Summary: The Navy is developing a new destroyer, the DD(X), to serve as a next-generation multimission surface combatant ship. It will provide advanced land attack capability to support forces ashore and contribute to military dominance in shallow coastal water environments. To reduce program risk and demonstrate the ship's 12 technologies, the Navy is building 10 engineering development models that represent the ship's most critical subsystems. This approach is intended to improve the assessment of these key subsystems by designing, developing, and testing working models early in the process. In September 2004, we reported that while the engineering development model process could be beneficial, the program's schedule does not allow enough time to acquire appropriate levels of knowledge before key decisions are made. We also reported that some of the engineering development models were progressing according to plan, but others faced significant technical challenges. This letter provides an update on the progress of DD(X) subsystems, as demonstrated by recent tests and design reviews of the engineering development models. Our review concentrated on five of the ten engineering development models. These five development models were chosen because of their importance to the overall ship design, congressional interest in specific models, or the occurrence of recent test events. We provide more limited information on the remaining five development models.
The DD(X) program's demonstrations and component tests met the exit criteria for its engineering development models established by the Undersecretary's August 2004 memorandum. While progress has been made, the level of technology maturity demonstrated remains below what is recommended by best practices, as outlined in our September 2004 report. Tests of several engineering development models resulted in successful demonstration of exit criteria. In other cases, tests 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. 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. The multifunction radar, a segment of the dual band radar, successfully completed the land-based testing described in the exit criteria, but the volume search radar has encountered technical problems with a key component. The integrated deckhouse and apertures development model will soon begin testing for antenna placement and radar cross section. Questions about the properties of the proposed component materials are delaying production of an article for fire and shock testing. The advanced gun system demonstrated exit criteria through modeling, and additional component tests have verified this performance. An early failure in required munitions flight testing was overcome, and two further flight tests have been completed successfully. Tests of the peripheral vertical launch system led to a redesign effort; tests to determine the suitability of the new design will complete in June 2005. Weight is a challenge for individual subsystems and the ship as a whole. 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.
