Can Airliner Impacts Destroy Towers?

[Patrick Brown]

This was researched by a one time member here. I figure it might be of interest here:

{start copy}

Researched by chek
Discussion thread for this entry: http://911evidencebase.16.forumer.com/posting.php?mode=editpost&p=9

OK then - first thing I'd like to establish is that the WTC Towers were designed to withstand full on 600mph impacts by Boeing 707 and Douglas DC- 8 class aircraft (the largest in existence when the Towers were designed) and very similar, certainly in the same class as B767's.

A lot of misinformation has been bandied around that the WTC towers were only meant to withstand a slow, approach speed impact by an airliner on finals, and they 'forgot' to allow for the fuel being carried. If you've heard this fable, you've heard wrong.

OF COURSE fuel load was factored in with a modern airliner crash - how would it not be. How were these theoretical jetliners meant to be delivered into the towers? By Federal Express? Or dumper truck?

"Engineers had to consider every peril they could imagine when they designed the World Trade Center three decades ago because, at the time, the twin towers were of unprecedented size for structures made of steel and glass.

"We looked at every possible thing we could think of that could happen to the buildings, even to the extent of an airplane hitting the side," said John Skilling, head structural engineer. "However, back in those days people didn't think about terrorists very much."

Skilling, based in Seattle, is among the world's top structural engineers. He is responsible for much of Seattle's downtown skyline and for several of the world's tallest structures, including the Trade Center.

Concerned because of a case where an airplane hit the Empire State Building, Skilling's people did an analysis that showed the towers would withstand the impact of a Boeing 707.

"Our analysis indicated the biggest problem would be the fact that all the fuel (from the airplane) would dump into the building. There would be a horrendous fire. A lot of people would be killed," he said. "The building structure would still be there."
Seattle Times, Business: Saturday, February 27, 1993

John Skilling of Worthington, Skilling, Helle and Jackson, senior designer of the Trade Centre Towers.

“Our analysis indicated the biggest problem would be the fact that all the fuel (from the airplane) would dump into the building. There would be a horrendous fire. A lot of people would be killed.” But, he says, “The building structure would still be there.”

John Skilling who was one of the two structural engineers responsible for designing the Trade Centre, recounts his people having carried out an analysis which found the twin towers could withstand the impact of a Boeing 707.
[Seattle Times, 2/27/1993]

The analysis Skilling is referring to is likely one done in early 1964, during the design phase of the towers. A three-page white paper, dated February 3, 1964, described its findings: “The buildings have been investigated and found to be safe in an assumed collision with a large jet airliner (Boeing 707—DC 8 ) travelling 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.”

Below is a link to photostat images of that White Paper.

http://pilotsfor911truth.org/WTC.html

Skilling is known for many positive accomplishments. He is credited with the structural design of more than 1,000 buildings in 36 states and 27 countries, including the Pacific Science Center for the 1962 World’s Fair, the original 50-story Seafirst Building and Seattle’s tallest building, the 76-story Columbia Seafirst Center.

“The building was designed to have a fully loaded 707 crash into it. That was the largest plane at the time. I believe that the building probably could sustain multiple impacts of jetliners because this structure is like the mosquito netting on your screen door -- this intense grid -- and the jet plane is just a pencil puncturing that screen netting. It really does nothing to the screen netting”.
Frank A. Demartini, on-site construction manager for the World Trade Center, spoke of the resilience of the towers in an interview recorded on January 25, 2001.
http://video.google.com/videoplay?docid=-3281135121622917423

Information on the Boeing 707. By the mid 1960's, the 707-320B model was the most commonly used for long haul flights.
http://www.boeing.com/commercial/707family/product.html

Information on the Boeing 767
http://www.boeing.com/commercial/767family/pf/pf_200prod.html

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 can carry 23,000 gallons of fuel.
The Boeing 767 can 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.

While not identical twins, it can be clearly seen that both types are in the same class in terms of size, weight and performance, if not economy.

Formula for calculating kinetic energy: KE = (mass x velocity^2)/2 or 1/2 mv^2

The kinetic energy released by the impact of a Boeing 707-320B at cruise speed is
= 0.5 x 336,000 x (890) ^2/32.174
= 4.136 billion ft lbs force (5607MJ).

The kinetic energy released by the impact of a Boeing 767 at cruise speed is
= 0.5 x 395,000 x (777)^ 2/32.174
= 3.706 billion ft lbs force (5024MJ).

