SSN Seawolf Class Attack Submarine, USA

The Seawolf was conceived as a faster, better-armed eventual replacement for the Los Angeles class nuclear-powered attack submarines. The first of class, the Seawolf (SSN21), was ordered from the Electric Boat Division of General Dynamics, Connecticut, in January 1989 and commissioned in July 1997. Connecticut (SSN22) was commissioned in December 1998. The third, Jimmy Carter (SSN 23), is to be modified to improve payload carrying and underwater manoeuvrability. The alterations to the design will include modifications to the ballast control, mission management spaces and the creation of a flexible ocean interface known as a "wasp waist", which will enable the deployment and recovery of payloads without the use of torpedo tubes. Other additions include a new high capacity communications mast and ROV handling system. The Jimmy Carter was launched in June 2004 and commissioned in February 2005.

The Seawolf was a product of the Cold War, conceived to maintain the USA’s acoustic advantage over Soviet submarines. With the end of the Cold War and the change of emphasis to littoral operations, the cost of the Seawolf submarines was judged prohibitive and the programme was curtailed in favour of the smaller and cheaper Virginia Class New Attack submarines.

DESIGN

The Seawolf’s modular design introduces important improvements and innovations. It has greater manoeuvrability than the Los Angeles Class, space for later upgrades and weapons developments, and better sonars.

The Seawolf has a submerged displacement of 9,137t dived (12,139t for the Jimmy Carter), and 8,060t surfaced. Full acoustic cladding has been installed. It has a maximum speed of 35 knots dived, and a "silent" speed of 20 knots. It has a crew of 116 personnel, including 15 officers. With a diving depth of 610m, it has been designed with a sub-ice capability, with retractable bow planes.

COMBAT SYSTEM

The combat data system is a Lockheed Martin BSY-2 with a network of some 70 or so 68030 Motorola processors. This being replaced by the Raytheon AN/BYG-1 combat system. Weapons control is managed by the Raytheon Mk 2 fire control system.

MISSILES

Like the improved Los Angeles class, the Seawolf does not have any external weapons. The submarine is armed with both the land-attack and anti-ship version of the Tomahawk missile from Raytheon. The land-attack Tomahawk has a range of 2,500km. A TAINS (Tercom Aided Inertial Navigation System) guides the missile towards the target flying at subsonic speed at an altitude of 20m to 100m. Tomahawk can be fitted with a nuclear warhead which is not normally carried. Block III improvements include an improved propulsion system and Navstar Global Positioning System (GPS) guidance capability. The anti-ship Tomahawk missile is equipped with an inertial guidance and an active radar and anti-radiation homing head. The range is up to 450km.

First underwater launch of the new Raytheon Tactical Tomahawk Block IV missile took place in November 2002. Block IV includes a two-way satellite link that allows reprogramming of the missile in flight and transmission of Battle Damage Indication (BDI) imagery. The missile entered service with USN surface ships in September 2004.

The Seawolf class also carry the Harpoon anti-ship missile from Boeing. Sub-Harpoon uses active radar homing to deliver a 225kg warhead. The range is 130km and the speed is high subsonic.

TORPEDOES

Seawolf has eight 660mm torpedo tubes for launching torpedoes and missiles. 50 missiles/torpedoes are carried. The Gould Mk-48 ADCAP torpedoes combat both high-performance surface ships and fast deep-diving submarines. The torpedo has a 267kg warhead. It is capable of operating with or without wire guidance and uses either or both active and passive homing. Range is 50km (active) and 38km (passive)

COUNTERMEASURES

Countermeasures include the Northrop Grumman WLY-1 torpedo decoy system and a GTE WLQ-4(V)1 electronic countermeasures (ECM) system.

SENSORS

The submarine's sonar suite is the BQQ 5D with bow-mounted active/passive arrays and wide aperture passive flank arrays. Also fitted are TB-16 surveillance and TB-29 tactical towed arrays, which will be replaced by the TB-29A thin-line towed array being developed by Lockheed Martin, and BQS 24 active sonar for close range detection.

The Seawolf submarines are being upgraded with the Lockheed Martin AN/BQQ-10(V4) sonar processing system under the Acoustic-Rapid Commercial-Off-The-Shelf Insertion (A-RCI) programme.

BPS 16 radar, operating at I-band, is fitted for navigation.

