Editing Astute-class submarine (section)

==Characteristics==

===Weapons and systems===
[[File:Royal Navy Submarine HMS Astute Fires a Tomahawk Cruise Missile (TLAM) During Testing Near the USA MOD 45153387.jpg|thumb|''[[HMS Astute (S119)|Astute]]'' firing a [[Tomahawk (missile family)|Tomahawk]] Block IV cruise missile]]
The ''Astute'' class has stowage for 38 weapons and would typically carry a mix of [[Spearfish torpedo|Spearfish]] heavy torpedoes and [[Tomahawk (missile family)|Tomahawk]] Block IV cruise missiles,<ref name=38weapons>{{Cite web|date=2021-11-25|title=Astute versus Virginia: which nuclear-powered sub is the best fit for Australia?|url=https://www.aspistrategist.org.au/astute-versus-virginia-which-nuclear-powered-sub-is-the-best-fit-for-australia/|access-date=2021-12-23|website=The Strategist|language=en-AU|archive-date=23 December 2021|archive-url=https://web.archive.org/web/20211223142909/https://www.aspistrategist.org.au/astute-versus-virginia-which-nuclear-powered-sub-is-the-best-fit-for-australia/|url-status=live}}</ref> the latter costing £870,000 each.<ref>{{cite web |title=House of Commons Hansard - Written Answers for Daily Hansard - Written Answers 17 May 2011 |url=https://publications.parliament.uk/pa/cm201011/cmhansrd/cm110517/text/110517w0001.htm |publisher=UK Parliament |date=17 May 2011 |access-date=6 November 2011 |archive-date=11 October 2017 |archive-url=https://web.archive.org/web/20171011185736/https://publications.parliament.uk/pa/cm201011/cmhansrd/cm110517/text/110517w0001.htm |url-status=live }}</ref> The Tomahawk missiles are capable of hitting a target to within a few metres, to a range of {{convert|1000|mi|km|abbr=off}}.<ref>{{cite web|title=United States Navy Fact File: Tomahawk Land Attack Missile|url=http://www.navy.mil/navydata/fact_display.asp?cid=2200&tid=1300&ct=2|website=navy.mil|publisher=US Navy|access-date=27 July 2016|archive-date=27 August 2017|archive-url=https://web.archive.org/web/20170827150407/http://www.navy.mil/navydata/fact_display.asp?cid=2200&tid=1300&ct=2|url-status=dead}}</ref> In May 2022, the MOD announced that it would be upgrading these missiles to Block V standard from 2024, which boasts an extended range and modernised in-flight communication and target selection.<ref name="block5">{{cite news |title=£265 million missile upgrade for UK submarines |url=https://www.gov.uk/government/news/265-million-missile-upgrade-for-uk-submarines |access-date=4 June 2022 |work=[[GOV.UK]] |date=31 May 2022 |archive-date=12 December 2022 |archive-url=https://web.archive.org/web/20221212171623/https://www.gov.uk/government/news/265-million-missile-upgrade-for-uk-submarines |url-status=live }}</ref> The Astute Combat Management System is a new version of the [[SMCS|Submarine Command System]] used on other classes of British submarine. The system receives data from the boat's sensors and displays the results on command consoles. The submarines also have [[Atlas Elektronik|Atlas Hydrographic]] DESO 25 high-precision echosounders, two CM010 non-hull-penetrating [[Photonics mast|optronic masts]]—in place of conventional [[periscope]]s—which carry thermal imaging and low-light TV and colour [[Charge-coupled device|CCD]] TV sensors.<ref name="BBCNewsSco1">[[BBC News]] Scotland, ''[http://news.bbc.co.uk/1/hi/scotland/6969958.stm A vision of evolving technologies] {{Webarchive|url=https://web.archive.org/web/20070911183257/http://news.bbc.co.uk/1/hi/scotland/6969958.stm |date=11 September 2007 }}'' 30 August 2007, 13:06 GMT</ref> The class also mounts a [[Identification friend or foe|Successor IFF]] system.

For detecting enemy ships and submarines, the ''Astute'' class is equipped with the sophisticated [[Sonar 2076]], an integrated passive/active search and attack [[sonar]] suite with bow, intercept, flank and towed arrays. BAE claims that the 2076 is the world's best sonar system.<ref>{{citation|url=http://www.baesystems.com/Newsroom/NewsReleases/2002/press_15052002.html |publisher=BAE Systems |title=Press Release |year=2002 |url-status=dead |archive-url=https://web.archive.org/web/20100909065129/http://www.baesystems.com/Newsroom/NewsReleases/2002/press_15052002.html |archive-date=9 September 2010 }}</ref> All of the Astute-class submarines will be fitted with the advanced Common Combat System.<ref>{{cite web|url=http://www.royalnavy.mod.uk/news-and-latest-activity/news/2016/february/29/160229-artful-test-fire|title=HMS Artful test fires first torpedo using new UK-made advanced Combat System - Royal Navy|access-date=25 July 2016|archive-date=30 April 2016|archive-url=https://web.archive.org/web/20160430230318/http://www.royalnavy.mod.uk/news-and-latest-activity/news/2016/february/29/160229-artful-test-fire|url-status=live}}</ref>

