WTC Collapses

[scott3x]

What are you talking about? You may wish to quote what you're responding to a little more often; the way it is right now, it frequently makes it -very- hard to understand what you're talking about a fair amount of the time.

you cant understand my posts?

When you don't quote I can definitely get confused; sometimes I'm not even sure who you're talking -to-, although since we seem to be about the only people talking right now that part isn't too hard to figure out right now :-p.

[scott3x]

Perhaps it was sprayed on as I believe Headspin has suggested.

incredible. i am speechless.

Headspin went into detail a while ago. Perhaps I can dig up his arguments on the subject at some future date...

[Uno Hoo]

Poll is flawed by incompleteness.

What about: Keenly interested but yet undecided?

You don't think of that? You try to put up skewed poll?!

Shame on you!

[Uno Hoo]

Theme keeps popping up in this thread about steel melting or not. Fact is, steel begins seriously losing strength at temperature far below melting temperature. Steel loses a lot of its strength many hundred degrees below melting point.

My post has no purpose to say that it was an inside job or that it was not an inside job. My post is only to say that when you think about steel collapsing, it can lose enough strength to fall down far below melting point.

You don't need to see molten steel pouring out of wall to conclude that steel was too weak to survive.

[Headspin]

Theme keeps popping up in this thread about steel melting or not. Fact is, steel begins seriously losing strength at temperature far below melting temperature. Steel loses a lot of its strength many hundred degrees below melting point.

My post has no purpose to say that it was an inside job or that it was not an inside job. My post is only to say that when you think about steel collapsing, it can lose enough strength to fall down far below melting point.

You don't need to see molten steel pouring out of wall to conclude that steel was too weak to survive.

what you say is well known to most people here, but the question is "why did the steel melt".
you seem to be responding to the strawman statement "the steel must have melted for the building to fall down"

so,
why did the steel melt?

http://www.youtube.com/watch?v=afZaK...eks-after-911/

or more precisely,
what caused temperatures of 5000 F, twice that of the melting point of steel?

http://www.journalof911studies.com/a...CHighTemp2.pdf

[scott3x]

Poll is flawed by incompleteness.

What about: Keenly interested but yet undecided?

You don't think of that? You try to put up skewed poll?!

Shame on you!

I bet Stryder simply didn't think of it, but good point. I've now made a new poll, concerning all of 9/11, that includes that certain elements of 9/11 were questionable. There's also an "other" because when it comes to things like this, I figure there may well be a fair amount of people who simply didn't like any of the other 6 options.

[scott3x]

Kevin Ryan's expertise and UL's and NIST's tests of -real- steel, Round 2

This post is in response to the 2nd and final part of shaman_'s post 1417 in this thread.

I agree. However, you continue to ignore the fact that he did much more then work with water. He details his research during his time working at Underwriter Laboratories, as well as after. You may want to read about it in his article "Propping up the War on Terror", starting at his sub heading "NIST and Underwriters Laboratories". I'll even give you the intro in the hopes that you will read further:
In August 2004, Underwriters Laboratories evaluated the Pancake Theory by testing models of the floor assemblies used in the WTC buildings. Despite all the previous expert testimony, the floor models did not collapse. NIST reported this in its October 2004 update, in a table of results that clearly showed that the floors did not fail and that, therefore, pancaking was not possible.14 NIST more succinctly stated this again in its June 2005 draft report, saying: "The results established that this type of assembly was capable of sustaining a large gravity load, without collapsing, for a substantial period of time relative to the duration of the fires in any given location on September 11th."15

More meaningless spam

It's not 'meaningless spam'. Did you even read it?

intended to somehow distract from the subject that Kevin Ryan was not involved in the testing of steel assemblies.

You erroneously believe that if he wasn't involved in the testing of steel assemblies he must therefore not be an expert on the subject of the WTC steel. It's an erroneous belief and if you actually -read- what Kevin was saying instead of simply calling it spam you might realize this.

I agree that before 9/11 he was indeed not an expert on the WTC steel. This changed, however, when he realized that the company wherein he was a manager was deeply involved in certifying the quality of the steel floor assemblies within the WTC buildings;
at that point, he began to seriously research the issue and question the relevant people in Underwriter Laboratories concerning this issue.

None of those things make him an expert on the steel.

