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.

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 class.

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.


Specifications - SSN Astute Class Attack Submarine, United Kingdom

Key Data

Crew-110 (including 12 officers)
Displacement-7,800t (dived)
Speed-29 knots (dived)


Dimensions

Length-97m
Beam-10.4m
Draught-10m


Weapon Systems

Submarine-Launched Cruise Missile Tomahawk Block III

Torpedoes-6 x 533mm torpedo tubes for missiles and Spearfish torpedo - total of 36 carried.

Combat Data System-Alenia Marconi Systems AMCS

Countermeasures-Outfit UAP(4) ESM, decoys.

Radar-I-band navigation radar

Sonar-Thales Underwater Systems Type 2076