And the twin towers were designed to take an airliner hit yet these aluminum airliners punched right through. That was some tough aluminum. I followed John Lear on these attacks.
Ummm... the towers did indeed “take the hit” but apparently nobody adequately accounted for the weakening of the steel structure from the ensuing fire which caused the floors to pancake and the entire structure to telescope downward in a cascade failure.
My opinion (take it for what it’s worth) is that the failure-mode of the buildings were not adequately considered. And even if they did consider the possibility of an airplane strike followed by a fire... airplanes were scaled-up in size and range (fuel capacity) since 1966 when construction began.
I’m reminded of the crash test film of a nuclear reactor containment structure where an F-4 Phantom strapped to a rocket sled was ‘launched’ at the structure in an attempt to simulate a Boeing 707 hit. This was used to certify the design. A Boeing 707 is puny compared to today’s jumbo wide-bodies, meaning that every nuclear containment vessel’s ability to sustain a hit is open to question.
Ho building will not be punched by a full-speed airliner. It’s the same as a tornado thrusting a straw through a telephone pole. It’s all about the kinetic speed vs a stationary object.