We can see that the 2001 disaster actually had less impact than Skilling allowed for.

Of even more interest:
"The North Tower impact has been calculated at 2540MJ, and the South Tower at 3658MJ"
(Chapter 4 Aircraft Impact Damage p37 NIST’s Tomasz Wierzbicki , Director of the impact and crashworthiness team)
which is well below Skilling’s calculated figure.

On February 13, 1965, real estate baron Lawrence Wien called reporters to his office to charge that the design of the Twin Towers was structurally unsound. Many suspected that his allegation was motivated by a desire to derail the planned World Trade Center skyscrapers to protect the value of his extensive holdings, which included the Empire State Building. In response to the charge, Richard Roth, partner at Emery Roth & Sons, the architectural firm that was involved in designing the Twin Towers, (the architects were Minoru Yamasaki Associates of Rochester Hills, Mich) fired back with a three-page telegram containing the following details.

”The structural analysis carried out by the firm of Worthington, Skilling, Helle & Jackson is the most complete and detailed of any ever made for any building structure. The preliminary calculations alone cover 1,200 pages and involve over 100 detailed drawings.

Because of its configuration, which is essentially that of a steel beam 209ft deep, the towers are actually far less daring structurally than a conventional building such as the Empire State Building where the spine or braced area of the building is far smaller in relation to its height.

The building as designed is sixteen times stiffer than a conventional structure, The design concept is so sound that the structural engineer has been able to be ultra-conservative in his design without adversely affecting the economics of the structure”.
City in the Sky, Times Books, Henry Hold and Company, LLC, 2003, page 133

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[THETRUTHWILLSETU3]

What's your point?

[Fallious]

It's great to see that the impact force actually comes out significantly less for the 767. I shall be using this resource frequently.

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[marky 54]

a post with evidence that is easy to understand and well laid out and dosnt rely on second hand clips, good post.

[Dogsmilk]

[Patrick Brown]

For those that haven't got time to read the whole article the thrust of it is that it's unlikely that the aircraft impacts caused the twin towers to collapse. Now I'm not saying this is a fact but it is compelling and a necessary part of the CD theory. If it's possible to state beyond reasonable doubt that the twin towers would not have collapsed due to the aircraft impacts we have to factor in another cause i.e. Explosives of some kind!

For those that believe only a minimal amount of explosives (possibly thermite) would have been needed the power down of the south tower a couple of days before 911 becomes very suspicious. The critics have suggested that the kinetic energy of the collapsing top section of the twin towers explains their fall speeds. Whereas this may explain certain phenomena it may help the CD theory by suggesting that only a minimal amount of explosives (again possibly thermite) was needed to be set (within core columns accessed from the elevator shafts) over a minimal number of floors (let three to five) so as to initiate collapse.

Remember the radio mast on the north tower moves a split second before the upper floors start to collapse. This points to the core columns failing although it seem hard to believe that such a cataclysmic failure of all the core columns could happen within a few seconds of each other. Remember the the core columns were braced so as to limit sideways movement as well as being protected by fireproofing.

This animated gif shows show the symmetrical failure of the core columns of the north tower:



Again watch the symmetrical collapse on this vid clip noting the uniformity and speed of collapse:


Link


Now the official theory would argue that the outer columns (approx 250) are bearing the extra loads as the core columns weaken prior to collapse. So the core may be twisting and buckling with no apparent observable effect at the exterior of the towers. Now this is a possibility and can not be ruled out but the same effect would have been achieved through the use of a minimal amount of explosives (or thermite) placed within the core columns across several floors.

OK so there may be some doubt about the CD theory but what about the lack of fighter planes on 911? There are two possibility's:

1. The American air force/government allowed the Boeing's to impact the towers.

2. The terrorists chose the day of the FEMA terror drill so as to maximize confusion which resulted in the lack of scrambled air support on the morning of 911.

[THETRUTHWILLSETU3]

Mods please move this poster to critics corner.

Is it not the case that anyone who in any way validates the OCT goes there or is Patrick Brown an exception?

