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SSN-688 Los Angeles-class Upgrades

SSN 688-class submarines, which will comprise 68% of the attack submarine force in 2015, must be modernized to ensure that they remain effective against increasingly sophisticated undersea adversaries. The use of COTS and open systems architecture (OSA) will enable rapid (annual) updates to both software and hardware, and the use of COTS-based processors means that sonar system computing power can grow at the same rate as commercial technology.

The creation of the Acoustic Rapid COTS Insertion (A-RCI) program was based on a detailed review of the U.S. acoustic advantage compared to foreign nuclear and diesel electric submarines. This program is the centerpiece of the Los Angeles (SSN 688)-class modernization effort. It also will provide the submarine force with a common sonar system. The process is designed to minimize the impact of fire-control and sonar system upgrades on a ship's operational schedule, and will be accomplished without the need for major shipyard availabilities.

A single A-RCI Multi-Purpose Processor (MPP) has twice as much computing power as today's entire submarine fleet (SSN-688/688I/21/726 class) combined. It allows development and use of complex algorithms that were previously well beyond the capability of legacy processors. The use of COTS/OSA technologies and systems will enable frequent periodic updates to both software and hardware with little or no impact on submarine scheduling. COTS-based processors allow computer power growth at nearly the same rate as commercial industry.

A key facet of the sonar A-RCI program (now designated AN/BQQ-10) includes the Submarine Precision Underwater Mapping and Navigation (PUMA) upgrade. This consists of software processing improvements delivered as part of Advanced Processor Build (APB) 02, to the AN/BQQ-10 High Frequency (HF, A-RCI Phase IV) and AN/BQS-15 EC-19 (SSN-688 only) sonar systems. This enhancement provides submarines with the capability to map the ocean floor and register geographic features, including mine-like detections, and display the map in a 3-D representation. This capability to precisely map the ocean floor allows submarines to conduct covert battlespace preparation of the sea bottom as well as minefield surveillance and avoidance, with impunity. These digital maps can be compressed and transmitted to other naval forces for display on sea-borne and land-based platforms.

Phase I, which commenced in November 1997, enhance towed-array processing. A-RCI Phase II (FY 1999) provided substantial towed and hull array software and hardware processing upgrades that significantly improved LF detection capability. Phase III (FY 2001) augments the current Spherical Array DIMUS beamformer with a linear beamformer and enhanced processing that improves MF detection capability. Phase IV (FY 2001) upgrades the HF sonar on late-generation, Improved Los Angeles-class submarines (SSN-688I). Each phase installs improved processing and workstations (point click trackballs, Windows environment). Recent, real-world encounters have consistently demonstrated overwhelming success of this program to restore U.S. acoustic superiority. The BQQ-10 sonar system is being installed as rapidly as possible given the available funding.

Additional funding will accelerate vital improvements to towed array processing in support of fleet operations, accelerated delivery of organic mine countermeasures (MCM) capability inherent in A-RCI Phase IV and PUMA, and completing Phase III upgrades for all submarines.

Navy research, development, test, and evaluation will continue to develop processing algorithms from the surveillance, tactical and advanced RD communities, perform laboratory and at-sea testing, and distribute upgrades periodically. Congressional support for additional MPP development has allowed the Navy to leverage the Submarine Force's leading edge developments across a broader range of anti-submarine warfare and undersea surveillance systems through the Navy Common Acoustic Processor (NCAP) program. Development of PUMA remains on schedule and completed late in 2001. Backfit of this capability began in FY 2002 and will be complete on all Los Angeles-class submarines in FY 2006.

In February 2005 Digital System Resources Inc., Fairfax, Va., was awarded a $44,559,458 cost-plus incentive-fee/award-fee modification to previously awarded contract (N00024-04-C-6205) for FY05 level-of-effort engineering and technical services in support of the Multi-Purpose Processor (MPP) program. The MPP is a combination of hardware and software that enables submarines to process data collected by towed and hull arrays. It is installed on SSN 688, SSN 688I, SSN 774, SSN 21, SSGN and SSBN 726 Class. The processed data provides valuable information regarding the location of other nearby vessels and, thereby, increases survivability and lethality of the submarine. The contract will provide for services and associated materials for the design and development of upgrades, systems support and production of the system, which is a major subsystem under the Acoustic Rapid Commercial Off-The-Shelf Insertion (ARCI) program.