I contend that they do.

Your religion is stopping you from comprehending such a simple and small point.

I could through the same banal point at you (your religion, etc., etc.), but I'm not into banalities. Kevin Ryan is someone who has written peer reviewed papers on the subject of the WTC collapses. The fact that he wasn't testing the steel assemblies doesn't lessen the fact that he knows his stuff in regarding to the WTC steel.

Ratings aside, I have already stated that a test was done with essentially no fireproofing on it. It didn't collapse either.

You have been shown many examples of steel weakening in a fire that some vague and disingenuous reference to a test with ‘essentially no fireproofing’ is not good enough. Perhaps in your mind it is.

Weakening does not equal collapsing. There have been no test results of actual WTC type steel collapsing due to fire; this, despite the fact that some of the tests were under conditions significantly worse then was predicted to actually be the conditions within the WTC buildings at the time of the fires.

Ratings aside, I have already stated that a test was done with essentially no fireproofing on it. It didn't collapse either. Tony mentions that NIST even did a test with no fireproofing at all; apparently they claimed it wasn't a 'real' test and never revealed the results. If steel with essentially no fireproofing didn't collapse and they decided not to reveal the results with on the 'not really a test' steel with -no- fireproofing at all, I think we can all guess as to why they're not so keen on releasing those results.

5 inches of fireproofing is not ‘essentially no fireproofing’.

Where did you get this '5 inches' number from? I certainly didn't provide it.

How was the test set up? What are the details? What didn’t collapse? What were the temperatures?

I'd like to know the answers to that myself. Perhaps I can find out.

In the Cardington tests the unprotected column started buckling when it reached 670C.

Even in the very high temperatures reached in the Cardington tests, the columns didn't collapse. I don't understand why you can't see just how important that is; it means that even if the steel had been unprotected pre collapse, the WTC buildings shouldn't have collapsed.

[scott3x]

Mackey's and NIST's fluff arguments

This post is in response to the 1st part of shaman_'s post 1418 in this thread.

That was the statement that Mackey was rebutting! You can’t respond to it with the very comment he was responding to!

Sure I can.

Scott, Imagine that you posted a criticism of some of Mackey’s claims, as a rebuttal I just cut and pasted the original claims that were being criticized. That is what you are doing. That is closer to trolling than discussing.

That depends. Consider:
Kevin Ryan says that 2+2=4

Ryan Mackey says that no, 2+2=17.

I come in and simply state that Kevin's original answer is right, as it follows the laws of mathematics, where Mackey's clearly didn't.

Silly examples aside, the point at hand is that you think is that when discussing a particular article, any criticism of that article can be responded to by posting the article again.

The example isn't silly- I'm trying to explain to you how Ryan Mackey's counter was so flawed that all one has to go back to what he's countering to realize this.

Frequently, Mackey Ryan's "rebuttal" are nothing more then fluff; sometimes even I can see that.

No one is convinced that you are able to assess Mackey’s writing yourself.

So far, the only person who I'm sure isn't convinced is you.

The point is that flashovers are instant. 120 and 600 seconds, aka 2 and 10 minutes, is way longer then a flashover would take.

Whether you want to call it a flashover or not, NISTs workstation tests noted periods over high temperatures (800+) for much longer than two minutes.

NIST's workstation tests were clearly tweaked, as Steven Jones and others have made clear.

I don't think you even know what we are discussing. You just throw the ‘as Steven Jones made clear’ for good measure.

I'm discussing the following passage from Steven Jones' paper, Why Indeed Did the WTC Buildings Collapse?:
*******************
The NIST report makes for interesting reading. The less severe cases based on empirical data were discarded because they did not result in building collapse. But ‘we must save the hypothesis,’ so more severe cases were tried and the simulations tweaked, as we read in the NIST report:

The more severe case (which became Case B for WTC 1 and Case D for WTC 2) was used for the global analysis of each tower. Complete sets of simulations were then performed for Cases B and D. To the extent that the simulations deviated from the photographic evidence or eyewitness reports [e.g., complete collapse occurred], the investigators adjusted the input, but only within the range of physical reality. Thus, for instance,…the pulling forces on the perimeter columns by the sagging floors were adjusted… (NIST, 2005, p. 142; emphasis added.)

