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June 17, 2005

DD(X) has a weight problem

As well as getting more expensive, the DD(X) destroyer is also apparently getting heavier.

The GAO (Government Accountability Office) this week issued a report (GAO-05-752R) on "Progress of the DD(X) Destroyer Program."

To reduce program risk and demonstrate the ship's 12 technologies, the Navy is building 10 engineering development models that represent the shipÕs most critical subsystems. In September 2004, GAO reported that the program's schedule does not allow enough time to acquire appropriate levels of knowledge before key decisions are made. GAO also reported that some of the engineering development models were progressing according to plan, but others faced significant technical challenges. This week's report provides an update on the progress of DD(X) subsystems, as demonstrated by recent tests and design reviews of the engineering development models.

While progress has been made, says the report, "the level of technology maturity demonstrated remains below what is recommended by best practices, as outlined in our September 2004 report."

Some tests have identified "technical problems that will need to be overcome before ship installation or that have led to changes in the ship design."

"The permanent magnet motor, a key element of the integrated power system, failed tests, and was replaced by the advanced induction motor," says the report. "Because the Navy maintained the induction motor as a fallback technology, the integrated power system was able to meet the exit criteria. The substitution of the advanced induction motor does change the noise, weight, and space usage of the power system, which could have implications for the ship design."

"Weight is a challenge for individual subsystems and the ship as a whole," says the GAO. "The integrated power system, advanced gun system, and integrated deckhouse all have encountered problems staying within weight limits. These problems have contributed to overall weight growth in DD(X). As a result, the current design is slightly over the margin reserved for weight in the system development phase, which ends with critical design review in August.. A number of key events to demonstrate technology will occur near the end of this phase, and it remains to be seen whether they will have any impact on weight. Other elements of the design for certain subsystems, including space issues for the power system and materials issues on the deckhouse, remain unclear. These challenges could result in changes late in design or during construction, leading to higher costs."


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