Barrow Built

Astute Class

Under a £2bn Prime Contract BAE SYSTEMS is undertaking the design, build and initial in-service support of seven 7500 tonne Astute Class Submarines Type SSN for the Royal Navy.

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 are approaching the end of their operational life. The Astute ships are to be named Astute, Ambush, Artful, Audacious, Agamemnon & Anson. The name of the remaining boat has yet to be confirmed. Astute began construction in 2000. The first of class was rolled out on July 8th, 2007.

Artists impression of Astute

With the cancellation of the "W Class" SSN program (also known as the SSN-20 program) the UK Royal Navy then considered a Trafalgar Batch II (Astute) as the option for future SSN requirements. The estimates for this improved hull Trafalgar are were around 30% less than the previously envisioned W Class.

Bold statements were made by industry that these submarines will have over ninety percent of the W Class's performance at only seventy-five percent of the cost. The current Trafalgar class SSNs cost approximately £300m each, and have had an annual operating cost of approximately £10.5 million each (1991/92).

While the claims of industry were enough to continue feasibility studies the realities are beginning to become apparent. Design tradeoffs on construction costs versus life cycle costs have created considerable discussion and have opened the door for different solutions.

One proposal was to further develop and install a whole life core nuclear power plant. has This increased development and production cost estimates yet have significantly reduced life cycle costs as it would not be necessary to refuel these vessels for their projected operational life.

This is the approach which has been chosen for the Astute class. It is expected that the reactor cores will last the full 25-30 years of the Astute boats' life. In 1997 it was said that the new cores would allow the reactors to achieve a 10 per cent reduction in running costs compared to previous British SSNs.

COMBAT SYSTEM

The combat data system is the SMCS tactical data handling system from BAeSEMA. Strachan and Henshaw are to provide the weapon handling and launch system (WHLS).

The submarine launched Harpoon UGM-84 is a sea-skimming anti-ship missile with maximum velocity in excess of 0.8 Mach and range in excess of 70 miles.

MISSILES

The Astute will be equipped with the Tomahawk Block III cruise missile from Raytheon and Submarine Harpoon produced by Boeing, both fired from the 533 mm 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. The Block III improvement package provided an improved propulsion system and terminal guidance and also covered the installation of the Navstar Global Positioning System receiver in the missile. The GPS provides location and velocity data of the missile.

TORPEDOES

Astute will have six 533 mm 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 60 knots. Spearfish is fitted with a directed energy warhead.

COUNTERMEASURES

The countermeasures suite will include decoys and Electronic Support Measures (ESM). The UK Royal Navy has issued a requirement for a new communications band electronic support measures (CESM) to be fitted to the Astute Class (and also the Trafalgar and Swiftsure Class submarines). The system will provide advanced communications, signal intercept, recognition, direction finding and monitoring capability. The submarines are to be fitted with non-hull penetrating ESM masts.

SENSORS

Astute is fitted with I-band navigation radars. The sonar is the Thomson Marconi Sonar 2076 integrated suite with bow, intercept, flank and towed arrays. Astute-class submarines will dispense with conventional periscopes in favour of two non-hull penetrating CM010 optronic masts developed by Pilkington Optronics. McTaggart Scott will supply the masts. The CM010 mast includes thermal imaging, low light TV and colour CCD TV sensors.

PROPULSION

The nuclear power will be provided by the Rolls-Royce PWR 2. The other main items of machinery are two GEC turbines, and a single shaft with a pump jet propulsor. 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.

< BACK