Astute class submarine

HMS Astute on a shiplift
Class overview
Builders:	BAE Systems Submarine Solutions
Operators:	Royal Navy
Preceded by:	Trafalgar class
Built:	2001–present
In commission:	2010–present
Building:	4
Planned:	7
Completed:	2
Active:	1
General characteristics
Class and type:	Nuclear-powered Fleet submarine
Displacement:	7,000 tonnes, surfaced 7,400 tonnes, dived
Length:	97 m (323 ft)
Beam:	11.3 m (37 ft)
Draught:	10 m (33 ft)
Propulsion:	Rolls-Royce PWR 2 reactor, MTU 600 kilowatt diesel generators
Speed:	29+ knots (56+ km/h) submerged
Range:	Only limited by food and maintenance requirements.
Test depth:	Over 300 m
Complement:	98 (capacity for 109)
Sensors and processing systems:	Thales Sonar 2076 Atlas DESO 25 echosounder 2 x Thales CM010 optronic masts Raytheon Successor IFF
Armament:	6 x 21-inch (533 mm) torpedo tubes with stowage for up to 38 weapons; Tomahawk Block IV land-attack cruise missiles Spearfish wire-guided heavyweight torpedoes

The Astute-class is the latest class of nuclear-powered Fleet submarines in service with the Royal Navy. The class sets a new standard for the Royal Navy in terms of weapons load, communication facilities and stealth. The boats are being constructed by BAE Systems Submarine Solutions at Barrow-in-Furness. Seven boats will be constructed. The first of class, Astute, was launched in 2007 and commissioned in 2010, and the second, Ambush, was launched on 6 January 2011, and successfully completed its initial dive test on 30 September 2011.

History

Background

The Royal Navy has changed its submarine-employment strategy from the Cold War emphasis on anti-submarine warfare to the concept of "Maritime Contributions to Joint Operations."

Approval for studies to define the "Batch 2 Trafalgar class" (what would become the Astute class) was given in June 1991. In July 1994 risk reduction studies were authorised in parallel with the formal bid phase of the project.

On 17 March 1997, the Ministry of Defence announced that it would place a £2 billion order for three submarines and that they would be called the Astute class. On 26 March 1997 the contract was signed with GEC-Marconi for the first three boats: Astute, Ambush and Artful. These names were last given to Amphion-class submarines that entered service towards the end of World War II. GEC would build the submarines at its VSEL subsidiary (now BAE Systems Submarine Solutions).

Original plans were for seven boats of the Astute class to replace five Swiftsure-class submarines (Sovereign, Superb, Sceptre, Spartan, and Splendid) and the two oldest Trafalgar-class boats (Trafalgar and Turbulent). The Swiftsure class entered service between 1973 and 1977 and were entirely decommissioned by 2010, when only the first of the Astute class was coming into service. Trafalgar was decommissioned in December 2009, to be followed by Turbulent in 2011.

An estimated 5,900 people are employed directly as a result of the project; 3,500 BAE Systems staff at Barrow and 2,400 other people around the UK.

Batch 2

As of August 2006 BAE Systems was negotiating for a contract to build another four Astute-class submarines (hulls four to seven). The fourth boat was ordered on 21 May 2007, to be called Audacious, and the names of the other hulls have been agreed as Agamemnon, Anson, and Ajax. On 15 September 2011 it was announced that hull 5 would now be named Anson.

Upon the beginning of sea trials of Astute in November 2009, it was reported that long-lead items for hulls five and six have been ordered, including their nuclear reactor cores, and that the stated intention of the MoD was for a total of seven Astute-class submarines.

On 25 March 2010, BAE Systems were given the go-ahead by the government to begin construction on hulls 5 and 6, being given a £300 million contract for the "initial build" of hull five and "long lead procurement activities" for boat six. In the same week the government re-affirmed their commitment to the construction of seven Astute-class submarines.

The order of seven Astute-class boats was confirmed in the Strategic Defence and Security Review of October 2010. In December that year it was confirmed by the MoD that "early work" was under way on boats five and six.

On 13 October 2011, the fifth boat "Anson", was laid down at Devonshire Dock Hall and is now under construction like boats three and four.

Design

General characteristics

Astute-class boats are powered by a Rolls-Royce PWR2 (Core H) (a Pressurised water) reactor and fitted with a pump-jet propulsor. The PWR2 reactor was developed for the Vanguard-class ballistic missile submarines. As a result Astute-class boats are about 30 per cent larger than previous British fleet submarines, which were powered by smaller diameter reactors.

Like all Royal Navy submarines, the bridge fin of the Astute-class boats is specially reinforced to allow surfacing through ice caps. The class submarines can also be fitted with a dry deck shelter which allows special forces (e.g. SBS and SAS) to deploy whilst the submarine is submerged.

