US Navy ends development of DART sonar with Raytheon

WASHINGTON — The United States Navy will end its work with Raytheon Technologies developing sonar for littoral combat ships and frigates and will instead purchase sonar already in use by several navies around the world.

Raytheon’s AN/SQS-62 variable-depth sonar, also known as a dual-mode array transmitter, was a key component of the LCS anti-submarine warfare mission suite and was to be incorporated into the Constellation-class frigate program to create commonalities within the superficial force.

But the sonar, while successfully tracking a submarine in test runs, still had two remaining technical challenges: the hydrodynamic stability of the system trailing behind the ship, and the performance and reliability of the transducers.

Defense News previously reported that the program office halted testing in September after realizing hydrodynamic issues would require an active control system.

The general manager of the unmanned and small fighter program Rear Adm. Casey Moton told Defense News on March 31 that around the same time, the Navy grew increasingly concerned about the risk this posed to sonar development and whether the product would be a viable option for future ASW. operations.

Coincidentally, the Navy was nearing a decision point with Fincantieri Marinette Marine on the final frigate design, as the ship’s critical design review and production readiness review approach.

“It really came down to our concern about the risk with the DART system…and the risk to the advancement of the frigate design, and ultimately further potentially if we go into production and have issues, impact production , a performance impact,” Moton said. in a telephone interview.

At the same time, the Navy was considering reducing the number of LCS hulls in the fleet as part of cost reduction measures in the fiscal year 2023 budget request. , reducing the number of hulls needed to carry out the other two missions: surface warfare and mine countermeasures.

“Due to the increased risks and challenges encountered with variable depth sonar,” the Navy released a solicited source in early February, Moton said.

After evaluating options, the service selected CAPTAS-4, or Combined Active Passive Towed Array Sonar. The product is manufactured by Advanced Acoustics Concepts, a joint venture between Leonardo DRS and Thales Defense & Security.

The Rear Admiral said CAPTAS-4 was chosen in part because of its proven performance in international navies and its high technical readiness, reducing the risk of integrating it into the underwater warfare combat system and Navy frigate hull design.

Moton said that when shipbuilders were vying for the contract to design and build frigates won by Fincantieri in 2020, they were allowed to choose between incorporating hull-mounted sonar or variable depth sonar towed behind. vessel.

While the shipbuilder could choose the style of sonar they wanted—with Fincantieri electing the VDS—the Navy reserved the right to dictate which system the builder would use. Raytheon’s DART was previously the Navy’s VDS of choice so it could realize the savings in production, training and sustainment costs associated with having common systems across multiple classes of ships, Moton said.

But, he said, the Navy had worked with Raytheon to design, model and ultimately test several enhancements to address lingering technical issues with DART.

“In these tests, we didn’t see the performance improvement that we had anticipated, and so it became clear that this was going to be more complex to fix than our first set of efforts,” he said. declared.

Moton said Fincantieri supported the decision to switch to a different sonar and helped review alternatives offered in responses to sources in February.

Moton declined to say how many companies offered sonar solutions, except to say that Raytheon’s DART was considered the incumbent and that “several other” products were being considered.

The Thales website indicates that the CAPTAS-4 is deployed on the French and Italian FREMMS – the Fincantieri frigate design which serves as the parent design for the Constellation-class FFGs – as well as the British Type 23 and Type 26 frigates, the Chilean Type 23 frigates and the Spanish F110 frigates.

Moton said the US Navy had some familiarity with the system from working alongside those allies in Europe, as well as using the associated Thales low-frequency airborne sonar as dipping sonar for MH-60 Sea Hawk helicopters.

He said the sources asked asked the companies to explain the technical maturity of the sonar, its performance and reliability in past sea operations, its integration on other classes of ships, its potential integration into the combat system SQQ-89 submarine warfare aircraft and how well its production schedule would match that of the Constellation line of frigates, among other issues.

Moton said Advanced Acoustics Concepts and Fincantieri are still expected to negotiate sonar pricing, but he doesn’t expect the change to significantly affect the cost of the program. Likewise, he said the Navy would need to do some integration work between the sonar and the combat system, but he didn’t expect that cost to be significantly different than expected.

Capt. Kevin Smith, frigate program manager, said on the call that with the new sonar selected to help reduce program risk, the frigate could soon move on to its critical design review and performance review. preparation for production. These milestones were previously scheduled to occur in the second and third quarters, respectively, of FY22.

“We are not going to start [production] unless we feel we have a mature design so we don’t relive some of the challenges we’ve had with building lead ships. I expect we will still have challenges as the lead ships are very difficult, but we are trying to mitigate that as much as possible with a mature design,” he said.

Megan Eckstein is a naval warfare reporter at Defense News. She has covered military news since 2009, with a focus on US Navy and Marine Corps operations, acquisition programs and budgets. She has reported on four geographic fleets and is happiest when recording stories from a ship. Megan is an alumnus of the University of Maryland.

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