The TB-29A submarine thin-line towed array is a COTS version of the legacy TB-29 towed array. These arrays will be used for back-fit on Los Angeles (SSN-688 and SSN-688I) and Seawolf (SSN-21) submarines and forward-fit on the Virginia (SSN-774) class. TB-29A will also be used for the SURTASS Twin-line towed array system. It will provide greater capability than the current TB-23 Thin Line towed arrays and achieve enhanced supportability through commonality. TB-29A uses COTS telemetry to significantly reduce unit cost while maintaining superior array performance. These arrays were tested with SURTASS ships and supported the IUSS community starting in FY 2004. Coupled with the submarine A-RCI system, TB-29A arrays provide the same 400-500 percent increase in detection capability against quiet submerged platforms in blue-water and shallow-water areas, as the current TB-29 has demonstrated.

The AN/BLQ-10 system will be the advanced signals intelligence (SIGINT) system for the Los Angeles (SSN-688), Seawolf (SSN-21), and Virginia (SSN-774) classes. It will support operations in both the open ocean and the complex littoral signals environment. The system consists of signal sensors, receivers, displays, advanced processing, and analysis equipment. SIGINT provides detection, identification (including specific emitter identification capability), analysis, and direction-finding for radar and communication signals emanating from ships, aircraft, submarines, and other emitters. SIGINT equipment is used by attack submarines to aid in self-protection, situational awareness, and, when augmented with special carry-on SIGINT equipment, intelligence gathering.

The AN/BLQ-10 SIGINT System entered development in October 1994. The Engineering Development Model completed an operational deployment on board the USS Annapolis (SSN-760) in 2000. The first backfit production shipset was installed on USS Tucson (SSN 770) in 2001.

Changes to mission objectives require that SSN 688 Class submarines be capable of sustained operation in areas where seawater temperatures are significantly warmer than original system design requirements. The SSN 688 Class submarines R-114 air conditioning plants are seawater cooled and were originally designed for operation with a maximum seawater temperature of 85 F. Operation in warmer seawater increases the condensing temperature, resulting in greater condensing pressure and decreased cooling capacity. The air conditioning plant cooling capacity in higher temperature seawater (as high as 97 F) is significantly less than the 150-ton cooling capacity at 85 F seawater temperature. Maintaining capacity under the higher seawater inlet conditions requires increased power (larger motor) and higher impeller rotational speed.

NAVSEA PMS 392 leveraged NSWC Philadelphia's experience on surface ship CFC-Free air conditioning plant conversions to help execute an aggressive design, qualification testing, and installation program to improve the R-114 air conditioning plant performance on SSN 688 submarines. NAVSEA's goal was to have the first upgraded unit installed on an SSN 688 Class submarine during FY 06. To reduce installation costs, the design will be hatchable, requiring all components to pass through a submarine hatch of 30 inches in diameter.

An extensive evaluation was performed to assess the material condition and previous performance of a SSN 688 R-114 air conditioning plant located at the Division's Philadelphia site, which served as the test platform for the warm water modifications. The subject SSN 688 Class air conditioning plant was purchased by the Division's Annapolis site in 1992 under the CFC Elimination Program. The unit was installed at Annapolis, and baseline performance testing begun. Shortly thereafter CNO decided to "vintage" submarine R-114 air conditioning plants and not convert these units to R-236fa. The development effort on the SSN 688 air conditioning plant was terminated. The SSN 688 unit remained idle at Annapolis until the fall of 2000. The unit was preserved and then transferred to Philadelphia where it remained in storage until Spring 2003.

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Page last modified: 07-07-2011 12:55:09 ZULU