Navy sub is virtual-for now

Electric Boat Corp. won't build the NSSN until next year, but it's already swimming in
uncharted waters. The entire sub has been built virtually through computer-aided design,
making it the undersea answer to the Boeing Corp.'s CAD-developed 777 airplane. The 777
was the first commercial aircraft totally developed using CAD, but a modern,
nuclear-powered attack submarine is much more complex.


As the replacement for the Navy's Los Angeles-class attack submarines, the NSSN
incorporates much of the advanced technologies of the Seawolf-class submarines but with
next-generation underwater stealth. And, as Navy officials demanded, the $1.5-billion NSSN
will be smaller and less expensive than the Seawolf but more advanced than the Los
Angeles.


With a crew of 150, the 7,700-ton sub will be able to travel faster than 25 knots,
unaccompanied and unnoticed, to potential trouble spots in any of the world's oceans for a
broad range of missions. Over its 30-year life, the NSSN will for months at a time remain
submerged at depths in excess of 800 feet.


Electric Boat designers and engineers since 1993 have designed the Navy's NSSN using
3-D electronic mockups. This technique enables the company to seamlessly transition from
computer screen to production without physical prototypes. By developing the sub onscreen
instead of on paper, Electric Boat has been able to run full-scale simulations and to
correct conflicting designs without ever building a mockup. Gone, possibly forever, are
the days when full-scale wooden mockups of subs were used to review a design.


Digital mockups let the designers and engineers concurrently design, develop, check and
integrate all parts, eliminating the traditional separation between design and
manufacturing. Electric Boat's software-a computer-aided, three-dimensional interactive
applications (CATIA), Solutions Version 4 developed by France's Dassault Systemes and
marketed by IBM Corp.-converts each part of the sub into a 3-D mockup.


Electric Boat officials said the company's investment of more than $100 million is
paying off. CATIA has reduced the NSSN's design and build time by two years each, saving
millions of dollars.


To develop the sub, Electric Boat linked IBM RS/6000 and Silicon Graphics Inc.
workstations and clustered mainframes. More than 950 CATIA seats are used concurrently on
the mainframes and Unix workstations. This configuration lets more than 1,000 designers
and engineers divided into 15 major teams simultaneously work on different parts of the
sub.


Electric Boat's Groton shipyard also is linked to its pre-assembly plant in Quonset
Point, R.I., where digital schematics are sent to refine the design. The Navy's NSSN
program office in Arlington, Va., is brought into the design process on a weekly basis
through teleconferencing. The sub's first hull segment is already under construction.


The NSSN's computerized design, which requires 150G of disk space, lets designers
create a virtual sub from more than 50,000 drawings with the Interactive Graphic Robotics
Instructional (IGRIP) software package. IGRIP color-codes the sub's individual systems and
components to warn of potential design conflicts.


In tandem with IGRIP, Electric Boat also has built five electronic visualization
systems that let developers walk electronically through the sub via computer displays that
project onto 9- by 12-foot screens. These require 8G of RAM.


Along with three-dimensional digital product modeling, a construction database is
revolutionizing the way subs are built. To keep track of the 1.1 million parts and 100,000
separate activities needed to build NSSN, Electric Boat enlisted the support of Artemis, a
computer program for planning complex tasks developed by France's Metier Management
Systems and now owned by Computer Sciences Corp.


Electric Boat officials say they hope the sub's computer-based design will mean a
smoother production process.


NSSN's modular design and construction will reduce costs and let mission-specific hull
sections be incorporated into future construction. Individual modules now can be tested
before installation into the hull as well, preventing costly replacements or changes later
in construction.


NSSN's digital design and modular construction will let Electric Boat customize the sub
to meet the Navy's future requirements. The open system architecture and commercial
electronics gave the builders flexibility to insert newly available technologies as
needed.


Congress has approved funding for the NSSN's design but not its construction. The Navy
has requested $2.6 billion in fiscal 1998 for the continuing design and construction of
the first NSSN. The service plans to buy four NSSNs by 2002.


The Navy wants to christen the first NSSN in 2004.


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