The primary role of the floors in the collapse of the towers was to provide inward pull forces that induced inward bowing of perimeter columns. (NIST, 2005, p. 180; emphasis added.)

How fun to tweak the model like that, until the building collapses — until one gets the desired result. But the end result of such tweaked computer hypotheticals is not compelling, sorry gentlemen. Notice that the “the pulling forces on the perimeter columns by the sagging floors were adjusted” (NIST, 2005, p. 142; emphasis added) to get the perimeter columns to yield sufficiently — one suspects these were “adjusted” by hand quite a bit — even though the UK experts complained that “the core columns cannot pull the exterior [i.e., perimeter] columns in via the floor.” (Lane and Lamont, 2005; emphasis added.)
*******************

Don't you think it rather curious that the -physical- models of the WTC steel never collapsed?

The workstation tests did not involve testing steel for collapse scott.

No kidding. I'm talking about the -physical- steel tests that NIST did; in those tests, not a single steel beam collapsed. As you may recall, Tony said that they even tested steel without any fireproofing at all, but it didn't collapse either.

A roaring fire over 800C for twenty minutes can do quite a bit of damage to a building.

It wouldn't do much to steel on the few floors of WTC building that had the fires,

Steel is only at about 50% of its strength at 600C scott.

2 points:
1- There is little to no evidence that the office fires could have gotten the steel to reach those temperatures.

2- Even at those temperatures, the steel wouldn't have collapsed. You have only to look at your Cardington tests to see the veracity of this. The irony is that even the NIST computer simulations don't have the twin towers collapsing- they only get to 'poised to collapse'.

but perhaps to a weaker structure, such as the Windsor Tower in Madrid, it could produce a gradual partial collapse.

Yes never the mind the CONCRETE CORE!

Sigh. The concrete core would have made it weaker, not stronger.

[scott3x]

NIST's fluff computer simulations

This post is in response to the 2nd and final part of shaman_'s post 1418 in this thread.

You have not mentioned the other fire tests presented to you either.

What fire tests are those?

The ones Kenny showed you. He has posted that link at least twice and I have posted it twice. That’s at least four times Scott. Will you pretend that you don't remember?

I'm not pretending anything. Something mentioned 4 times over the course of multiple threads spanning thousands of posts doesn't always leave a mark.

Ignoring evidence without even commenting four times is a little suspicious don’t ya think scott?

Sigh. What evidence am I allegedly ignoring?

The Cardington tests did not simulate the conditions in the WTC buildings. This is something you have failed to note.

The last test was fueled only by office equipment......

I believe psikeyhackr has covered this issue- the Cardington fire tests were done to a building within a building. Ofcourse, the real clincher here is that even though the fires were by all the accounts I've heard, much hotter then what the WTC office fires were thought to have been, the building still didn't collapse.

There -were- tests done that -did- simulate what happened in the WTC buildings. The results of these tests were not favourable to NIST's 'office fires' theory, however- none of those steel beams collapsed. The only way NIST could get the twin towers to even -appear- 'poised to collapse' was to tweak a computer model; reality simply wouldn't cooperate. In other words, they did some snazzy special effects on a computer, where cartoon physics can most certainly apply.

Which tests are you talking about. Explain to me without cutting and pasting.

I'm not going to put into my own words what has already been said quite well by Kevin Ryan. If you don't want to read it just because it's not in my 'own words', so be it. Once again, from Kevin Ryan's article Propping up the War on Terror:
In August 2004, Underwriters Laboratories evaluated the Pancake Theory by testing models of the floor assemblies used in the WTC buildings. Despite all the previous expert testimony, the floor models did not collapse. NIST reported this in its October 2004 update, in a table of results that clearly showed that the floors did not fail and that, therefore, pancaking was not possible.14 NIST more succinctly stated this again in its June 2005 draft report, saying: "The results established that this type of assembly was capable of sustaining a large gravity load, without collapsing, for a substantial period of time relative to the duration of the fires in any given location on September 11th."15

There is no solid evidence that much of the fireproofing was removed in the WTC buildings prior to collapse. Explosives could certainly have removed it during collapse, however.

The collapse alone would have removed some.

Perhaps; we're talking pre collapse though.

Think about it scott. You see explosives and megasuperdooperthermite as the instant answer for everything.

