"nobody" wrote in message
...
Sylvia Else wrote:
There have been incidents where airliners have been stressed well
beyound their design limits to recover from extreme upsets, and the
passengers and crew have survived to fly another day,

"design limits" is the real keyword here. And it applies to bridges as
well as buildings.

The empire state building was built with tons of extra strength into it
because at the time, the knowledge of structural aspects of materials was
not
very good. So you end up with a big fat heavy building that is very
strong.
More recent buildings are built with much better knowledge of materials
and
thus are built with more exact strength, much lighter materials and much
thinner structure.

Similarly, modern aircraft are built with much better knowledge of
material
properties as well as aerodynamics. So the difference between the stated
limits and the actual physical limits are far less than planes built in
the
1960s. So breaking the "limits" today may in fact be far more dangerous
than
breaking the much less well known limits of the 1960s.

Johnson's flight demonstration of a early 707 being a prime example. Modern
day commercial A/C would never probably not survive, but if it did to the
scrap heap it would go.
Ralph Nesbitt
Professional FD/CFR/ARFF Type