The world’s oceans are vast and deep, and submarines have been a vital component of naval forces for decades. These underwater vessels can operate silently, dive to great depths, and strike from unexpected directions, making them an incredibly effective tool in modern warfare. However, the ability of submarines to remain undetected is crucial, and this requires the use of advanced materials and technologies to enhance their capabilities.
A nuclear submarine is a ship powered by atomic energy that travels primarily under-water, but also on the surface of the ocean. Previously, conventional submarines used diesel engines that required air for moving on the surface of the water, and battery-powered electric motors for moving beneath it. The limited lifetime of electric batteries meant that even the most advanced conventional submarine could only remained submerged for a few days at slow speed, and only a few hours at top speed. On the other hand, nuclear submarines can remain under-water for several months. This ability, combined with advanced weapons technology, makes nuclear submarines one of the most useful warships ever built.
Submarines provide unique warfighting capabilities including a stealthy platform with great range, mobility, endurance, payload potential, and survivability. In many hostile environments, the submarine may be the only survivable platform. Future submarines will offer a significant degree of flexibility and reconfigurability, both internally and through the use of off-board vehicles, sensors, and weapons; they also will accommodate rapidly emerging technology to improve current capabilities and to enable new roles and missions.
Advanced battle management systems that enable cooperative engagement with other naval forces will enhance the effectiveness of submarine participation in complex missions including antisubmarine warfare, strike operations, theater and national missile defense, and the deployment of ground forces for specialized warfare. The greater relative survivability (based on stealth, mobility, and endurance) of the submarine and the potential for expanding the range and depth of mission effectiveness suggest a greater role for submarines in the Navy of 2035
One of the technology focus areas is Submarine Architecture, including hull structure, shaping, and materials. It encompasses the use of innovative design, materials selection, and total systems integration to significantly improve submarine performance, payload capacity, and stealth while improving manufacturability and reducing costs. The goals of advances in architecture include greater speed for the same power input by reducing drag, greater stealth through the reduction of acoustic and nonacoustic signatures, and simplified fabrication using creative structural design and advanced materials.
An integrated approach is required because changes to individual architectural components affect hydrodynamic and operational performance. Various geometries and materials have been identified that could provide improvements in hydrodynamic performance and reduced target strength and, in the long term, provide space and surface area for embedded sensors. Improved sail shaping could reduce life-cycle cost by facilitating maintenance.
The main material used in manufacturing a nuclear submarine is steel. Steel is used to make the inner hull that contains the crew and all the inner workings of the submarine, and the outer hull. Between the two hulls are the ballast tanks, which take in water to make the submarine sink and eject water to make the submarine rise.
All small modern submarines and submersibles, as well as the oldest ones, have a single hull. However, for large submarines, the approaches have separated. All Soviet heavy submarines are built with a double hull structure, but American submarines usually are single-hulled. They still have light hull sections in bow and stern, which house main ballast tanks and provide hydrodynamically optimized shape, but the main, usually cylindrical, hull section has only a single plating layer.
A double hull submarine has two major components, the light hull and the pressure hull. The light hull (casing in British usage) of a submarine is the outer non-watertight hull which provides a hydrodynamically efficient shape. The pressure hull is the inner hull of a submarine that maintains structural integrity with the difference between outside and inside pressure at depth.
The double hull approach also saves space inside the pressure hull, as the ring stiffeners and longitudinals can be located between the hulls. These measures help minimise the size of the pressure hull, which is much heavier than the light hull. Also, in case the submarine is damaged, the light hull takes some of the damage and does not compromise the vessel’s integrity, as long as the pressure hull is intact.
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