PROPULSION

The nuclear-powered Seawolf has a GE PWR S6W reactor system, two turbines rated 52,000hp (38.8MW), a pumpjet propulsor, a single shaft, and one secondary propulsion submerged motor.

SSBN Vanguard Class Ballistic Missile Submarine, United Kingdom

The Vanguard submarines were built by Vickers Shipbuilding and Engineering Limited (now BAE Systems Marine) at Barrow-in-Furness. They are the largest submarines manufactured in the UK, displacing 15,900t submerged, twice the displacement of the Resolution class Polaris submarines which they replaced.

The first of class, HMS Vanguard, was commissioned in 1993, HMS Victorious in 1995, HMS Vigilant in 1996 and HMS Vengeance in 1999. The Vanguard submarines are based at the Royal Naval Base at Faslane in Scotland.

In February 2002, HMS Vanguard arrived at Devonport Naval Base to begin a two year refit including a new reactor core, which was completed in January 2005.

Following sea trials, which included test launching of Trident II D5 ballistic missiles, the vessel has returned to the fleet. A new dry dock was completed in 2001 for the refit of Vanguard and other RN nuclear-powered submarines. HMS Victorious began refit in January 2005.

MISSILES

The Vanguard has the capacity to carry 16 Trident missiles. The Trident II or D5 missile (designated UGM-133A) is a strategic submarine-launched ballistic missile (SLBM) manufactured by Lockheed Martin Missiles and Space. The missile carries a number of multiple independently targeted re-entry vehicles (MIRVs), each armed with a yield of 100kt to 120kt.

The Trident II missile can carry up to 12 MIRVs but START I treaty agreements limit this to eight. D5 missiles for the Vanguard Class will carry a maximum of four warheads and, in 1999, it was announced that each vessel would carry a maximum of 48 warheads.

Trident II is a three-stage solid propellant missile with supersonic speed. Weight is 59,000kg. The US Navy gives the range of the D5 as 'greater than 7,360km' but this could be up to 12,000km, depending on the payload mix.

The accuracy of strike on the target is given by the Circle of Equal Probability (CEP) value, which is the radius of the circle within which half the strikes will impact. The Mark 6 guidance system on Trident II is a star-sight aided inertial guidance system, which gives a CEP of 120m. The missile is ejected from the submarine by high-pressure gas. When it reaches the surface the first rocket stage fires automatically. The missile's inertial guidance system calculates flight behaviour and guidance.

After the third rocket motor has separated, the warhead carrier takes a star-sighting to confirm position and manoeuvres to the point at which the warheads can be released to freefall onto the target.

TORPEDOES

Vanguard is fitted with four 533mm torpedo tubes and carries the Spearfish torpedo supplied by BAE Systems. Spearfish is a heavyweight wire-guided torpedo with both active and passive homing.

It has a speed of 102km/h (55kt) and range of 54km (30nm) at low speed, 26km (12.5nm) at high speed. Length is 7m (23ft), diameter is 533mm (21in) and weight is 1,850kg (4,075lb), with a 300kg (660lb) warhead.

ELECTRONIC WARFARE

The submarine is fitted with two SSE Mark 10 launchers for deployment of Type 2066 and 2071 decoys. The submarine's electronic support measures (ESM) intercept system is the UAP Mark 3 supplied by Thales Defence.

SENSORS

Vanguard is equipped with the Thales Underwater Systems Type 2054 composite sonar system. Type 2054 is a multi-mode multi-frequency suite, which includes the 2046, 2043 and 2082 sonar systems. In September 2006, Lockheed Martin UK was awarded a contract to upgrade the Type 2054 sonar systems.

The upgrade will include open architecture processing using COTS (Commercial Off The Shelf) technology, based on the ARCI (Acoustic Rapid COTS Insertion) model that has been in service with the US Navy since 1998. The upgraded system will enter service from 2009.

The Vanguard's towed sonar array is the Type 2046, which provides passive search capability and operates at very low frequency. The Type 2043 is the hull-mounted active and passive mode search sonar and the Type 2082 sonar provides passive intercept and ranging capability.

The submarine is fitted with the CK51 search periscope and the CH91 attack periscope from Thales (formerly Pilkington) Optronics. These periscopes include TV camera and thermal imager as well as optical channel. All above water sensors are combined into self-protection masts in the submarine's fin.

