when that bomber flew into it back in the 40s I think it was? That was a big plane filled with fuel. You would think buildings of older construction would collapse easier than buildings of newer construction. So how come?

I'm not an expert on WWII bombers, but if I remember right, the WWII was a medium size bomber, and is probably a whole bunch smaller than the 747s that struck the WTC/Pentagon.

What kind of bomber was it? B17? B24? B29!?

Even the biggest of these three is not much compared to a 747 flying at top speed. Another thing to consider is the amount of fuel. 747's carry alot more!

I think that was a B-17, right? Probably not at full throttle, low fuel levels(?). Less mass? Just guessing.

But I saw a show on the Discovery channel that described the methods utilized to build the WTC. It was a light weight steel construction utilizing an external frame. Light weight steel would probably not stand up too well to direct flame impingement. At least not as well as the big steel used in the Empire State building. When the light steel failed it started a chain reaction collapse which increased in speed and scope until the building essentially, for lack of a better term, liquefied.

Does jet fuel burn a lot hotter than 110-120 octane aviation fuel?

Yes, new construction is superior in many ways but when it comes to unleashing big energy on components, I think the big component will take more abuse.

Of course, everything I just said is just a guess and an engineer would better answer this question.

I read an engineering report about why the WTC collapsed, and they seem to share the same sentiments. I think the Empire State Bldg had a lot more concrete.

If I remember correctly, jet fuel is similar to disel fuel, and the some liberals wanted to tax diesel more than gasoline because on a per unit basis, diesel had more energy(i.e. calories), so my conclusion is that jet fuel would probably burn hotter once you ignited it.

There is a TREMENDOUS difference in size of the aircraft. B-25's are by modern standards tiny. A F-14 or F-15 is bigger than a B-25 in length and width and gross something like 3 times as much.

The weight of just the jet fuel alone carried by either one of the planes that hit the WTC was about 4 times the takeoff gross weight of a B-25 like the one that hit the Empire State Building.

Its not possible to say that crash proves the Empire State Building was better constructed because there was never enough flammable material in the wreck to come close to threatening it. The fire was no where near the same size.

Empire State building - hit July 28th, 1945 by a WWII era medium size B-25 bomber.

Bomber dimensions: Span, 67 feet; Length: 53 feet  
Bomber speed: approx 200 mph
Bomber weight: normal gross weight, 27,051 pounds

-------------

World Trade Center - hit September 11th, 2001 by a Boeing 767 airliner.

Airliner dimensions: Span, 156 feet; Length: 159 feet  
Airliner speed: in excess of 500 mph
Airliner weight: over 400,000 pounds (MTOW)

As you can see, there is a huge difference between the aircraft involved.  On a further note, the Empire State Building was built with steel girders and the WTCs were built using a more lightweight steel truss construction which are more susceptible to fire than girders.  Oddly enough, the WTC architects took the Empire State Building / B-25 crash into account when they designed the WTCs.  At the time, they designed the WTCs to be able to withstand the impact of a Boeing 707 - the largest operating airliner at THAT time.  Unfortunately, the 767 was more than it could withstand.

I saw an interview with one of the chief designers of the WTC.

It DID withstand the impact of those planes.

The problem was the effect of the tons of burning fuel on the type of construction.

The fire did the damage that colapsed the buildings, not the impact.

The Frontline piece said that the WTC design is strong at the core and the outside walls. The spans between the core and outside wall are 'flimsy' trusses covered with a fire retardant material. The WTC would still be standing except the impact of the plane  shook off the fire retardant material, then the heat of the fire melted the trusses. Once the spanning trusses melted the building collapsed.

The Empire State building has a complete, internal steel frame throughout. I do not think it would be economic these days to build another Empire State.

{Not minimizing the horrible attack}

Once again the Empire State Building is the tallest skyscraper in NYC which is altogether fitting and proper.

It was the tallest building in the world for 40 years until they built the World Trade Center. The symbol of the city was constructed in only two years - 1930 to 31 and the 1,453 foot colossus instantly became a tourist magnet.

[img]http://www.nyctourist.com/images/empire%20state/es_city_night.jpg[/img]

According to an Port Authority engineer that I know, that is only half right. The building(s) did not collapse because of impact. It is correct when they say that the fire melted the support structure and that caused the collapse.

The disagreement is in how the trusses melted. Halfway through the construction of the WTC (if I remember what I was told, mid 1971) it was made illegal to use the liquid asbestos insulation that was being sprayed on all the steel framing of the building. Because of this the 4000 degree plus insulation barrier that would have protected the steel and at least slowed the melting was only used up to the 61st floor. After that they used a fiberglass coating that could not stand as much heat.

