In article ,
says...

The other difference is that while NASA was able to greatly reduce
weight after Enterprise prototype, this doesn't happen anymore because
the modern design software already optimizes structures and generally,
some parts need to be beefed up after prototype is built. (aka: 787
ended up significantly heavier than originally predicted by Boieing,
same with the A380 from Airbus).


Untrue. It certainly does still happen.

Agreed. You don't know your final aircraft/launcher/spaceship mass
until it's completely designed and done with test flights. The best
software in the world doesn't have a freaking clue what your
constratints, loads, and etc. are. Some of those you won't know exactly
until after your test flights.

That's why the structure of both Enterprise and Columbia was heavier
than the other orbiters. The engineers weren't certain what the flight
loads would be, so they were conservative in their estimates. In the
end, they were a bit too conservative so subsequent orbiters were
designed and built with lighter structures.


It was originally
intended to rebuild it to 'space standard' after the tests were over,
but that just proved to be much more expensive than they'd
anticipated. The same thing could wind up being true of the first
Block of BFR Spaceship.


With Modern design techniques, Enterprise would have been built
pre-optimized.


Horse****. They didn't design the thing using bearskins and stone
axes, you know.

Agreed. Some of the first finite element analysis software came out of
NASA. Its roots date back to the early 1960s. It eventually led to the
commercial FEA software known as MSC Nastran.

https://en.wikipedia.org/wiki/Nastran

Due to a finding that they were a monopoly in the US, my company
obtained a copy of the source code and we hired several NASTRAN
developers, so today you can buy Siemens NX Nastran:

https://en.wikipedia.org/wiki/Nastran#NX_Nastran

https://www.plm.automation.siemens.c...enter/nastran/

Jeff
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