The submarine's navigation radar is the Type 1007 I-band radar supplied by Kelvin Hughes.

PROPULSION

The Vanguard class submarine's main nuclear powered propulsion system is based on the second-generation Rolls-Royce PWR 2, which was developed specifically for the Vanguard Class. Current generations of PWR allow submarines to circumnavigate the world about 20 times, whereas the latest development of PWR would allow circumnavigation 40 times without refuelling.

The other main items of machinery are two GEC turbines, and a single shaft with a pump jet propulsor. There are two Paxman diesel alternators, and two turbo generators from WH Allen. The propulsion system provides a maximum submerged speed of 25 knots.

NSSN Virginia Class Attack Submarine, USA

The Virginia Class new attack submarine is an advanced stealth multi-mission nuclear-powered submarine for deep ocean anti-submarine warfare and littoral (shallow water) operations.

Although the Seawolf submarine was developed to provide an eventual replacement for the US Navy Los Angeles Class submarines in combating the Soviet forces, the prohibitive unit cost and changing strategic requirements led to the US Navy defining a smaller new-generation attack submarine.

The Electric Boat division of General Dynamics, Connecticut is the lead design authority for the Virginia Class. General Dynamics Electric Boat has built the first of class – Virginia (SSN 774) and Northrop Grumman Newport News the second – Texas (SSN 775).

The subsequent vessels will be: Hawaii (SSN 776) and New Hampshire (SSN 778), being built by Electric Boat, and North Carolina (SSN 777) and New Mexico (779), being built by Newport News.

The US Navy's total requirement is for 30 of the class. It placed a bulk-buy contract for the first five ships and, in January 2004, placed a multi-year contract for the following five.

Virginia was laid down in September 1999, launched in August 2003 and commissioned in October 2004. It is undergoing a three-year operational evaluation before operational deployment. Texas was launched in April 2005, delivered in June 2006 and commissioned in September 2006. The keel for Hawaii was laid in August 2004, it was launched in June 2006 and commissioned in May 2007.

North Carolina was launched in May 2007 and delivered in December 2007, and will be commissioned in April 2008. New Hampshire will be delivered in 2010 and New Mexico in 2011. SSN 780 began construction in December 2004 but is as yet unnamed.

DESIGN

The engineering teams and the design and build teams at Electric Boat in partnership with the Naval Sea Systems Command, NAVSEA, of the US Navy have used extensive CAD/CAE simulation systems to optimise the design of the submarine. The hull size is length 377ft by beam 34ft and the displacement is 7,300t dived, which is smaller than the more expensive Seawolf Attack Submarine with displacement 9,137t dived.

The hull structure contains structurally integrated enclosures, which accommodate standard 19in and 24in width equipment for ease of installation, repair and upgrade of the submarine's systems.

The submarine is fitted with modular isolated deck structures, for example the submarine's command centre will be installed as one single unit resting on cushioned mounting points. The submarine's control suite is equipped with computer touch screens. The submarine's steering and diving control is via a four-button, two-axis joystick.

The noise level of the Virginia is equal to that of the US Navy Seawolf, SSN 21, with a lower acoustic signature than the Russian Improved Akula Class and fourth-generation attack submarines. To achieve this low acoustic signature, the Virginia incorporates newly designed anechoic coatings, isolated deck structures and a new design of propulsor.

Goodrich is supplying high-frequency sail array acoustic windows and composite sonar domes.

COMMAND SYSTEM

The Command and Control Systems Module (CCSM) is being developed by a team led by Lockheed Martin Naval Electronics & Surveillance Systems – Undersea Systems (NE&SS-US) of Manassas, Virginia. It will integrate all of the vessel's systems – sensors, countermeasures, navigation, weapon control, and will be based on open system architecture (OSA) with Q-70 Colour Common Display Consoles.

Weapon control will be provided by Raytheon with a derivative of the CCS Mk 2 combat system, the AN/BYG-1 combat control system, which is also being fitted to the Australian Collins Class submarines.

The Virginia has two mast-mounted Raytheon Submarine High Data Rate (Sub HDR) multi-band satellite communications systems that allow simultaneous communication at Super High Frequency (SHF) and Extremely High Frequency (EHF).