[Patrick Brown]

[QuitTheirClogs]

My understanding is that NIST have split each collapse into two separate events – the initiation of the collapse and the freefall collapse itself. They’ve put forward an explanation for the initiation, but haven’t even attempted to explain the freefall.

http://wtc.nist.gov/pubs/factsheets/faqs_8_2006.htm


Their explanation of the initiation looks feeble, because:

1) it requires temperatures of up to 1,000 deg C – and these temperatures would need to be sustained for some considerable time

[Patrick Brown]

[rodin]

[Snowygrouch]

TWSU3,
You said someone who posted a very good article on why the towers SHOULD have stood after being hit with planes should have their post moved to critics corner...

Look I dont mean to be impolite here but ARE YOU A TOTAL MORON?

Seriously do you have a fundamental inability to process information and facts?

Your behaviour is utterly without any sensible reason or method. I`m so stunned by such a lunatic comment I`m going to have to sit down for a while...*whew*.

C.

[rodin]

[THETRUTHWILLSETU3]

[QuitTheirClogs]

Hi Partrick;

I'm not familiar with OCT - could you give me a brief overview?

When I look at the evidence from the towers collapse, I see a massive energy deficit. And this deficit is so large that I don’t see the point in people going too far down the road of trying to quantity it. Just saying there is a large, unexplained energy deficit is sufficient.

I agree this implies that a large amount of explosives must have been planted in the towers, and this leads to questions of how and when. For which we can speculate, but we can’t claim to know or have compelling evidence.

I think in general we should be stressing the implausibility of any explanation which doesn’t include explosives. And stressing that NIST don’t actually have an explanation for the freefall is a good place to start.

Different aspects of the collapse will hit home with different people. This summer I watched – from my office window – someone spending a few days attacking concrete foundations with a jackhammer. Concrete does NOT pulverise! Or not without the help of explosives it doesn’t.

[Patrick Brown]

OCT = Official Conspiracy Theory i.e. the official line of the American government.

I think tons of steel and other debris impacting downwards can explain the pulverization of much of the concrete. Also it's not true that all the concrete was turned to dust.

[QuitTheirClogs]

[Patrick Brown]

[QuitTheirClogs]

[Patrick Brown]

[brian]

There is nothing really difficult about this as Quittheirrclogs has demonstrated and Andrew Johnson demonstrated from the outset.

Freefall = no resistance.

Pulverisation = massive resistance.

That cannot be resolved in a gravity collapse scenario - it is quite literally impossible.

Therefore the official "explanation" is a lie.

Patrick Brown - you are searching for an answer that cannot exist.

The how of the collapse is of secondary importance and speculation a handicap to the exposure of the lie and the case for for a genuine inquiry.

Expose the lie first and foremost.

[Patrick Brown]

[QuitTheirClogs]

[brian]

Patrick, you are muddled.

What I said was -

Freefall = no resistance.

Pulverisation = massive resistance.

That cannot be resolved in a gravity collapse scenario - it is quite literally impossible.

You then say -

"Sorry but you're wrong as near free fall speeds are often observed as a result of CD."

That is what I am saying - gravity alone cannot account for the nature of the collapse.

Apart from the obvious, common sense should tell us that given the construction of the towers - decreasing strength of beams the higher they got due to decreased loading - the upper portion collapsing on the lower portion should have resulted in the weaker upper portion being destroyed and arrested by the stronger lower portion.

This has been dealt with by Gordon Ross and has not been refuted -

How the Towers were Demolished

http://gordonssite.tripod.com/id2.html

Reply to Dr. Greening

http://www.worldtradecentertruth.com/articles/Article_3_RossReply.pdf

And apart from all that we can all see for ourselves from the videos that much of the mass of the upper portion fell outwith the peimeter of the buildings making the case for the hammer effect of the upper portion a non starter.

[kbo234]

[kbo234]

[Patrick Brown]

[kbo234]

[kbo234]

[rodin]

I have seen footage where debris is clearly falling faster than the tower itself. I thought this must cast some doubt on the free-fall speed which I had previously accepted as gospel, since debris (falling at free fall speed) was overtaking the building.

I have been re-examining collapse footage. I think some debris started falling before the building began to collapse, hence had more time to accelerate. In this video you can see debris ejected from the fracture level falling at the same rate as the top of the building. Hence WTC2 DID fall at free-fall speed. This is hard evidence after all, just from this footage alone.



Scroll down this link and click on the picture as shown above to play the video in Media Player

http://www.plaguepuppy.net/public_html/collapse%20update/

I have changed my mind. Free fall collapse of WTC2 goes into G911 after all.