Speed of design of airplanes.

As opposed to when?

It was comparatively easy to design an aircraft in say 1937. All you
had to do was bend some metal, rivet on some aluminium, and send a
brave man up to fly it. If he didn't come back, you went on to another
design. If he did, you could improve it according to his notes. This
is not a valid approach with supersonic aircraft.

But your point is valid. The Word Trade Center was collapsed more than
two years ago, and they're still arguing about the design of its
replacement. Does anybody seriously expect to enter that building on
the 5th anniversay of 9/11? By contrast, the Empire State Building
went from first turn of the shovel to first public occupancy in about
one year.
all the best -- Dan Ford
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