The Navy should consider outfitting the next-generation DD(X) destroyer with a permanent magnet motor for the ship's integrated electric-drive propulsion system “as soon as possible” to reap energy efficiency and operating benefits, Rep. Roscoe Bartlett (R-MD) told Inside the Pentagon April 7.

The House Armed Services projection forces subcommittee chairman said he believes service officials were “stuck” after opting instead to use advanced induction motor, or AIM, technology for the future warship.

The Navy wants DD(X) to be a multimission ship with an emphasis on naval surface fire support. Last week, the service designated the first ship of the class, the Zumwalt, as DDG-1000. The vessel is scheduled for delivery in 2012.

The new destroyers, with a crew size of 125 to 175 sailors each, will incorporate several new surface combatant technologies. Each one will be equipped with two 155 millimeter Advanced Gun Systems and 80 missile tubes for Tomahawk cruise missiles.

The ships also will have new electric-drive propulsion systems. Embracing electric-drive technology gave designers unprecedented flexibility in developing the new warships since they were no longer faced with as many limitations related to building around a central drive shaft.

For years, advocates for electric drive also touted the benefits of being able to switch power from propulsion to other systems as deemed necessary by ship captains.

An integrated electric-drive propulsion system will conserve energy for DD(X) and make it possible to employ various high-power weapon systems, reduce crew size and maneuver faster, Navy officials say.

“Compared to a traditional mechanical-drive propulsion system with two separate sets of turbines -- one for propulsion, the other for generating electricity for shipboard use -- an integrated electric-drive propulsion system can reduce a ship's fuel use by permitting the ship's single combined set of turbines to be run more often at the most fuel-efficient speeds,” Ronald O'Rourke, a Congressional Research Service national security expert, told Bartlett's committee during an April 6 hearing.

In the past, the Navy looked at both PMM and AIM as candidates for the DD(X) class.

AIM technology is considered more technologically proven, but the motor is heavier and requires more space than a PMM. AIM also requires a “separate controller” to be developed to meet noise requirements and produces “one-third the amount of voltage” produced by PMM, states a May 2005 Navy-Northrop Grumman DD(X) analysis cited by Bartlett in his opening statement from last week's hearing.

Bartlett is an advocate of PMM technology because “the smaller total power plant” would yield more energy for a number of missions, he told ITP.

Nonetheless, PMM has been deemed too risky by Navy officials.

The first “propulsion-sized PMM experienced failures with its stator insulation system during factory testing in January 2005,” reads a statement submitted jointly for the hearing by Surface Warfare Director Rear Adm. Bernard McCullough, Chief of Naval Research Rear Adm. William Landay, Undersea Technology Director Rear Adm. Stephen Johnson and Naval Sea Systems Command Ship Design Deputy Commander Rear Adm. Kevin McCoy.

Officials told lawmakers that a “root cause failure” analysis showed the manufacturer was not fully aware of the “implications” of scaling PMM to a more powerful motor. The convergence of the failed test with an upcoming milestone prompted the service to choose the more reliable, although less advanced, AIM technology for the DD(X) lead ship, the officials said.

“The baseline for the DD(X) lead ship was shifted to the fallback AIM system in February 2005 in order to support ship critical design review,” the joint statement reads. “In order to proceed with detail design and construction of DD(X) lead [ships], the program had to complete land-based testing of two critical test parameters prior to the conclusion of the ship [critical design review] as directed by Congress in the fiscal year [2005] Defense Appropriations Act conference report.”

An attempt at retesting PMM would have taken two months and cost the Navy $15 million, Landay said at the hearing.

The stator insulation system malfunction during the test was fixed two months after the event, Patricia Williamson, vice president of corporate communications and investor relations at DRS Technologies, told ITP April 12.

The Navy's decision in February not to ship the PMM for testing based on the “relatively minor problem” was “extremely surprising and disappointing,” she added. DRS had been developing the PMM under a $100 million contract with the Navy.

“We still think our solution is the better one,” Williamson said, adding that the “electrification” of Navy ships “will occur in the future” and that more energy will be needed not only for propulsion but for advanced weapon systems.

DRS does not expect a decision to take place on whether PMM will be employed on future DD(X) ships “in the near future,” she said. The company's PMM model is complete and has undergone “internal testing” and if tapped for use on DD(X) would need to be tested for two more years, she added.

The AIM device for DD(X) is made by Alstom, which makes electric-drive motors for cruise ships.

Last year, lawmakers on Capitol Hill proposed cutting funds for DD(X), which some critics say is too expensive. House authorizers took action by providing only $700 million in research and development funds and no ship construction money. They also demanded a $1.7 billion cost cap per ship, a move Navy officials said would terminate the program.

In late 2005, though, House and Senate appropriators agreed to fully fund the DD(X) program, including $716 million in advance procurement and $1.1 billion in research and development.

Further, in an acquisition decision memorandum signed in November, Pentagon acquisition executive Kenneth Krieg approved milestone B for the program, kicking off the ship's system development and demonstration phase. Northrop Grumman and General Dynamics are leading separate teams that are concurrently building a lead ship.

At the hearing, Landay told lawmakers trying to use PMM devices in the DD(X) lead ships would be a “huge technology leap.”

“While the technology remains an option for insertion in future hulls, PMM represents too much risk for the DD(X) lead ships,” the Navy statement reads. “While the PMM was not developed in sufficient time to support DD(X) lead [ships], the Navy continues to consider it and other innovative propulsion systems candidates for future DD(X) ships and other ship classes once it passes the same rigorous land-based testing program that AIM completed.”

Congressional appropriators should “work with” the Navy to try to increase testing on PMM technology because officials are “stuck out there on a limb” without technology they originally deemed worthy in 1999 at the onset of the program, Bartlett told ITP.

Bartlett believes transitioning many of the Navy's vessels to technologies that reduce energy use will fortify the fleet against oil shortages in the future.