2015-03-24 Last year, the Swedish forces sought to find a mini-sub last October operating in Swedish waters.
As a result of this and other concerns with Russian activity in the region, Sweden is bolstering its defense efforts.
Part of that effort is building new submarines.
According to an AFP story published March 19, 2015:
Last week the Swedish Ministry of Defence announced an order for two new subs. Last week the government announced a 6.2 billion-kronor hike in defense spending largely focused on upgrading its capacity to detect and intercept submarines.
The extra funds would also be used to re-establish a permanent military presence on the strategic Baltic Sea island of Gotland, situated between southern Sweden and Latvia, for the first time in 10 years.
According to SAAB the firm charged with building the Kockums A26:
The new generation, with denomination Kockums A26, will be designed for mainly littoral operations but will also possess ocean-going capabilities.
It will be powered by a conventional diesel-electric propulsion machinery, and equipped with Kockums Stirling AIP system (air-independent propulsion).
The Stirling system, together with a set of balanced underwater signature properties, will make Kockums A26 submarine very stealthy and difficult to detect. It will also be highly invulnerable to underwater explosions through a verified shock resistance.
Kockums A26 design includes a new innovative flexible payload capability with a flexible payload lock system in addition to its conventional torpedo tubes. Furthermore it will be prepared for network connectivity. A highly modular design facilitates efficient through-life upgrades and adaptations.It is now a common assumption that the centre of attention for naval operations has shifted from blue water to the littoral zones of the world. Intelligence gathering, surveillance and sea denial along coastlines are becoming increasingly important. Operations in shallow water enable submarines to carry out covert monitoring of targets on land or sea using a range of electro-optical and electromagnetic sensors. Moreover, the ability of a submarine to lie motionless on the ocean floor, or “bottom out”, makes it almost impossible to find.
SECURING TOTAL CONTROL
Submarine operations in the extreme littorals are also facilitated by the difficulty of carrying out anti-submarine warfare (ASW) in shallow water. A confusing combination of big thermal variations in water layers, unpredictable tides and currents, high reverberation and highly directional ambient noise defeats ASW measures.
This is why the next-generation Kockums A26 submarine, with superior GHOST® (Genuine Holistic Stealth) properties and AIP, is a valuable asset in securing total control in the extreme littoral zones, or as we call it, Littoral Supremacy™.
BLUE WATER CAPABILITY
Not only does the Kockums A26 submarine have excellent transit capability, but it can also operate in big oceans because of its:
- Long transit range
- Extensive endurance
- High snorting speed
- Deep diving ability
- High seakeeping performance
- Excellent crew comfort
Over the last decade, Saab has come a long way in optimizing its GHOST® (Genuine HOlistic STealth) technology, thus making the Kockums A26 submarine effectively invisible as all its signatures are lower than those of the Kockums Gotland-class submarines. Extreme stealth is the heart of the Kockums A26 submarine and it depends on good design right from the very beginning. The holistic nature of optimized GHOST® covers all types of signatures to make it almost impossible to spot during silent service.
A VERY SILENT SUBMARINE
Saab has long experience in designing very silent submarines. In the Kockums A26 submarine, an extremely resilient platform technique incorporating extensive rubber mountings and baffles are used to minimize noise from operating machines and transient noise, as well as absorbing shocks. To further reduce emitted noise, the space between the frames is equipped with acoustic damping plates. This approach is used in combination with, for example, encapsulated Stirling and diesel engine modules; flexible hoses and compensators; and specifying maximum flow speed in air ducts, minimum bending radius on cables and pipes, and the design of outboard holes and cavities.
FURTHER WAYS OF KEEPING SILENT
To become invisible, further ways of keeping silent are exploited by the Kockums A26 AIP submarine: The target strength of the Kockums A26 submarine is minimal because of the vessel’s unique hull shape, the unique fin design, sonar and equipment accommodation, and a new type of surface acoustic absorption or reflection coatings. This highly optimized design also cuts the hydrodynamic signatures and flow noise around the submarine, both in deep water and near the surface.
The magnetic signature is suppressed by an advanced degaussing system that is controlled by external sensors to facilitate compensation in all geographical locations and headings.
Galvanic signatures, primarily electrical but including secondary magnetic signatures are reduced by a specially designed cathodic protection system and careful material selection that minimize electrical signatures without compromising the cor- rosion protection of the submarine.
Radar cross-section has been reduced by carefully analyzing and selecting the masts and mast-mounted sensors along with different coatings.
Infrared signatures are also minimized using different coatings and smart system solutions. In addition, the IR signature is not an issue with the Kockums Stirling AIP engine because the pressure reduction of the exhaust gases reduces the temperature dramatically before they are totally dissolved in sea cooling water and released into the ocean.