I've been debating here since August; the answers have been far from 'instant'. The fact that you can't seem to find any reasonable objections to the possibility that thermite/thermate was used is, I believe, quite telling.

But as usual you are trying to deflect from the point at hand. You keep mentioning tests by UL done on complete fireproofed assemblies. Not relevant.

Tony has mentioned that some tests were done where no fireproofing was used at all, but that NIST refused to reveal the results, claiming it was just a calibration test. I believe you yourself have mentioned that in the Cardington fire tests, which apparently reached temperatures much higher then what the WTC office fires were calculated by FEMA to reach, no fireproofing was used, and yet, those beams didn't collapse either.

Alright, I'll assume you're right on that one for now. However, the Cardington tests were not modelled after the WTC buildings

An office fire is an office fire.

A building is a building too. However, this doesn't mean that all office fires, or buildings for that matter, are one and the same. The point isn't all that important anyway, as the Cardington steel beams didn't suffer collapse either.

1000C fires does not equal 1000C steel.

In the Cardington tests the temperature of the steel was only marginally that of the atmosphere. You guys refuse to accept this.

Apparently neither you nor Headspin could find the raw data for this. However, even assuming it's true, the fact remains that even at those scorching temperatures, the Cardington steel beams didn't collapse.

Fine. The temperatures in the Cardington tests were way above what the WTC fires were at, but ok.

That is an assertion based on your faith. As I have said, one of the tests was fueled only by office materials and it reached near 1000C.

Alright, I'll assume you're right on that one for now. However, the Cardington tests were not modelled after the WTC buildings- 1000C fires does not equal 1000C steel. Not to mention the fact that Kevin Ryan has stated that there is no evidence that even the WTC fires reached those temperatures.

I can't believe you are still saying this. Kevin Ryan saying something does not constitute evidence.

True. However, Kevin Ryan backs up his claims with solid evidence, something that Mackey doesn't concern himself much with. From Jiff Hoffman's Review of 'A New Standard For Deception: The NIST WTC Report'- A Presentation by Kevin Ryan:

Ryan notes that steel temperatures lag behind gas temperatures in both time and magnitude, and that none of the official reports have performed thermodynamic calculations about the probable steel temperatures. Ryan's own calculations show that steel temperatures in the impact zones probably did not exceed 600 F.

[scott3x]

Access Restrictions

This post is in response to leopold99's post 1419 in this thread.

what does this have to do with denial to the debris field?
access to the debris field was available to people.
the cameramen from camera planet was on site THAT VERY NIGHT.
so don't tell me people were refused access.

On September 26th, then-Mayor Rudolph Giuliani banned photographs of Ground Zero.

a full 15 days AFTER 9/11 happened.

I never said that they banned pictures right away.

plus, banning photographs IS NOT the same as banning people.

I get to that below...

6 An account by an anonymous photographer (AP), who took the photographs at the end of the Ground Zero photographs page, describes the treatment of this citizen investigator.

anonymous? yes indeed. if you want the truth about 9/11 scott then you can't play the "anonymous" crap.

I'm not 'playing' anything. I'm simply quoting what the 9/11 Research site said.

regardless, you haven't shown that people were denied access to the debris field.

I was just getting started. From 9/11 Research's article, Access Restrictions- The Closure of Ground Zero to Investigators:
*******
While the steel was being removed from the site of the three largest and most mysterious structural failures in history, even the team FEMA had assembled to investigate the failures -- the Building Performance Assessment Team (BPAT) -- was denied access to the evidence. 1 The Science Committee of the House of Representatives later identified several aspects of the FEMA-controlled operation that prevented the conduct of an adquate investigation: 2

* The BPAT did not control the steel. "The lack of authority of investigators to impound pieces of steel for investigation before they were recycled led to the loss of important pieces of evidence."
* FEMA required BPAT members to sign confidentiality agreements that "frustrated the efforts of independent researchers to understand the collapse."
* The BPAT was not granted access to "pertinent building documents."
* "The BPAT team does not plan, nor does it have sufficient funding, to fully analyze the structural data it collected to determine the reasons for the collapse of the WTC buildings."