Sonar signature reduction

More than 39,000 acoustic tiles mask the vessel's sonar signature, giving the Astute class a better stealth quality than any other submarine previously operated by the Royal Navy. Speculation released by the media stated that by using advanced stealth technology Astute "makes less noise than a baby dolphin, making her as good as undetectable by enemy ships."

Astute on the shiplift after launch.

Weapons and systems

The Astute class has stowage for 38 weapons and would typically carry both Spearfish heavy torpedoes and Tomahawk Block IV cruise missiles, the latter costing £870,000 each. The Tomahawk missiles are capable of hitting a target to within a few meters within a range of 1,240 miles (over 2,000 km). The Astute class will also be able to fire the new "tactical Tomahawk" currently under development.

The Astute Combat Management System is an evolved version of the Submarine Command System used on other classes of British submarine. The system receives data from the boat's sensors and displays real time imagery on all command consoles. The submarines also have Atlas Hydrographic DESO 25 high-precision echosounders, two CM010 non-hull-penetrating optronic masts - in place of conventional periscopes - which carry thermal imaging and low-light TV and colour CCD TV sensors.

The vessel is equipped with the advanced Thales Underwater Systems Sonar 2076, which is an integrated passive/active search and attack sonar suite with bow, intercept, flank and towed arrays. BAE claims that the 2076 represents a "step change" over previous sonars and is the world's most advanced and effective sonar system.

It also mounts a Raytheon Systems Ltd Successor IFF system

Crew comforts

Astute is the first Royal Navy submarine class to have a bunk for each member of the ship's company, ending the practice of 'hot bunking', whereby two sailors on opposite watches shared the same bunk. However, they have less mess-deck space than the Valiant-class submarine built 45 years earlier.

Boats

Name	Hull	Pennant number	Status	Ordered	Laid down	Launched	Date of commission
HMS Astute	1	S119	Commissioned	March 1997	31 January 2001	8 June 2007	27 August 2010
HMS Ambush	2	S120	On sea trials	March 1997	22 October 2003	6 January 2011	In service 2013
HMS Artful	3	S121	Under construction	March 1997	11 March 2005		In service 2015
HMS Audacious	4	S122	Under construction	May 2007	24 March 2009		In service 2018
HMS Anson	5	S123	Under construction	March 2010	13 October 2011		In service 2020
HMS Agamemnon	6	S124	On order; long-lead items ordered	March 2010			In service 2022
HMS Ajax	7	S125	Confirmed, order not yet placed				In service 2024

Construction and delays

BAE Systems issued a profit warning on 11 December 2002 as a result of the cost overruns and delays it was experiencing with the Astute class and also the Nimrod MRA4 maritime reconnaissance/attack aircraft. The delay was caused primarily by the problems of using 3D CAD; Armed Forces Minister Adam Ingram said in 2006 that "due to the complexity of the programme, the benefits that CAD was envisaged to provide were more difficult to realise than either MoD or the contractor had assumed." Other issues were the insufficient capabilities within GEC-Marconi which became evident after contract-award and poor programme management. BAE and the Ministry of Defence reached an agreement in February 2003 whereby they would invest £250 million and £430 million respectively to address the programme's difficulties.

A major element of this was the enlisting of advice and expertise from General Dynamics Electric Boat. The MoD also signed a design and production drawing work contract through the U.S. Navy which ran from 2004 to 2007.

Work on the second and third submarines, Ambush and Artful, proceeded well with major milestones such as the closure of Ambush's reactor compartment, demonstrating significant schedule advance compared with Astute. BAE Systems and the MoD have made efforts to reduce costs and achieved significant cost-cutting and productivity gains. A £580 million cost increase was agreed in 2007 due to maturing of the design requiring more materials, inflationary costs, and "some programme throughput assumptions at the Barrow site not being borne out."

First-of-class HMS Astute was launched by Camilla, Duchess of Cornwall on 8 June 2007.

As of March 2008 the programme was 48 per cent (or £1.2 billion) over-budget and 47 months late. Further delays due to a range of technical and programme issues brought the programme to a position of 57 months late and 53 per cent (or £1.35 billion) over-budget by November 2009, with a forecast cost of £3.9 billion for the first three Astute boats.

See also

• List of submarines of the Royal Navy
• Future of the Royal Navy

External links

• BAE Systems Astute Microsite
• Cutaway Diagram(pdf)
• Navy Matters - Astute Class
• BAE Systems: Murray Easton Interview
• How to Build a Nuclear Submarine. BBC Television documentary, first broadcast 27 Jun 2010.