The man who invented the liquid asbestos coating was known to walk past the WTC on a daily basis and before he died in the mid 80's or 90's he would look up at the towers and  comment that if there was a big eneough fire in any floor of that building above 61, it was coming down. And sadly we all know how correct he was

From my research, this ban was just another example of junk science prompting the nanny state to make laws to save us from ourselves.
Yes airborne asbestos dust is lethal, but this was a semi-liquid spackle like spray that became as hard as cement when dry, and was proven to be completely harmless.

For the other engineers out there, please remember that burning jet fuel was not the reason the WTC towers went down. It was the burning furniture & carpet initially set ablaze by the jet fuel that caused the high heat and subsequent structural failures. Jet fuel is basically kerosene and it was a quick flash fire. Unfortunately it set fire to many objects quickly. Think of the fire like a charcoal bbq. The furniture, drapes, carpets, etc. were the charcoal. The jet fuel was like lighter fluid.
 Many people think it was burning jet fuel and this is not correct. It was the insufficient design of the WTC that led to its ultimate structural failure.

The Empire state building is constructed of heavy riveted steel beams covered with (Actually filled in with)a fireproofing concrete asbestos mixture, The outer shell covered in multiple layers of heavy masonry; Just like the old heavy industrial plants of the era (Power plants, steel mills, Etc.) were made.
I worked in  Coal/Oil/Gas fired power plants for 20+ Years & saw many big hot fires in the old boiler rooms, They always held up(When one of them was retired & torn down I witnessed the wrecking ball bounce off).

I belive that if the WTC was constructed like the Empire state building is it would still be standing!
 

IIRC...The fire suppression system in the towers were crippled when the planes struck and the fire was able to spread freely. That is one of the major factors in the collapse also. Saw this on one of the WTC shows.


ByteTheBullet  (-:

Confirmed it was a B-25.

Here's a pic:

[url]http://www.evesmag.com/empirestatecrash.htm[/url]

And a story:

[url]http://www.withthecommand.com/2002-Jan/NY-empireplane.html[/url]

Sure don't make 'em like they used to!!!

I really can't believe that someone had to ask this question.  Probably was asked in order to try to stir up some more paranoid conspiracy crap.

You have to ask yourself why God would allow something like this to happen. He is able to stick his foot out and trip up the people that purport such acts before they happen.


I am certain that anyone working in the Pentagon that pushes paper across their desk that demands that a cruise missile be fired into a "hostile territory" no longer can go home without fear. Its a seriously dangerous job defending this country! Its not for paper pushing, politician promoting bureaucrats! I am happy that anyone in this country seeking to take advantage of another country by using a military strike might now consider it wise to put on a helmet at their desk in the Pentagon. Ronald Reagan was the first funder of Osama bin Laden in his effort against a Soviet attempt to bring order to the Afghan region. He supported the same government in Afghanistan that the Soviets tried to set up, he was trying to prevent Soviet access to warm weather ports.

I'm not so sure on the downplaying of the role of the fuel just as a "starter" in the fire is so accurate.  There were locations where fuel fires continued to burn strongly up until the collapse.  

In the photo below, taken from the west side of 1 WTC, you can see two very concentrated fires putting out plumes of black smoke around the 99th and 105th floors.  Smaller fires (more characteristic of interior furnishings and materials) are visible down to about the 95th floor, and the smoke has spread up to the roof along the north side.  Keep in mind this photo was taken a short time after 2 WTC has collapsed, so the fires have been burning for about 1 hour at this point.

[img]http://home.att.net/~jchoo01/gjs112.jpg[/img]

In my opinion, the push towards structural designs with even greater redundancy and/or increasing fire resistance of structural members is a knee-jerk reaction, partly driven by politics.  Since the buildings stood (in spite of the alleged "defects" in the joist design and fireproofing) at least long enough for the people on floors immediately below the fire floors to evacuate,  I think it is much more important to stress the design of improved means for building occupant egress.

The WTC's fire stairs were located in the center core, so when those became inaccessible, there were no other alternatives for evacuation.  The core was not completely destroyed by the impact (there are many reports of landline telephone conversations with people trapped on upper floors that day).  Hindsight, of course, but stairwells at the outer corners of the building might have provided viable escape routes.

Fuel load of aircraft and combustible materials in the WTC towers caused the collapse.

B-25 less mass / less fuel load and the contents of the Empire State Building were paper, wood, etc.

Heavy aircraft...mucho mass / full cross country fuel load...and the WTC towers were filled with paper, plastics, synthetics, carpet, wall coverings, etc.  Flashover occurs much quicker in modern structures.

Intense fire load on structural members will bring the building down everytime.  We lose many firefighters across the U.S. each year to structural collapse.

be safe guys....

TexasAg
Texas A&M Fire School

Anything that man builds can be destroyed by man.

Jet fuel doesn't burn easy, but it does burn under the right conditions. An explosion caused by a plane full of fuel hitting an object at high speed will cause a fire. Once it starts it's unlikely to stop until the fuel is exhausted.

