[El Gato]

I wonder how fast the notional 707 in the design requirements for the building was supposed to have been flying? I'll bet not anywhere near this fast, as they would not have been thinking about someone deliberately ramming the building at speed, but more like a plane off course upon landing or takeoff, when they would be going about 1/2 to 1/3 as fast. Since the energy involved in the collision is proportional to the square of the speed, and also to the mass/weight of the aircraft, one would think these strikes exceeded the design standard by a factor of 5 to 10, maybe more. The wonder is not that the buildings fell, but rather that they stood long enough for tens of thousands of people to get out before they fell.

[ml/nj]

I wonder how fast the notional 707 in the design requirements for the building was supposed to have been flying?

There is a 250 kts (288 mph) speed limit for planes flying below 10,000 feet. (Source: FARs § 91.117) Unless designers were expecting really illegal operation, they probably used 300 mph.

ML/NJ

[Excuse_My_Bellicosity]

By doing some quick hand calculations: a plane moving at 586 MPH has 5.5 times the kinetic energy of a plane moving at 250 MPH even though the speed of the faster plane is about 2.3 times the speed of the slower plane. (Kinetic Energy = 1/2 * Mass * Velocity^2)

[LarryLied]

Since the energy involved in the collision is proportional to the square of the speed, and also to the mass/weight of the aircraft, one would think these strikes exceeded the design standard by a factor of 5 to 10, maybe more. The wonder is not that the buildings fell, but rather that they stood long enough for tens of thousands of people to get out before they fell.

It is amazing. Even more considering the fuel. 757's carry 30 tons of fuel. As much energy as in 300 tons of TNT.

[sheik yerbouty]

I worked there for 8 years. The structure was quite strong, but the inner walls were junk.

[js1138]

I saw the TLC show on how the buildings collapsed. I don't think any engineer needs to feel guilty about the results of a military operation.

In retrospect, stairwells at the corners of the buildings would have saved most of the victims.