===Propulsion and general specifications===
The boats of the ''Astute'' class are powered by a Rolls-Royce [[Rolls-Royce PWR#PWR2|PWR2]] (Core H) (a [[pressurised water reactor]]) and fitted with a [[pump-jet]] propulsor. The PWR2 reactor, which was developed for the ''Vanguard''-class ballistic missile submarines, has a 25-year lifespan without the need for refuelling.<ref name="tna3b">{{cite web|url=https://rina.org.uk/publications/warship-technology/project-aukus-achieving-critical-mass-scientifically-and-politically/|title=Achieving Critical Mass with Highly Enriched Uranium 2023|date=26 July 2023|access-date=26 July 2023|publisher=[[Royal Institution of Naval Architects]] by [[Dr MJ Cianni]]|archive-date=26 July 2023|archive-url=https://web.archive.org/web/20230726080646/https://rina.org.uk/publications/warship-technology/project-aukus-achieving-critical-mass-scientifically-and-politically/|url-status=live}}</ref><ref name="BAEAstute2016"/> As a result, the new submarines 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. These submarines can also be fitted with a [[dry deck shelter]], which allows special forces (e.g. [[Special Boat Service|SBS]]) to deploy whilst the submarine is submerged.<ref>{{cite web|url=http://www.rusi.org/downloads/assets/Willet.pdf |title=Dr Lee Willett, The ''Astute''-Class Submarine, Capabilities and Challenges, RUSI (2004) |access-date=7 November 2011 |url-status=dead |archive-url=https://web.archive.org/web/20110928105319/http://www.rusi.org/downloads/assets/Willet.pdf |archive-date=28 September 2011 }}</ref> More than 39,000 [[Anechoic tile|acoustic tiles]] mask the vessel's sonar signature, part of the acoustic qualities that the ''Astute'' class has over any other submarine previously operated by the Royal Navy.<ref>{{cite web |url=http://www.shippingtimes.co.uk/item577_astute.htm |title=Countdown to launch of first ''Astute'' submarine at Barrow shipyard |publisher=Shippingtimes.co.uk |access-date=7 November 2011 |archive-date=24 July 2011 |archive-url=https://web.archive.org/web/20110724093014/http://www.shippingtimes.co.uk/item577_astute.htm |url-status=dead }}</ref>

A 2009 safety assessment by the Defence Nuclear Safety Regulator concluded that PWR2 reactor safety was significantly short of good practice in two important areas: [[loss-of-coolant accident]] and control of submarine depth following emergency reactor shutdown.<ref>{{Citation |chapter-url=http://robedwards.typepad.com/files/declassified-report-to-mod-defence-board.pdf |title=Successor Submaring Project - Update |chapter=Annex B: Successor SSBN - Safety Regulator's advice on the selection of the propulsion plant in support of the future deterrent (4 November 2009) |page=21 |publisher=Ministry of Defence |date=24 November 2009 |id=EC-14-02-02-01-14 / Annex B: DNSR/22/11/2 |access-date=28 March 2011 |archive-date=17 April 2011 |archive-url=https://web.archive.org/web/20110417133948/http://robedwards.typepad.com/files/declassified-report-to-mod-defence-board.pdf |url-status=live }}</ref> The regulator concluded that PWR2 was "potentially vulnerable to a structural failure of the primary circuit", which is a failure mode with significant safety hazards to crew and the public.<ref name="dm-20110518">{{Cite news |url=http://www.defencemanagement.com/news_story.asp?id=16337 |title=PWR3 Reactor chosen for Trident |publisher=defencemanagement.com |date=18 May 2011 |archive-url=https://web.archive.org/web/20110722100732/http://www.defencemanagement.com/news_story.asp?id=16337 |archive-date=22 July 2011}}</ref> Operational procedures have been amended to minimise these risks.<ref>{{Cite news |url=http://www.mod.uk/DefenceInternet/DefenceNews/EquipmentAndLogistics/CsaSafetyParamountForRnNuclearSubmarineReactors.htm |title=CSA: Safety paramount for RN nuclear submarine reactors |work=Defence News |publisher=Ministry of Defence |date=9 June 2011 |access-date=17 June 2011 |archive-date=23 June 2011 |archive-url=https://web.archive.org/web/20110623152331/http://www.mod.uk/DefenceInternet/DefenceNews/EquipmentAndLogistics/CsaSafetyParamountForRnNuclearSubmarineReactors.htm |url-status=live }}</ref>

