Sweden's A19 Gotland class are the first submarines in the world to feature a Stirling engine air-independent propulsion (AIP) system. With her Stirling AIP (Air Independent System), Swedish Navy submarines are able to remain submerged for weeks at a time, without having to surface and thereby risk detection. The Stirling system is an important element of the overall stealth concept. Much else is involved, however, such as various forms of signature reduction and the elimination of noise.
Typical missions include anti shipping operation, anti submarine warfare missions, forward surveillance, special operations and minelaying. Gotland class submarines can carry a powerful range of wire-guided and homing torpedoes, missiles and mines. The Gotland class is the world's first conventional submarine designed specifically to incorporate an AIP system. This, combined with low underwater signatures and target strengths, ensures the ultimate in underwater stealth. The Gotland class can operate independently of any major infrastructure facilities ashore. The fuels used is widely available and weapons can be reloaded with the aid of a small crane, giving the Gotland class a very high operational value.
A very high degree of automation and remote control enables the Gotland class to operate with a relatively small crew. This not only minimises operating costs: it permits a higher standard of crew accommodation. The Combat Management System handles detection, identification, weapons launch and control at distances well beyond the horizon. All weapons can be launched in rapid succession and guided simultaneously toward individual targets. The Combat Management System includes an effective sonar suite with circular, intercept and flank arrays. The Gotland class also possesses extremely high shock endurance, enhancing survivability.
In the context of the new rapid reaction force, the submarine's multi-mission capability is especially useful, as is the ability to operate unseen. In particular, the submarine has developed into a superb surveillance platform, which can see and hear over huge distances while able to remain undetected.In the strictly naval context, the submarine is also well suited to operate as a subsurface command centre. Another advantage is that submarines permit great freedom of action, when the decision to act is restricted by political uncertainty. The fact is that submarines operate mainly in international waters. And high-risk operations can be conducted on a clandestine basis.
These submarines are conventional submarines equipped with a machinery (Stirling) which is independent of air supply. This allows the submarines to operate submerged throughout several weeks, a fact that makes these submarines unique.Compared with other submarines the Gotland class is a relatively small submarine, containing long endurance and advanced technology and it is probably the most silent of today's conventional submarines. Shortly - the Swedish Armed Forces today have three of the most modern conventional submarines in the world.
The main roles envisaged for the Gotland boats are attack, surveillance, minelaying and ASW. Externally the single-hull Gotland is very similar to the Södermanland class (Type A 17), but has improved performance in submerged endurance, and with increased stealth capability afforded by anechoic tiles that are fitted to the hull. All equipment is resiliently mounted and major platform decks and all equipment are carried on rubber mountings to isolate them from the hull.
The hull is divided into two watertight compartments separated by a tank section, which incorporates a one-man escape chamber accessible from both compartments. A DSRV or a rescue bell can be mated to the chamber. The forward compartment is divided into two decks, the lower deck housing the four 533 mm and two 400 mm bow torpedo tubes and associated weapon handling gear and reload racks. Beneath this compartment is the battery space and auxiliary machinery. The upper deck houses the control room, accommodation and other equipment rooms associated with the sensors and communications. The aft compartment houses the diesel generator sets and more battery space, as well as auxiliary machinery and propulsion control equipment. This aft section also contains the Air-Independent Propulsion (AIP) machinery and electric motor. In the aft section are installed two Stirling V4-275R AIP Mk 2 systems developed by Kockums using liquid oxygen and diesel in a helium environment.
The submarine is equipped with two MTU diesel engines and two Kockums V4-275R Stirling Air Independent Propulsion units. The Stirling engines are mounted in elastic, soundproof modules and each provide up to 75 kW. The submarine has the capacity for two weeks of air independent propulsion at a speed of 5 knots without snorting. The AIP uses liquid oxygen and diesel fuel in a controlled inert (helium) environment. The AIP liquid oxygen tanks are located on the deck below the engines. The propulsion system provides a speed of 11 knots surfaced and 20 knots dived.
The Gotland is manned by a complement of 28 crew and 5 officers The submarines are fitted with four 21 inch torpedo tubes taking the Bofors Torpedo 2000, and two 15.75 inch torpedo tubes taking the Bofors Underwater Systems Type 613 torpedo. The Gotland can also be used to deploy the Bofors Underwater Systems stand-off self-deployed Mine 42. The submarine also has the capacity to carry 48 mines mounted externally in a girdle arrangement. The ship's combat management system is the 9SCS Mark 3 from CelsiusTech. The system carries the Swedish Royal Navy designation SESUB 940A. The system uses an extended version of the ADA software from CelsiusTech's 9LV Mk 3 surface ship combat management system.
The fire control system has the capacity to control several torpedoes in the water simultaneously. The new application software includes target motion analysis developed by Kockums and the University of Lund at Malmo. Kockums have also been responsible for the development of enhanced software for navigation, for torpedo tube control and torpedo tube simulation. The 9SCS Mark 3 Combat Management System has three multifunction consoles, Type IID from Terma. The terminals are for command and control, communications, and weapon control. The consoles are connected via a dual Ethernet copper wire local area network. The combat management system receives data from the submarines' sensors. The submarine is equipped with a CSU 90-2 integrated sonar sensor suite from STN Atlas Elektronik. This includes a passive cylindrical bow array, an intercept array and two passive flank arrays. The sonar system uses ADA software. The submarine is equipped with a Kollmorgen search and attack periscope and a Terma Scanter navigation radar.
The electronic support measures system is the Racal Thorn Manta radar surveillance and warning system as deployed on the British Royal Navy Oberon and Churchill class submarines. Manta carries out surveillance, detection, analysis, classification and identification of hostile radar threats from D-band to J-band. The Manta system also provides a prediction of the detectability of the host submarine by the threat radar using a combination of data from the hostile radar frequency, the sea state and the configuration of the submarine's periscope assembly.
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