SSN-774 Virginia-class Spiral Development
The VIRGINIA Class submarine program has been designed with long-term technological innovation in mind. The built-in flexibility of VIRGINIA, including incorporation of modular design techniques, open architecture, and COTS components, allows for technological insertion and innovation.
Open system architecture and modular designs will allow greater capability and easier upgrades at the component and system level. Payload modules will be used in the sail of the submarine to allow rapid change out of mission specific masts and installation of non-mast sail payloads. Bow and amidships payload sections will allow for larger volume modules that may support deployment of special forces, conducting expanded strike missions, or additional specialized sensors including UUVs. These modular concepts will allow greater mission flexibility. Additionally, modular hull design and construction will also enable greater adaptability, such that future ships may be modified to support new capabilities and configurations at lower cost, with less effort, and in less time.
The VIRGINIA Class program is using the Integrated Product and Process Design approach for design and construction resulting in a far more mature submarine design than has previously been achieved by start of construction. This accomplishment has greatly reduced the risk of design changes during construction - traditionally a major cause of cost increase.
With modular construction the Navy will be able to deploy significant payload variations in submarines using a single basic design. The modular architecture approach implements a basic, standardized structural "shell" that contains the nuclear propulsion plant and ship control functions along with fundamental self-defense capabilities. The VLS and torpedo tubes add their own flexibility. The VLS will permit future installation of a navalized version of the 160-mile range Army Tactical Missile System (ATACMS) or similar weapons, when they are eventually acquired. The torpedo tubes will support launch and recovery of Unmanned Underwater Vehicles (UUVs), such as the Long-Term Mine Reconnaissance System (LMRS), scheduleded to enter service in 2003 (one year prior to Virginia) or the deployment of Unmanned Aerial Vehicles (UAVs), if tube-launched versions are developed.
Each ship will improve on the capabilities of its predecessor and continue to improve total ownership costs. The Navy will continue to upgrade the Virginia Class capabilities with the evolutionary technologies being developed for the entire submarine force. In addition to this steady stream of incremental improvements, the Virginia Class SSNs will also introduce significant technological upgrades in a series of synergistic "bundles" at appropriate points in the program that will provide sharp gains in operational capabilities. The makeup of each of these upgrades will be based on several factors including priority of fleet needs, technical maturity and smart use of available resources.
The first of these major technology "bundle" insertions was targeted for a ship authorized around the 2006 time frame. Key payload enablers will be the Advanced Sail modularity opportunities and a new front-end design achievable as a result of introducing the Bow Conformal Array.
Conformal sonar arrays seek to provide an optimally sensor coated submarine with improved stealthat a lower total ownership cost. New technology called Conformal Acoustic Velocity Sonar (CAVES) will replace existing Wide Aperture Array technology and will be implemented starting in early units of the VIRGINIA Class. This technology will be expanded to allow conformal sonar arrays on other parts of the ship that will create new opportunities for use of bow and sail structure volumes while improving sonar sensor performance.
A second technology "bundle" was initially slated to be introduced around the 2010 timeframe. The unit to receive this "bundle" would have received technological improvements in accordance with ongoing plans of record as well as appropriate technologies identified by the DARPA Payload Study that have matured plus additional quality of life improvements. The focus of this second "bundle" was initially expected to be on the introduction of an electric drive system, in the Virginia Class. The introduction of electric drive technology will be the first step in the ultimate goal of achieving an all-electric submarine and the second step in achieving a truly flexible, modular submarine.
The Bundle spiral upgrade later gave way to Batches, and Blocks. Batches represented major design changes, while Blocks were multi-year procurement contracts. Not all technology insertions were timed to coincide with Blocks or Batches. The first two Blocks were Batch 1.
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