Yes the Empire State Building is made of heavier materials. But that also means that the building is heavier per cubic. ft. So that the foundation, has to support more weight than a building of equal size, built like the WTC towers.

Once the fire was hot enough so that support columns started failing in the upper part of the building, the upper floors were coming down, and "shock loading" the floors they were on top off. No building will survive if the upper third is dropped 8 ft onto the remaining 2/3's of the building.

Everything has limits.

I was amazed the building survived the initial impacts. Quick someone get a ballistic calculator find out how much force a 400,000 lb plane going at 880 fps has. I'm thinking billions of ft lbs.

The reason those building collapsed, and the Empire State Building didn't, because it was a deliberate, calculated in-humane attack at thousands of innocent people. The Empire State collision was an accident.

I have heard from news reports that the initial crash severed the pipes that carried the water for the fire suppression system.

The big difference between the two collisions is that in the B24 crash, the plane, being smaller, lighter, and slower, largely shattered on the surface of the Empire state building.

As we all saw in the WTC crashes, the fully fueled full throttle jets penetrated the towers then blew up.

As pointed out by others, then the fire burned up the internal supports.

Speaking of junk science....Malaria is still claiming millions of victims and judicious use of DDT is recommended.  This flies in the face of the UN's attempts to ban it's use world wide.  The WHO is schizophrenic about this and although it states that DDT sprayed houses are effective for malaria control, it and other orgs offer grants to foreign public health officials on the condition they [i]never[/i] make use of DDT.

According to Dr. Donald Roberts, professor in the Department of Preventiive Medicine/Biometrics at the Uniformed Services University of the Health Sciences in  the July 22, 2000 issue of the Lancet, "Claims of risks of DDT to human health and the environment have not been confirmed by replicated scientific inquiry."

Time for my two cents:

The main reasons the WTC came down have all been alluded to in the above threads, but a detail has been missed.

It is true that the WTC used a structure that was extremely efficient and utilized the outside walls to hold the building up. However, the strutted panels over which the concrete floors were poured did more than just hold up their respective floor. [b]They also kept the outside walls from buckling under the weight of the building.[/b]

Imagine the tube from a roll of paper towels. You may be able to put a paperback novel on top of it, but not a volume from an encyclopedia. However, if you glue little bits of cardboard throughout the interior of the tube, it makes the outside walls stiffer, and thus able to hold added weight.

What happened at the WTC is that the impact of the jets and the heat from the fires caused the floor spans to melt or collapse, thus weakening the support supplied to the outside walls. When a sufficient number of spans failed, the outside columns were left without their stiffeners, and they buckled under the weight of the building above them. Once the first floor started moving, there was no stopping the process.

In the case of the North tower (pictured above), the top 10 floors or so came straight down in a classic pancake fashion. Note that the impact of the aircraft had not damaged the corners of the tower, where the structure is strongest.

On the South Tower, the impact took out one side of the building and at least one corner. That tower did not, at first, come straight down. It actually broke in half at the impact point and started to topple over [b]sideways[/b]. Luckily (as if there was any such thing that day), the weight of the toppling upper section caused the lower section to pancake, bringing both sections straight down.

Jet fuel can burn for an extremely long time, especially if it is kept at high temperature in a confined space without sufficient oxygen. The flames will stop, and as soon as more oxygen is introduced, WOOOSH! A reflash.

The reason the Empire State Building didn't come down is that the impact was smaller, the fuel load was far less, and the fact that the building is constructed almost entirely out of heavy I-beams. No finesse, just rock-solid engineering.

That being said, there is no guarantee that the Empire State Building would survive a 9/11 style attack, especially if more than one plane were used. One thing is certain, however, the building would likely last much longer than the WTC did.

I get furious at pinheads who state that the WTC was "inadequately built". The WTC was a masterpiece of engineering in every possible way (other than aesthetics, where it admittedly needed some help). It was extremely efficient and withstood an impact far greater than what it was originally designed for. The architects deserve to be [b]complimented[/b], not criticized.

To answer the question above, a moving body's kinetic energy varies directly with its mass and the [b]square[/b] of its velocity (KE= 0.5*M*V^2). Double the speed and you have [b]four[/b] times the energy.

The WTC was designed to survive an impact from a 707 lumbering slowly around while lost in fog. 9/11 saw aircraft that were far more massive than the 707, and they were flying [b]fast[/b].

The photo above turned my stomach. I grew up in NYC, and I regret that I never got to see the destruction for myself since no photograph or group of photographs will ever adequately capture the magnitude of the destruction that day.

On the other hand, maybe that's a blessing...

This entire post is junk science.

I am sorry that I wasn't here for this discussion...anybody want to find the melting point of iron or steel and then compare it to
the "heat" of building materials or flashpoint of jet fuel?......oh yeah and why did the "other buildings" collapse?  wtc4,5,6,