''Astute'' is the second Royal Navy submarine class, after the ''Vanguard'' class, to have a bunk for each member of the ship's company,<ref>{{Cite web |url=http://production.investis.com/astute/media/press/2007-06-08a/ |title=''Astute'' Fascinating Facts |access-date=10 December 2012 |archive-date=21 July 2013 |archive-url=https://web.archive.org/web/20130721140936/http://production.investis.com/astute/media/press/2007-06-08a |url-status=live }}</ref> ending the practice of '[[Hot racking|hot bunking]]', whereby two sailors on opposite watches shared the same bunk at different times. However, they have less mess-deck space than the {{sclass|Valiant|submarine}}s built 45 years earlier<ref>{{Cite web |url=http://www.whatdotheyknow.com/request/52005/response/144718/attach/5/Pdf%20DNP%20HR%20Study%20Redacted%202.pdf |title=Defence Nuclear Programme Human Resource Study |publisher=Ministry of Defence |date=1 July 2009 |id=Defence Board (09)33 |access-date=16 April 2011 |archive-date=8 October 2012 |archive-url=https://web.archive.org/web/20121008181348/http://www.whatdotheyknow.com/request/52005/response/144718/attach/5/Pdf%20DNP%20HR%20Study%20Redacted%202.pdf |url-status=live }}</ref> and a Defence Board audit recognised mistakes had been made on accommodation standards and quality of life issues.<ref>{{Cite web |url=http://www.whatdotheyknow.com/request/52005/response/144718/attach/6/Pdf%20DOC%20Audit%20Redacted.pdf |title=Defence Nuclear Programme Human Resources Study - An Audit by Defence Operational Capability |publisher=Ministry of Defence |date=1 July 2010 |id=Defence Board (10)XX |accessdate=16 April 2011 |quote=Recommendation ... on-board accommodation standards and quality of life issues are thoroughly addressed in order to avoid the mistakes made with the ''Astute'' class. |archive-date=8 October 2012 |archive-url=https://web.archive.org/web/20121008181405/http://www.whatdotheyknow.com/request/52005/response/144718/attach/6/Pdf%20DOC%20Audit%20Redacted.pdf |url-status=live }}</ref> Since it is nuclear powered, the boat has theoretically unlimited endurance, though in practice it is limited to 90 days at sea based on food carried (including 18,000 sausages and 4,200 [[Weetabix]]) and crew endurance.<ref name="BAEAstute2016"/>

In 2012, during the joint exercise Fellowship, ''Astute'' performed simulated battles with the latest United States Navy {{sclass|Virginia|submarine|1}}, {{USS|New Mexico|SSN-779|6}}. Royal Navy Commander Iain Breckenridge was quoted, "Our sonar is fantastic and I have never before experienced holding a submarine at the range we were holding USS ''New Mexico''. The Americans were utterly taken aback, blown away with what they were seeing".<ref>{{cite web|url=https://www.gov.uk/government/news/hms-astute-arrives-home-from-us-sea-trials--2|title=HMS Astute arrives home from US sea trials - Announcements - GOV.UK|access-date=25 July 2016|archive-date=18 September 2016|archive-url=https://web.archive.org/web/20160918032321/https://www.gov.uk/government/news/hms-astute-arrives-home-from-us-sea-trials--2|url-status=live}}</ref>

The ''Astute'' class are designed to achieve a top speed of {{convert|29|-|30|kn|km/h}}, but it was reported in 2012 that this speed could not be reached in trials due to a mismatch between the reactor and the turbine.<ref name="guardian-20121115b">{{cite news |url=https://www.theguardian.com/uk/2012/nov/15/hms-astute-submarine-slow-leaky-rusty |title=Slow, leaky, rusty: Britain's 10bn submarine beset by design flaws |author=Nick Hopkins |newspaper=The Guardian |date=15 November 2012 |access-date=20 November 2012 |location=London |archive-date=31 October 2013 |archive-url=https://web.archive.org/web/20131031121357/http://www.theguardian.com/uk/2012/nov/15/hms-astute-submarine-slow-leaky-rusty |url-status=live }}</ref> However, in January 2015, the [[National Audit Office (United Kingdom)|National Audit Office]] confirmed that demonstration of the top speed requirement (or Key Performance Measure (KPM)) for the ''Astute'' class was successful.<ref name="NAO2014">{{cite book|title=Major Projects Report 2014 and the Equipment Plan 2014 to 2024: Appendices and project summary sheets|date=13 January 2015|publisher=National Audit Office|page=45|url=https://www.nao.org.uk/wp-content/uploads/2015/01/Major-projects-report-2014-appendices-and-project-summary-sheets.pdf|access-date=8 August 2016|archive-date=6 August 2016|archive-url=https://web.archive.org/web/20160806031421/https://www.nao.org.uk/wp-content/uploads/2015/01/Major-projects-report-2014-appendices-and-project-summary-sheets.pdf|url-status=live}}</ref>