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B&L Revisited - Rigidity and Crush Direction(s)

Analysis of airplane impacts, fires and collapse theories and examination of related evidence.

Re: B&L Revisited - Rigidity and Crush Direction(s)

Postby OneWhiteEye on Wed Nov 04, 2009 9:19 pm

femr2 wrote:Initial data for linear ejecta traversal from West face of WTC 1:

That's the bomb! So to speak, of course, in the terms of delinquent youth of a few years back. Thank you.

femr2 wrote:I'd quite like to see discussion of the linear ejecta trace I posted earlier TBH.

Know that was directed at David B. Benson, but I'm very happy to discuss it. It is worthy of its own thread, but let it at least start here for its relevance to the topic.

First, it's not precisely linear, though that is a reasonable approximation after about 2 seconds. Taking the running averages and the fit, the speed increases to a plateau then begins to decrease. This is most interesting. If the peak is less than or equal to terminal velocity as calculated by David B. Benson for the standard model, then it is somewhat less interesting but still would leave much to explain.

Major_Tom has been stressing different parameters for different sections. Now, some of it is being quantified, an essential step away from impressions and into metrics. I hate to say (since I'm one to talk), but meters will be needed to answer the big question: what is the peak velocity? Is the frame posted above the same scale?

Your vid was fabulous.
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Re: B&L Revisited - Rigidity and Crush Direction(s)

Postby David B. Benson on Wed Nov 04, 2009 9:34 pm

femr2 wrote:So N & W outside. S & E inside. Is that your view ?
Yes, temporarily.

What is the relevance to crush down/up ?
Possibly that niether applied to those upper truss seats.

Whereas crush down would ?
I doubt it.

Are you saying that the mass quantity has no effect ?
I have only tried no mass ejection and 20% mass ejection from zone B. This has essentially no effect on agreeing with OneWhiteEye's measurements except to change the parameters slightly.
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Re: B&L Revisited - Rigidity and Crush Direction(s)

Postby femr2 on Wed Nov 04, 2009 9:58 pm

OneWhiteEye wrote:First, it's not precisely linear, though that is a reasonable approximation after about 2 seconds. Taking the running averages and the fit, the speed increases to a plateau then begins to decrease. This is most interesting. If the peak is less than or equal to terminal velocity as calculated by David B. Benson for the standard model, then it is somewhat less interesting but still would leave much to explain.

Agreed, though I'm intending upon correlating the data with the BBC footage to increase accuracy.
http://www.youtube.com/watch?v=zb1PfiBT7A0
The quality of the source footage used is not great, and it's very possible that the curve will change somewhat when made more accurate, though the trend should remain.)

Major_Tom has been stressing different parameters for different sections. Now, some of it is being quantified, and essential step away from impressions and into metrics. I hate to say (since I'm one to talk), but meters will be needed to answer the big question: what is the peak velocity? Is the frame posted above the same scale?

No, the source is bigger. Shrunk to fit the forum.

All my images have preview...
http://femr2.ucoz.com/photo/linear_2/6-0-217
Linked to:
http://femr2.ucoz.com/photo/6-0-217-3 (1280x720px/74.6Kb)

I'll get the actual data source video up and post a link.
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Re: B&L Revisited - Rigidity and Crush Direction(s)

Postby OneWhiteEye on Wed Nov 04, 2009 10:36 pm

Roughly, I get about 25 m/s at about 5 seconds in. However, most of that speed is achieved by the 3 second mark, so if it ends up being more nearly constant, the time interval to reach peak ~ terminal speed is maybe closer to 3 than 5 seconds.

It may be more appropriate to think of the rest of the internal progression being slow, rather than this part being fast. Roofline fast, inside slow, except for the part with the most mass on it and where the upper may have slipped inside. Hmmm.....

Double-checking encouraged.
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Re: B&L Revisited - Rigidity and Crush Direction(s)

Postby femr2 on Wed Nov 04, 2009 10:42 pm

OneWhiteEye wrote:Roughly, I get about 25 m/s at about 5 seconds in. However, most of that speed is achieved by the 3 second mark, so if it ends up being more nearly constant, the time interval to reach peak ~ terminal speed is maybe closer to 3 than 5 seconds.

It may be more appropriate to think of the rest of the internal progression being slow, rather than this part being fast. Roofline fast, inside slow, except for the part with the most mass on it and where the upper may have slipped inside. Hmmm.....

Double-checking encouraged.

Source video...
http://femr2.ucoz.com/ffdemhd_264.avi

I'll check for aspect ratio, and scale to vertical features rather than the horizontal scaling I've used, but 25m/s seems a reasonable mark (I get 27 with very dodgy measurements :) )

What was DBB's terminal velocity figure ?
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Re: B&L Revisited - Rigidity and Crush Direction(s)

Postby David B. Benson on Wed Nov 04, 2009 11:01 pm

femr2 wrote:What was DBB's terminal velocity figure ?
About 28.8 m/s for the advance of the crushing front (material speed is necessarily less) but already at 3.76+ seconds the crushing front is advancing at 28.5 m/s.
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Re: B&L Revisited - Rigidity and Crush Direction(s)

Postby OneWhiteEye on Wed Nov 04, 2009 11:06 pm

Interesting. With my approximations, the 25 m/s figure is likely a bit low.
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Re: B&L Revisited - Rigidity and Crush Direction(s)

Postby David B. Benson on Wed Nov 04, 2009 11:13 pm

OneWhiteEye wrote:With my approximations, the 25 m/s figure is likely a bit low.

