In the Ric Burns documentary "New York," Les Robertson says that they did design the towers to withstand the physical impact of one 707, but that they did not make any calculations about the effects of the jet fuel.
Another thing to bear in mind, of course, is building occupancy.
Between 1970 and 2000 average occupancy in city office buildings across the western world have tripled as more people are squeezed into tighter spaces.
Now, consider what else has changed.
Every one of those 3x as many people means 3x as many desks, 3x as many chairs, 3x as many pen holders...etc... think how much of that stuff these days is synthetic, made of hydrocarbon based materials. Compare that to 1970.
Another major thing of course, everyone now has a PC, and all the additional furniture that comes along with that.
Heat output, by floor area, has multiplied by 6 times since 1970 - where before a given space would have one person releasing body heat, now you have three people in the same given space, each with a PC (the average PC has roughly the same heat output as a single person).
That means more air conditioning units.
As you can see, failing to factor in the affect of fuel on the aircraft is only one error, and that one error alone has many ramifications. I recall one of those involved in the building describing the impact of a 707 as like a pen pushed through a mosquito net. This implies they didn't think the wings would penetrate the building.
It may just be the extra mass provided by the jet fuel, but to me such an assertation seems ludicrous (as materially demonstrated on 9/11) and supports how limited any real analysis of such an impact was.
Another error in the "calculated impact" of a 707 is, as I mentioned above, the massive difference in available fuels in the building itself from 1970 to 2000.
A modern office building is a veritible fuel tank of hydrocarbon based materials. Everything is plastic or nylon.
Another error is in fire proofing. At the time WTC was built there was NO guideline for how much fire proofing to put on steel.
NIST concludes that ultimately the fires in the building weakened the steel, causing collapse.
The CT 707 claim argues this wouldn't happen. Yet lack of minimum standards for fire proofing in 1970 indicates, to me, that no one had even seriously looked at the threat of steel weakening from fire.
As the
Kader Industrial toy factory fire (May 10, 1993) shows, unprotected steel structural buildings will suffer total collapse. In the example of Kader a small localised fire was discovered at 4pm in Building One (4 floors). It was not until 4.20pm that the fire was considered a significant enough threat to call the fire brigade. When they arrived at 4.40pm:
Arriving fire-fighters found Building One heavily involved in flames and already beginning to collapse, with people jumping from the third and fourth floors.
Sound familiar?
The building suffered total collapse at about 5.15pm.
The fire then spread to Building Two (4 floors) which suffered total collapse at about 5.30pm (15 minutes later), and Building Three (4 floors) which in turn totally collapsed at 6.05pm (35 minutes after Bldg 2).
The later investigation found that none of the steel in the structures was insulated against fire. Thus we can see just how important insulation is in a fire scenario.
It would be likely that those sections of steel in the WTC that were stripped of insulation in the impact were experiencing total structural failure within 20 minutes.
-Andrew
Man, they are really out of arguments!
)