"Kingfish" wrote in message
ups.com...
I'm somewhat surprised to see Airbus having such difficulties
considering the A380's having been designed on a computer (3D digital
mock up). I thought the main benefit of CAD was to have the ability to
test for systems integration before any metal is cut(?) Of course this
is an extremely complex aircraft with many complicated systems that
must all play together, and the latest wiring harness issue may not be
related to any design deficiency.
By comparison, I recall seeing a documentary on the 747's service entry
(1970) that had its share of gremlins. (IIRC a big source of headaches
were the Pratt JT9D fans) The documentary didn't go into much detail
about the program's problems, (I'm sure there were a few) but that
airplane was designed by engineers on drafting tables and not
computers. I just assumed new aircraft designs would have smoother &
shorter development because of modern computing power.

As someone who is involved in the design of industrial equipment and
facilities, I submit that "computerization" - i.e. CADD and other time
saving tools have made it so easy to make design changes that designs are
seemingly *never* frozen. This means that all of the involved parties don't
get the opportunity to make sure their pieces actually fit the product at
its frozen stage. Beyond that, airplanes have closer tolerances and less
margin to move things around than many other items, meaning that making "my"
new assembly fit "your" new component can be extremely difficult. And may
involve the modification of several other components or systems via the
ripple effect.

On top of those issues, the complexity of aircraft systems has increased
several fold over the years. Integrating those systems is a far bigger task
than building a flyable airframe.