If crushing front speed, not much. At 3.0 seconds the crushing front was advancing at 26.35 m/s by the calculation I'm currently looking at (and reporting).

Edited to add: I'm a bit puzzeled but if you two have a way to estimate crushing front speed with some accuracy that should be taken as more definitive than the model calculations.
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Re: B&L Revisited - Rigidity and Crush Direction(s)

Postby femr2 on Wed Nov 04, 2009 11:42 pm

Thought it prudent to split the discussion out to:

Linear/Terminal Velocity Thread

I'll still post any thoughts on implications for Rigidity and Crush Direction(s) here of course.
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Re: B&L Revisited - Rigidity and Crush Direction(s)

Postby OneWhiteEye on Wed Nov 04, 2009 11:53 pm

David B. Benson wrote:Edited to add: I'm a bit puzzeled but if you two have a way to estimate crushing front speed with some accuracy that should be taken as more definitive than the model calculations.

Yes it looks like it has been measured roughly, a first as far as I know. Interesting to note that the model is quite close, even more interesting since the propagation is not uniform laterally and this is the very fastest part we're talking about, of what can be seen.
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Re: B&L Revisited - Rigidity and Crush Direction(s)

Postby femr2 on Sat Nov 07, 2009 2:33 pm

OneWhiteEye wrote:
David B. Benson wrote:Edited to add: I'm a bit puzzeled but if you two have a way to estimate crushing front speed with some accuracy that should be taken as more definitive than the model calculations.

Yes it looks like it has been measured roughly, a first as far as I know. Interesting to note that the model is quite close, even more interesting since the propagation is not uniform laterally and this is the very fastest part we're talking about, of what can be seen.

There is ejecta visible on the East face ahead of such...
http://the911forum.freeforums.org/wtc-1-diagonal-slice-t193.html
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Re: B&L Revisited - Rigidity and Crush Direction(s)

Postby OneWhiteEye on Sat Nov 07, 2009 6:06 pm

femr2 wrote:There is ejecta visible on the East face ahead of such...
http://the911forum.freeforums.org/wtc-1-diagonal-slice-t193.html

Radically different characteristics. Not that anyone cares, but I'm about to give my wedge of debris model the boot. It will never explain the east side.

Observation is SO far ahead of theory. This thread may seem like a pointless exercise. It may be the case, ultimately. But I really do want to know how many angels can dance on the head of a pin; if possible, whether the number differs for tango, waltz, timewarp, etc.
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Re: B&L Revisited - Rigidity and Crush Direction(s)

Postby femr2 on Sat Nov 07, 2009 7:11 pm

OneWhiteEye wrote:
femr2 wrote:There is ejecta visible on the East face ahead of such...
http://the911forum.freeforums.org/wtc-1-diagonal-slice-t193.html

Radically different characteristics. Not that anyone cares, but I'm about to give my wedge of debris model the boot. It will never explain the east side.

Observation is SO far ahead of theory. This thread may seem like a pointless exercise. It may be the case, ultimately. But I really do want to know how many angels can dance on the head of a pin; if possible, whether the number differs for tango, waltz, timewarp, etc.

I'm open to a rational explanation, but I also like to dance. (Timewarp especially, seeing as it's much more fun than ballroom :) It's just a jump to the left. And then a step to the ri-i-i-i-ight.)

I look forward to the new force equation.
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Re: B&L Revisited - Rigidity and Crush Direction(s)

Postby Major_Tom on Mon Nov 09, 2009 2:55 am

Not that anyone cares, but I'm about to give my wedge of debris model the boot. It will never explain the east side.

Observation is SO far ahead of theory. This thread may seem like a pointless exercise. It may be the case, ultimately.


Observation is so far ahead of theory.

This means the door is wide open.

This is not a useless exercise. If you do not understand the limitations of the physics it will be used against you. People with PhD's can sell you swamp land in Florida and you wouldn't know the difference.

Your wedge idea and my OOS runaway destruction idea are the only natural collapse theories left. The people advocating natural collapse do not realize that they have no more theories.


Likewise many people who argue for demolition do not understand that there may be the potential for runaway destruction within the WTC 1 and 2 structures.

By introducing a wedge mechanism and/or defining collapse time by the progression of rubblized debris through the OOS sw region we force both sides to look at the issue with new eyes.


Wedge mechanism is not a waste. It is the only natural collapse process left which is consistent with all observables. Even if it is wrong it should serve to open everyone's eyes.

Everyone, from Bazant and Seffen to Ross to Beck, everyone worked the mechanics wrongly. They didn't notice because both sides were making the same fundamental mistakes.

They all should be reading this forum.

Not a waste at all. The door is wide open for a new approach.
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Re: B&L Revisited - Rigidity and Crush Direction(s)

Postby OneWhiteEye on Mon Nov 23, 2009 11:25 pm

Thanks for the words of encouragement, Major_Tom.

Just an aside, so many irons... here's an example (and only an example) of a hypothetical upper block crush-up in a stationary frame of reference:

Image

The same structure crushing up in a frame of reference accelerating downwards at 0.6g:

Image

The green line is displacement of roofline, red is freefall displacement (not too meaningful in 2nd graph), teal is velocity and gray is crush front location. In the accelerated frame, there's about 7 meters of displacement at 3 seconds, not much.
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