816/nedrop30.png
large:
http://img6.imageshack.us/img6/4128/nedrop3.png
The NE corner started to descent in frame 211. The velocity curve kinks down in 209 because of symmetrical averaging. The roof line reaches a tilt angle of about 0.25° in frame 235.
The faster east tilt of the antenna started in frame 185. Once again, if the core was pulled east by a perimeter collapse of the 98 SE corner we may expect between frame 185 and 211 twice the east angle of the antenna at the south face and both south corners. The fire at 104 SW corner should move 0.2 meters towards east but...
http://img442.imageshack.us/img442/6379/firex.png
...the x-component of the 104 fire shows no motion at all (eastward motion = downwards slope of the curve). May be the top tilted towards south at the very same time and nullified the x-component. If so then we should see at least a downwards motion of the fire between 185 and 210 but...
http://img15.imageshack.us/img15/1323/fireyr.png
...the y-component of the 104 fire apparently moved downwards after frame 210 and may be between 145 and 185. Between 185 and 210 all 19 curves show an upwards tendency (flame up due to core collapse?).
If the perimeter forced the core to tilt then it appears to be impossible that the perimeter stopped to tilt right when the core started to tilt and vice versa. Hence, there is no detectable perimeter driven cause for the east tilt of the antenna.
The velocities of the corners are included in the graph. As I mentioned earlier, probably the best way to locate a release point is to look at the positional and velocity data together. The release point is when there is a drastic change in the velocity slope. We can see that the release point for the NE corner is about frame 208 and for the NW corner it is about frame 222.
There is only about 14 frames between the NE and NW corner release points. That is less than 0.3 seconds.
(source video:
achimspok Sauret version: starts some seconds prior to the shaking camera.
File specs:
97.730.578 bytes
Audio: Dolby AC3 48000Hz 6ch 224Kbps [AC-3]
Video: MPEG2 Video 720x480 (16:9) 29.97fps 9608Kbps [Video]
duration: 02:04,124
Video fields unfolded into frames to get 7440 frames at 59.94fps. Only a segment is used. Frame 2005 of the unfolded version is the first frame "000".
Here is a link to the original file:
http://www.megaupload.com/?d=E6WOP2QS)
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Next,
the SW corner 104th floor fire and the NW corners are tracked and plotted using the NBC NW viewpoint, courtesy of femr:
Measurement of the large antenna, SW corner fire and NW corner washer drops from the NW NBC viewpoint
(notes: Black - Antenna
Red - Washer
Purple - SW Fire
59.94 fps - Resolution Doubled. 1 pixel on the graph is 0.5 pixels on the original video.)
NW NBC viewpoint original file:
http://www.megaupload.com/?d=VABQMPWG
Youtube clip of the same view, lower quality:
http://video.google.com/videoplay?docid=-68536067411074880&hl=en#
.................................
Conclusion
Using this drop data from the first time in 911 research we can see that the SW corner of the west perimeter wall was released within 0.5 seconds of the NW corner.
From the data we can roughly determine that when the 3 corners are compared........
The SW corner was released first
The NE corner was released about 0.2 seconds later
The NW corner was released about 0.3 seconds after that.
3 of the 4 corners of the building are released within a 0.5 second interval.
Created on 10/17/2010 02:19 AM by admin
Updated on 12/11/2010 01:06 AM by admin
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