HIGHLY INVULNERABLE TO UNDERWATER EXPLOSIONS
The Kockums A26 submarine is designed to withstand significant shock loads from underwater explosions, primarily of mines and depth charges. As mine detection by a submarine takes place at short range, shock resistance is imperative. The hull of the submarine is constructed from special steels and the welding is tested using non-destructive methods to ensure its integrity and pressure-tightness. Materials technology, dimensioning and structural engineering are used to select the best materials to meet specifications, and strict quality assurance is applied to all construction and assembly procedures. All pressure-tight boundaries, including the weapon tube rear doors, are designed to withstand large underwater explosions at a near distance.
SAAB PERFORMS FULL-SCALE SHOCK TESTS
Saab is one of few submarine builders to carry out realistic full-scale shock tests using depth charge explosions at only a few meters from a complete vessel. The submarine is filled with sensors to monitor shock waves at different aspect angles and distances to produce a series of shock acceleration spectra.
Not only do such realistic tests enable Saab to test a hull’s resistance and the response of onboard equipment shocks, but they also provide the crew with valuable experience with explosions. The full-scale shock tests, carried out with a full crew onboard, are part of the acceptance tests for the submarine and also provide invaluable information for Saab to develop its program of continuous improvement.
IN GOOD SHAPE FOR EXCEPTIONAL MANOEUVRABILITY
Being able to quickly turn, rise and dive are valuable tactics when the occasion demands. A number of features makes the Kockums A26 submarine highly manoeuvrable, a feature that contributes significantly to freedom of action. The X-rudder configuration with four independently controlled control surfaces enables the submarine to quickly change position or direction. When submerged, a very tight turning circle can be achieved at all speeds. Moreover, changes in depth can be performed quickly even at low speed because of the well- balanced metacentric height.
A key benefit in the design of the Kockums A26 submarine is its modularity, which provides an amazing degree of opera- tional flexibility, futures-proofs the vessel and contributes significantly to cost-effective construction and assembly. For example, it facilitates:
Flexible payloads – which apply to weapons and sensors, allow for the allocation of space for future but yet to be identi- fied equipment. Up to eight divers including their equipment can be launched and retrieved through the Multimission Portal™. Unmanned underwater vehicles (UUVs), including remotely operated underwater vehicles (ROVs), can also be deployed through the portal.
Payload exchange – adaptable according to mission type. Mast modules can be exchanged, external payload space can be used for different equipment such as pressure-tight containers and underwater vehicles, and reconnaissance and rescue systems can be selected.
Distributed component production and assembly – like pre-outfitted deck platforms, and encapsulated Kockums Stirling AIP and diesel engines.
Extending systems – prepared for future upgrades. For example, a hull section can be inserted in the forward or aft compartment. In the forward section, additional space for accommodation, workstations and other equipment can be inserted. In the aft section, another diesel and/or Stirling AIP engine can be installed. An electrical system may also be extended to supply more consumers.
THE MULTIMISSION PORTAL™ FOR DIVERSE MISSIONS
A key unique feature of the Kockums A26 submarine is the Multimission Portal™ designed to launch and retrieve diverse mission payloads, including those for special operations. The portal is arranged between the 53 cm weapon tubes and has a length of 6 m and diameter of 1.5 m in which up to eight divers can sit ready for a mission in the sea.
At the end of the Multimission Portal™ is an ocean inter- face through which both divers and equipment used in various missions, including UUVs and ROVs, pass while the submarine is hovering or lying on the sea bottom.
Mine coutermeasures can also be launched through the portal. BIBS connections are present for use by divers, if necessary, while waiting to leave the Multimission Portal™. The flexibility of design enables the Multimission Portal™ to be prepared for future payloads of unconventional shape and size such as different types of non-specified UUVs, sensor devices or other bottom-laying devices. Support systems for the portal include those for pressurization and decompression of the portal, supervision and communication.
WEAPONS TO DETER ANY ADVERSARY
The Kockums A26 submarine weapons suite will deter any adversary. The main weapon is the 53 cm heavyweight torpedo, and 40 cm torpedoes and mines can also be carried and launched through the weapon tubes. A total payload of more than fifteen 53 cm weapons is possible. A missile system and a mast-mounted gun can also be integrated with the weapon system. The submarine has a large flexible payload stowage compartment and other types of payload can also be carried externally in dedicated spaces under the deck.
The weapon tubes and associated handling systems are dimensioned to allow various types of weapons to be used, including all existing torpedoes, missiles, mines and UUVs. As the tubes are flooded and drained by gravity, noise is suppressed during preparation for a weapon launch by eliminating the use of pumps or compressed air.
The submarine is equipped with all the necessary equipment onboard to embark and disembark weapons at any harbour or from a service ship at sea. Weapons are embarked through a dedicated hatch in the deck and slid down on the weapon handling rack to the payload storage platform where they are lowered to the horizontal position. Disembarkation follows the reverse route.