Gene Corley complained to the Committee that the Port Authority refused to give his investigators copies of the Towers' blueprints until he signed a wavier that the plans would not be used in a lawsuit against the agency. 3
...
*******

The article goes on. You may want to take a look.

you haven't shown that uneploded bomb material was found in the debris field.

Headspin is the one who made that allegation.

about headspin,
if he wants to get all bent out of shape over an error on my part then that's HIS problem, not mine. i already told him i couldn't view the video.

Ok.

[scott3x]

The Structural Engineer for the Twin Towers

This post is in response to leopold99's post 1529 in this thread.

I assume you mean Leslie Robertson. Kevin Ryan has stated that, NOVA's claim notwithstanding, Leslie Robertson has never claimed to have originated the design of the twin towers. Here is Kevin Ryan's remarks in his essay, "Propping up the War on Terror":
Perhaps most compelling for me were the words of a genuine expert on the WTC. This was John Skilling, the structural engineer responsible for designing the towers.17 (The NOVA video, incidentally, gave this credit to Leslie Robertson. But Robertson, who never claimed to have originated the design, was only a junior member of the firm [Worthington, Skilling, Helle and Jackson], and Skilling was known at the time to be the engineer in charge.) In 1993, five years before his death, Skilling said that he had performed an analysis on jet plane crashes and the ensuing fires [emphasis mine] and that "the building structure would still be there."18

i never originated the design for computers but i've designed my own.

Fair enough...

there is a difference between "concept" and "design" you know.

I agree.

leslie designed WTC 1 and 2, the concept for the buildings could easily been to someone elses credit.

Kevin Ryan stated that Skilling originated the design of the twin towers. He didn't say that Skilling came up with the concept and Leslie designed them.

In the famous 3 page white paper, which I believe was written by Skilling and mentions the 1,200 page preliminary calculations that have apparently gone missing, John Skilling is mentioned as the Structural Engineer for the World Trade Center. Leslie Robertson isn't mentioned at all.

[scott3x]

Comparing the Boeing 707 to the 767

This post is in response to MacGyver1968's post 1533 in this thread.

Note the speeds. The planes that hit the towers were traveling at much faster speeds...almost 3 times. The 767 is slightly larger, but was traveling 2-3 times faster...roughly doubling or tripling the impact force.

Actually, the 767s were going slower then the cruising speed of 707; 9/11 Research makes a powerful case that the buildings were fully capable of handling the impacts of the 767s in its article called Towers' Design Parameters.

From the Fema report, the buildings were designed to be hit at 180 mph.

Then the FEMA report wasn't doing its homework, which seems to be the norm in all these government studies. Thank goodness some people do, such as 9/11 Research. I hope that you'll take a look at 9/11 Research's excellent work on the subject, Towers' Design Parameters, one day.

I've asked you repeated times not to do this. Stop making me do the work to respond to your post. Don't just post the link...at least quote the relevant part here.

I've found it frequently better to first only put up the link; many have accused me of spamming when I excerpt relevant portions of a link. So I've been cutting back a bit on excerpting right away, to see if the person I'm talking to actually wants to listen to my argument or whether they simply likes to lecture :-p.

Anyway, some important facts, taken from whatreallyhappened.com's Boeing 707 - 767 Comparison article:
********************
The maximum takeoff weight for a Boeing 707-320B is 336,000 pounds.
The maximum takeoff weight for a Boeing 767-200ER is 395,000 pounds.

The wingspan of a Boeing 707 is 146 feet.
The wingspan of a Boeing 767 is 156 feet.

The length of a Boeing 707 is 153 feet.
The length of a Boeing 767 is 159 feet.

The Boeing 707 could carry 23,000 gallons of fuel.
The Boeing 767 could carry 23,980 gallons of fuel.

The cruise speed of a Boeing 707 is 607 mph = 890 ft/s,
The cruise speed of a Boeing 767 is 530 mph = 777 ft/s.

The Boeing 707 and 767 are very similar aircraft, with the main differences being that the 767 is slightly heavier and the 707 is faster.

Since the Boeing 707 had a higher thrust to weight ratio, it would be traveling faster on take-off and on landing.
The thrust to weight ratio for a Boeing 707 is 4 x 18,000/336,000 = 0.214286.

The thrust to weight ratio for a Boeing 767 is 2 x 31,500/395,000 = 0.159494.

