The Virginia-class attack submarines are allocated to replace the ageing Los Angeles class of submarines which have housed a substantial portion of America’s mobile, nuclear arsenal. They are designed for extremely long-mission durations with minimal time spent in port for replenishment and 15-year maintenance cycles in dry dock.

In every sense of the phrase, they are designed as mission critical platforms for America’s defense.

The Virginia-class were chosen as the next generation of US Navy attack submarines after a lengthy consultation period and narrowly won the procurement process over the more expensive Seawolf class. Cost savings of an average $200 million are envisaged with the Virginia-class bill-per-submarine coming in at $1.8 billion (in Fiscal Year 2004). The actual build cost is now thought to be around $2.5 billion per boat though cost-saving measures are in force to secure pricing for the US Navy.

The cost-saving measures have focused on the concept of “Tango Bravo”, or Technology Barriers, which have presented themselves as the Block III vessels have moved from drawing board to shipbuilding yard. The complicated nature of the submarines combined with escalating costs and project management issues, and the political decision to place the construction orders with two contractors (GD Electric Boat and Northrop Grumman – the only two yards capable of building nuclear submarines in the US), have all placed considerable strain on cost control and meeting delivery schedules.

The importance of cost control in a budget constrained, economic environment is all too clear, however the strategic importance of delivering vessels to schedule is more important. The Los Angeles class is already one quarter the way through decommission and it was decided by Congress and the US Navy to accelerate delivery of the Block III submarines.

Part of the acceleration and cost-control measures implemented has involved taking existing technology and developments from other projects and redesigning them into the Block III Virginia-class boats. For instance, the bow design of the Block III boats is taken from the Ohio-class submarine fleet while jet-pumps have been utilised for decreased cavitation and for much quieter running even at higher speeds. The Virginia-class boats are reportedly quieter at 20 knots submerged speed than previous classes at 7 knots.

DARPA has overseen the Tango Bravo initiatives, which have also resulted in the adoption of externally stowed and deployed weapon systems (particularly torpedoes). Management systems also allow for control of the electromagnetic signature due to electrical and mechanical systems as well as the hull, all of which increase the stealth characteristics of the submarine. There is also increased automation of crew activities which reduce the workloads of the crew and increase operational efficiency.

At the heart of most of these Tango Bravo innovations lies the pumping systems which utilize a wide-range of pump models, including centrifugal pumps, screw pumps and highly engineered valves. These systems must be capable of operating with extremely long maintenance cycles in the most demanding operational environments conceivable. Many of the Tango Bravo systems cannot operate without highly advanced pump and valve systems to manage and operate them, from silent propulsion to weapon deployment.

Author Bio: Lawrence Reaves works with Colfax Corporation, a leading provider of industrial pumps such as crude oil transfer pumps and commercial marine pumps. Colfax Corporation can be found online at: ColfaxCorp.com or at their blog ColfaxCorp.com/blog .

Category: Education
Keywords: tango bravo, Virginia class submaries, Virginia class boats, industrial pumps