Reply #125: One more point. [View All]

[longship]

The Pentagon *is* exceptionally hardened. It was built at a time of world war to be able to withstand attack. Also, it was to be a temporary military building which was to be used as a huge warehouse after the war. This is why it was way over-engineered.

Did you read my post with the energy calculation? I hope so.

Now, to the construction of an airliner:

An airliner is almost completely hollow inside. There are few big chunks of metal in it. Almost all of it is composed of thin aluminum alloy formed into long boxes which makes the airframe stiff yet flexible enough to stand the stresses of flight. The wing spar is not a solid piece, nor is the fuselage backbone (actually in the belly of the airframe). The entire top 3/5 of the fuselage is a hollow ribbed shell with a thin skin around it. You would be shocked to see how little metal is in the upper fuselage. The stabilizers are very light and essentially hollow.

Aluminum is stiff, but brittle. It has a low melting point. It bends easily. Airframes only work within the very narrow parameters of safe flight. Within a month of 9/11 an Airbus A-300 crashed into Queens, NY when a co-pilot accidently applied too much rudder to counter the turbulent vortex from the 747 that took off just before it. The whole vertical stabilizer sheered off just from over agressive application of the rudder pedals. The attachment points on the Airbus were titanium!!

Airframes are not meant to be man-handled. A crash of this violence results in the total destruction of the airframe. Anybody claiming otherwise is just plain stupid.