In all the likely variations of an accidental impact with the WTC, the Boeing 707 would be traveling faster. In terms of impact damage, this higher speed would more than compensate for the slightly lower weight of the Boeing 707.

In conclusion we can say that if the twin towers were designed to survive the impact of a Boeing 707, then they were necessarily designed to survive the impact of a Boeing 767.
********************

It mentions one thing at the beginning of the article that I have doubts about, however:
In 1966, Robertson designed the structural elements of the WTC towers to withstand the impact of the largest airliner then in service, the Boeing 707.

It offers no citation, however. It was my understanding that Skilling did this, not Robertson. Furthermore, 9/11 Research's article Towers' Design Parameters, brings up the 1964 white paper that I have mentioned in the past, which states:
The buildings have been investigated and found to be safe in an assumed collision with a large jet airliner (Boeing 707—DC 8) traveling at 600 miles per hour. Analysis indicates that such collision would result in only local damage which could not cause collapse or substantial damage to the building and would not endanger the lives and safety of occupants not in the immediate area of impact. 4

[John99]

In conclusion we can say that if the twin towers were designed to survive the impact of a Boeing 707, then they were necessarily designed to survive the impact of a Boeing 767.

We already went over this.

Theoretical designs are all well and good but they are just theories. In the end they could not withstand the 10,000 gallon plus of burning fuel seepage. This in turn caused the pancake effect which has happened with numerous tower and hi rise collapses. That is known as precedence.

This was end result.

[John99]

I see one of those links you cited is looking for 50K in donations. Wonder what for? Also books, dvd's, stickers for sale. This seems to be a common thread in Tooferdom.

[scott3x]

Anyway, some important facts, taken from whatreallyhappened.com's Boeing 707 - 767 Comparison article:
...
In conclusion we can say that if the twin towers were designed to survive the impact of a Boeing 707, then they were necessarily designed to survive the impact of a Boeing 767.

We already went over this.

Theoretical designs are all well and good but they are just theories.

These theories were tested post 9/11 with real steel beam models. There isn't a single report of any of these steel beams collapsing, not even from NIST's 'calibration' test of a steel beam without fireproofing.

In the end they could not withstand the 10,000 gallon plus of burning fuel seepage.

The evidence strongly suggests otherwise.

This in turn caused the pancake effect which has happened with numerous tower and hi rise collapses. That is known as precedence.

Actually, no high rise has suffered a complete collapse due to planes and/or fires alone before or since it allegedly happened on 9/11.

[scott3x]

I see one of those links you cited is looking for 50K in donations. Wonder what for?

Not sure which link you're referring for, but I'm assuming it's so that private investigators can continue to have the time to investigate the many issues concerning 9/11 or perhaps to further disseminate the truth concerning what happened on 9/11.

Also books, dvd's, stickers for sale. This seems to be a common thread in Tooferdom.

There is nothing wrong with making a bit of money from the hard work that has been done to investigate what really happened on 9/11. Unlike the government's investigators, the 9/11 truth movement has had to rely on donations and sales of books, etc., in order to make it financially viable to put in the amount of time that many in the truth movement put in. I personally have never made a cent on it, but I certainly wouldn't mind doing so- as you know, my financial picture isn't exactly rosy :-p.

[scott3x]

Had to have been more then one bomb

This post is in response to leopold99's post 1535 in this thread.

Then the FEMA report wasn't doing its homework, which seems to be the norm in all these government studies.

i seriously believe that FEMA could put the phrase " it was a bomb" at the end of their report and you'll be waving it around telling everyone how accurate the investigation was.

Your belief is mistaken. There certainly had to have been a great deal more then a single bomb in the building in order for them to collapse in the way that they did.

[psikeyhackr]

We already went over this.

Theoretical designs are all well and good but they are just theories. In the end they could not withstand the 10,000 gallon plus of burning fuel seepage. This in turn caused the pancake effect which has happened with numerous tower and hi rise collapses. That is known as precedence.

This was end result.

.
This is a case of even denying the official source. The NIST admits a large percentage of the jet fuel exploded in the impact and in the case of the south tower this can be seen to occur OUTSIDE of the building.