WEAPON SYSTEMS

The submarine is equipped with 12 vertical missile launch tubes and four 533mm torpedo tubes. The vertical launching system has the capacity to launch 16 Tomahawk Submarine-Launched Cruise Missiles (SLCM) in a single salvo. There is capacity for up to 26 Mk 48 ADCAP Mod 6 heavyweight torpedoes and sub harpoon anti-ship missiles to be fired from the 21in torpedo tubes. Mk 60 CAPTOR mines may also be fitted.

An integral lock-out / lock-in chamber is incorporated into the hull for special operations. The chamber can host a mini-submarine, such as Northrop Grumman's Oceanic and Naval Systems Advanced SEAL Delivery System (ASDS), to deliver special warfare forces such as Navy Sea Air Land (SEAL) teams or Marine reconnaissance units for counter-terrorism or localised conflict operations.

COUNTERMEASURES

Virginia will be fitted with the AN/WLY-1 acoustic countermeasures system being developed by Northrop Grumman, which provides range and bearing data, and the mast-mounted AN/BLQ-10 Electronic Support Measures (ESM) system from Lockheed Martin Integrated Systems.

AN/BLQ-10 provides full spectrum radar processing, automatic threat warning and situation assessment.

SENSORS

The Virginia Class sonar suite will include bow-mounted active and passive array, wide aperture passive array on flank, high-frequency active arrays on keel and fin, TB 16 towed array and the Lockheed Martin TB-29A thinline towed array, with the AN/BQQ-10(V4) sonar processing system. A Sperry Marine AN/BPS-16(V)4 navigation radar, operating at I-band, is fitted.

The submarines will have two Kollmorgen AN/BVS-1 photonic masts, rather than optical periscopes. Sensors mounted on the non-hull-penetrating photonic mast include LLTV (Low-Light TV), thermal imager and laser rangefinder. The mast is the Universal Modular Mast developed by Kollmorgen and its Italian subsidiary, Calzoni.

The Boeing LMRS Long-term Mine Reconnaissance System will be deployed on the Virginia Class. LMRS includes two 6m autonomous unmanned underwater vehicles, an 18m robotic recovery arm and support electronics.

Northrop Grumman Electronic Systems is supplying the LightWeight, Wide-Aperture Array (LWWAA) system based on fibre-optic arrays, instead of traditional ceramic hydrophone sensors. LWWAA is a passive ASW sonar system which consists of three large array panels mounted on either side of the submarine's hull.

PROPULSION

The main propulsion units are the GE pressure water reactor S9G, designed to last as long the submarine, two turbine engines with one shaft and a United Defense pump jet propulser, providing 29.84MW. The speed is over 25kt dived.

SSN Astute Class Attack Submarine, United Kingdom

The Royal Navy's Astute Class submarine is a nuclear-powered attack submarine which is to replace the five Swiftsure Class submarines, launched between 1973 and 1977 and approaching the end of their operational life.

The initial order quantity is three, but the UK MOD has stated that it is planning a second batch of three. The performance specification of the Astute is an extension of the performance of the Trafalgar Class Batch 1 fleet of the Royal Navy's Second Submarine Squadron based at Devonport. The Astute Class submarines will be based at Faslane in Scotland.

BAE Systems Astute Class Ltd is prime contractor for the project and the submarines are being built at BAE Systems Marine Barrow shipyard. The Astute ships are to be named Astute, Ambush and Artful.

It is planned that the three submarines will enter service in 2009, 2010 and 2011. The keel for the first-of-class Astute was laid in January 2001 and it was launched on 8 June 2007.

Astute is planned to be delivered in August 2008 and enter service in January 2009. The keel of Ambush was laid in October 2003 and that of Artful in March 2005.

In May 2007, the UK MOD awarded BAE Systems a contract to build a fourth Astute Class submarine, HMS Audacious, to enter service in 2013.

In October 2007, Astute made her first dive, for an underwater test of systems, at the 'dive hole' in Devonshire Dock, Barrow. Also in October the vessel successfully carried out first firing trials from its torpedo tubes.

Trafalgar Batch 1 submarines are to be decommissioned by 2022, beginning with HMS Trafalgar in 2008

COMBAT SYSTEM

The Astute Combat Management System (ACMS) is being supplied by BAE Systems Insyte (formerly Alenia Marconi Systems) and is a development of the Submarine Command System (SMCS) currently in service in all classes of UK submarines.

