Astute Class Nuclear Submarines

Astute-Class Submarines

Astute Class Nuclear Attack Submarines

Astute Class Nuclear Submarines

BAE Systems’ Astute-class submarines are radically overhauling the Royal Navy’s undersea capability. Seven submarines make up the Astute class. The first two are already operational while the remaining five are expected to join them over the coming decade. The full Astute-class fleet will give the Royal Navy its most advanced, stealthiest and comprehensively-armed submarines ever.

The Astute-class submarines are taking over from two previous classes of submarine – the Trafalgar and the Swiftsure. Three Trafalgar-class submarines have already been retired, with the last due to be decommissioned in 2022, while all six Swiftsure-class submarines are already out of service.

Astute-Class Origins

The Astute-class submarines programme took shape throughout the 1990s. The concept of an evolved Trafalgar-class submarine had first emerged in 1991. Bids were invited in mid-1994. Less than three years later – in March 1997 - the Ministry of Defence confirmed it would purchase three of the new submarines. That same month, GEC-Marconi (which later became part of BAE Systems) was contracted to build the trio. By March 2010, contracts existed for six Astute-class submarines’ construction.

Work had started on lead vessel HMS Astute as far back as 2001 but its much-delayed launch didn’t happen until six years after that. Technical issues – Astute and its brethren being the first wholly 3D CAD-generated nuclear submarines – were later given as the reason for this delay.

HMS Astute Launch

HMS Astute was finally launched on 8 June 2007, entered service three years after that and was declared fully operational capable in 2014. Launched in 2011, HMS Ambush joined it under the waves two years later. Both have since been deployed – Ambush taking part in April 2015’s edition of the massive Joint Warrior naval exercise.

HMS Ambush Astute Class Submarine

Next to come after Astute and Ambush will be HMS Artful, due to be commissioned in early 2016. Thereafter, in 2018, it’ll be HMS Audacious’ turn, followed by HMS Anson (2020 commissioning), HMS Agamemnon (2022) and, finally, HMS Ajax (2024).

Astute-Class Construction

A 260-metre-long assembly factory, Devonshire Dock Hall (aka ‘DDH’), is where all Astute-class submarines are pieced together. Located in Barrow-in-Furness, Cumbria, northern England, DDH took four years to build, starting in 1982. It has 25,000 square metres of floor space plus a shiplift that can be loaded with vessels weighing up to 24,300 tonnes. This lift both lowers complete ships into the water and retrieves them and, for a time, it was the world’s largest such structure. Each unfinished Astute-class submarine – Audacious, Anson, Agamemnon and Ajax - is being formed in DDH right now.

HMNB Clyde, sited on Gare Loch, Scotland, will be the homeport for the entire Astute-class fleet. Also based here are the Royal Navy’s four Vanguard-class nuclear-powered ballistic missile submarines – HMS Vanguard, Victorious, Vigilant and Vengeance – and the UGM-133 Trident II missiles they carry.

HMS Astute Roll-Out

Astute – Features And Capabilities

According to BAE Systems, the Astute-class submarines surpass all other attack submarines on several fronts, including weapons capability and overall technology levels incorporated. Laid out end-to-end, each submarine’s cables would cover a distance of some 30 miles. Nuclear-powered, every Astute-class submarine is designed to be able to carry out complete circumnavigations without ever needing to surface. Typically, missions last 90 days, limited only by crew requirements - such as a new consignment of food – while a standard crew comprises 98 personnel. Each crew member on board has his or her own bunk – a step-up from previous arrangements involving shift-based bunk-sharing. Expected service life is 25 years per submarine – the length of time each one’s Rolls-Royce PWR2 (pressurized water) nuclear reactor can remain operational without being refuelled.

The Trafalgar-class submarines were equipped with a Submarine Command System. That’s now been replaced by the all-new Combat Management System, which acquires data picked up by an array of sensors and relays it to all command consoles in real-time. Combining an obstacle-avoidance sonar, active-passive bow sonar and various environmental monitoring equipment, the Thales Underwater Systems Sonar 2076 acts as the Astute-class submarines’ ‘eyes’. Described by BAE Systems as world-beating technology, this sonar system is reportedly as powerful as 60,000 home computers. Another Thales product, the CM010 optronic mast, takes the role of the Astute-class’s ‘ears’. A pair of these equips each submarine, updating the optical periscopes that were traditionally part of earlier designs.

Combat-Management-System

While the Astute-class submarines possess supreme visual and aural senses, what of their own acoustic signatures? No less than 39,000 acoustic tiles help them keep a low profile underwater by absorbing active sonar, to send back a weakened returned signal (thereby making them appear further away than they actually are), and keeping down noise emissions. This feature helps make the Astute-class submarines quieter and stealthier than any preceding submarine that the Royal Navy has used.

Astute-Class Weapons

The Astute-class submarines have the capacity to stow 38 weapons in total. Principally, two types are carried - Spearfish anti-submarine and anti-surface ship warfare torpedoes and Tomahawk Block IV cruise missiles. Manufactured by BAE Systems Underwater Systems, the Spearfish was introduced in 1992. Boasting a 300-kilogram warhead, it has a 54 kilometre range and a maximum speed of 150 kilometres an hour. BAE Systems is now working on an upgraded, fully-digitised Spearfish variant that should enter service early next decade.

The Raytheon BGM-109 Tomahawk Block IV submarine-launched missile has a 450-kilogram warhead fitted and can reach around 890 kilometres per hour over a 1,700 kilometre range. Costing £870,000 apiece, it’s a missile so accurate that it can strike within a few metres of its designated target, even at maximum range.

Astute Tomahawk Missile Launch

Key Facts: HMS Astute

Role: Attack submarine
Length: 318 ft (97 m)
Width: 37 ft (11.3 m)
Engines: One Rolls-Royce PWR2 nuclear reactor
Maximum speed: 35 mph (56 km/h)
Maximum range: Unlimited
Crew: 98-109 personnel
Weapons: Tomahawk Block IV missiles and Spearfish torpedoes
First launched: 8 June 2007

HMS Astute trials image copyright © 2016 BAE Systems.
HMS Ambush arriving at HMNB Clyde photo: LA(Phot) Stu Hill/MOD – courtesy Wikimedia Commons
HMS Astute roll-out pic ©THALES UK
Astute combat management system image copyright © 2016 BAE Systems
Tomahawk missile launch photo: POA(Phot) Paul Punter/MOD – courtesy Wikimedia Commons

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