Even the NIST rejects the pancake effect in the WTC. Lets see you provide links to documentation of TWO of these numerous tower pancaking incidents. I want to see that they were STEEL FRAMED high rises.

psik

[Tony Szamboti]

Comparing the Boeing 707 to the 767

This post is in response to MacGyver1968's post 1533 in this thread.



I've found it frequently better to first only put up the link; many have accused me of spamming when I excerpt relevant portions of a link. So I've been cutting back a bit on excerpting right away, to see if the person I'm talking to actually wants to listen to my argument or whether they simply likes to lecture :-p.

Anyway, some important facts, taken from whatreallyhappened.com's Boeing 707 - 767 Comparison article:
********************
The maximum takeoff weight for a Boeing 707-320B is 336,000 pounds.
The maximum takeoff weight for a Boeing 767-200ER is 395,000 pounds.

The wingspan of a Boeing 707 is 146 feet.
The wingspan of a Boeing 767 is 156 feet.

The length of a Boeing 707 is 153 feet.
The length of a Boeing 767 is 159 feet.

The Boeing 707 could carry 23,000 gallons of fuel.
The Boeing 767 could carry 23,980 gallons of fuel.

The cruise speed of a Boeing 707 is 607 mph = 890 ft/s,
The cruise speed of a Boeing 767 is 530 mph = 777 ft/s.

The Boeing 707 and 767 are very similar aircraft, with the main differences being that the 767 is slightly heavier and the 707 is faster.

Since the Boeing 707 had a higher thrust to weight ratio, it would be traveling faster on take-off and on landing.
The thrust to weight ratio for a Boeing 707 is 4 x 18,000/336,000 = 0.214286.

The thrust to weight ratio for a Boeing 767 is 2 x 31,500/395,000 = 0.159494.

In all the likely variations of an accidental impact with the WTC, the Boeing 707 would be traveling faster. In terms of impact damage, this higher speed would more than compensate for the slightly lower weight of the Boeing 707.

In conclusion we can say that if the twin towers were designed to survive the impact of a Boeing 707, then they were necessarily designed to survive the impact of a Boeing 767.
********************

It mentions one thing at the beginning of the article that I have doubts about, however:
In 1966, Robertson designed the structural elements of the WTC towers to withstand the impact of the largest airliner then in service, the Boeing 707.

It offers no citation, however. It was my understanding that Skilling did this, not Robertson. Furthermore, 9/11 Research's article Towers' Design Parameters, brings up the 1964 white paper that I have mentioned in the past, which states:
The buildings have been investigated and found to be safe in an assumed collision with a large jet airliner (Boeing 707—DC 8) traveling at 600 miles per hour. Analysis indicates that such collision would result in only local damage which could not cause collapse or substantial damage to the building and would not endanger the lives and safety of occupants not in the immediate area of impact. 4

The 767-200 aircraft which hit the towers were not maximally fueled with 10,000 gallons on them. They also did not have maximum passenger and cargo loads. The NIST estimated that they actually weighed 270,000 to 280,000 lbs.

The 707-320B hit that the 1964 analysis was done for would have been for a 336,000 lb. aircraft doing 600 mph. Even based on the maximum estimated speeds of the 911 aircraft of 473 mph for WTC 1 and 566 mph for WTC 2, the kinetic energy of the 707 impact would have been 93% higher than the North Tower impact and 35% higher than the South Tower impact.

[scott3x]

The 767-200 aircraft which hit the towers were not maximally fueled with 10,000 gallons on them. They also did not have maximum passenger and cargo loads. The NIST estimated that they actually weighed 270,000 to 280,000 lbs.

The 707-320B hit that the 1964 analysis was done for would have been for a 336,000 lb. aircraft doing 600 mph. Even based on the maximum estimated speeds of the 911 aircraft of 473 mph for WTC 1 and 566 mph for WTC 2, the kinetic energy of the 707 impact would have been 93% higher than the North Tower impact and 35% higher than the South Tower impact.

I've heard that the speeds were even lower. Eduardo Kausel, Professor of Civil & Environmental Engineering, MIT, wrote a chapter in The Towers Lost and Beyond, A collection of essays on the WTC by researchers at MIT, in which he calculates the crash speeds of the planes hitting the twin towers. While he admits that he couldn't precisely calculate their speeds, he estimates that the plane hitting the North Tower hit at about 429 mph and the plane hitting the south tower hit at about 503 mph.