ACMS receives data from the sonars and other sensors and, through advanced algorithms and data handling, displays real time images on the command consoles. Factory acceptance of the operational software was received from the Astute Prime Contract Office in July 2002.

EADS Defence & Security Systems Ltd and EADS Hagenuk Marinekommunikation were awarded the contract to provide the external communications systems for the Astute in August 2005.

Strachan and Henshaw are to provide the Weapon Handling and Launch System (WHLS).

MISSILES

The Astute will be equipped with the Tomahawk Block IV (Tactical Tomahawk) cruise missile from Raytheon fired from the 533mm torpedo tubes.

Tomahawk is equipped with the TERCOM terrain contour mapping-assisted inertial navigation system. The terrain contour mapping for use over land combines onboard radar altimeter measurements with terrain mapping data installed in the missile.

Block II added Digital Scene Matching Area Correlation (DSMAC) guidance. Block III improvements include an improved propulsion system and Navstar Global Positioning System (GPS) guidance capability. The GPS provides location and velocity data of the missile for precision targeting.

Tomahawk has a range of up to 1,000 miles and a maximum velocity of 550mph. Block IV includes a two-way satellite link that allows reprogramming of the missile in flight and transmission of Battle Damage Indication (BDI) imagery.

TORPEDOES

Astute will have six 533mm torpedo tubes, and will be equipped with Spearfish torpedoes and mines. There is capacity for a total of 36 torpedoes and missiles.

The Spearfish torpedo from BAE Systems is wire-guided with an active / passive homing head. The range is 65km at 60kt. Spearfish is fitted with a directed-energy warhead.

COUNTERMEASURES

The countermeasures suite will include decoys and Electronic Support Measures (ESM). The The ESM system is the Thales Sensors Outfit UAP(4). Outfit UAP(4) has two multi-function antenna arrays which are mounted on the two non-hull penetrating optronics masts from Thales (formerly Pilkington) Optronics and McTaggart Scott.

Astute Class submarines are to be fitted with the Royal Navy's new Eddystone Communications band Electronic Support Measures (CESM) system, also to be fitted to the Trafalgar Class submarines. The Eddystone system is being developed by DML of Devonport UK, with Argon ST of the USA. It will provide advanced communications, signal intercept, recognition, direction-finding and monitoring capability.

SENSORS

Astute is fitted with I-band navigation radars. The sonar is the Thales Underwater Systems (formerly Thomson Marconi Sonar) 2076 integrated passive / active search and attack sonar suite with bow, intercept, flank and towed arrays. Sonar 2076 has so far been fitted to Trafalgar Class submarines Torbay, Trenchant and Talent, and entered service in February 2003.

Atlas Hydrographic will provide the DESO 25 high-precision echosounder, to be fitted on the Astute. DESO 25 is capable of precise depth measurements down to 10,000m.

Astute will have two non-hull-penetrating CM010 optronic masts developed by Thales Optronics. McTaggart Scott will supply the masts. The CM010 mast includes thermal imaging, low light TV and colour CCD TV sensors.

Raytheon Systems Ltd has been contracted to provide the Successor IFF (Identification Friend or Foe) naval transponder system for the Astute

PROPULSION

The nuclear power will be provided by the Rolls-Royce PWR 2 pressurised water reactor. The long-life core fitted on the PWR 2 means that refuelling will not be necessary in the service life of the submarine.

The other main items of machinery are two Alsthom turbines, and a single shaft with a Rolls-Royce pump jet propulsor, consisting of moving rotor blades within a fixed duct. There are two diesel alternators, one emergency drive motor and one auxiliary retractable propeller. CAE Electronics is to provide the digital, integrated controls and instrumentation system for steering, diving, depth control and platform management.

The PWR 2 second-generation nuclear reactor was developed for the Vanguard Class Trident submarines. Current generations of PWR would allow submarines to circumnavigate the world about 20 times, whereas the latest development of PWR would allow circumnavigation 40 times without refuelling.

The major equipment components in the development of PWR 2 are the reactor pressure vessels from Babcock Energy, main coolant pumps from GEC and from Weir, and protection and control instrumentation from Siemens Plessey and Thorn Automation.