News

2017-04-02

Sweden Dominates the Seas with The A26 Disruptor

Strategically important in a nation’s defence, submarines are designed to operate for decades in challenging environments, while remaining adaptable to the tide of technology and future threats.

The Swedish Navy's A26 type submarine, designed and built by Saab, is the world’s most modern submarine programme. It is a next-generation submarine with flexible design, adaptable for both littoral operations and ocean-going capabilities. With a displacement of around 2000 tonnes, long submerged endurance and a highly-flexible payload capacity, the A26 will be a formidable defence asset.

Saab will construct, verify and deliver two new Type A26 submarines for the Swedish Navy to a total order value of SEK7.6 billion, between 2022 and 2024.

Håkan Buskhe, President and CEO of Saab, said the company is “exploring export opportunities to provide complete submarine systems to a select number of countries, plus subsystems across the wider market.”

The submarines will be powered by conventional diesel-electric propulsion machinery and equipped with the Kockums Stirling AIP (air-independent propulsion) system.

“The A26 will be a unique, high-tech submarine with proven modular design, which gives the platform a high level of availability at a low life-cycle cost. The submarine will have long-endurance submerged performance and excellent manoeuvrability in all waters. Safety is paramount, and A26 will be highly survivable thanks to modern underwater stealth technology and a unique heritage of shock resistant design,” said Gunilla Fransson, head of Saab Security and Defence Solutions.

According to Per Nilson, program manager for A26, the next generation of submarines will be a step further yet again:

Intelligence Gathering

“It will be much quieter, the sensors will be more advanced - detecting and documenting everything that goes on in the sea - and there will be a number of new capabilities, such as the multi-mission portal in the bow for hosting divers and small manned or unmanned vehicles. It will be a first-class intelligence-gathering platform” he said.

The A26 is robust, silent and very technology-intensive, but there’s more. “We have several advantages”, says Per Nilson. “Our production method with optimized workflow, proven modular design that facilitates production at any shipyard, adaptation to customers’ requirements, efficient through-life support and a high level of availability”

The A26 submarines will be very hard to detect, nearly invisible. The signature characteristics of the submarine have been optimised and balanced from all perspectives; acoustic, heat, hydrodynamics, to mention a few.

Construction is very rigid and shock resistant, in order to withstand impacts from mines and other underwater weapons. Like all submarines built by Saab, A26 will be shock tested in real life before handover, a quality assurance that increases survivability of both submarine and crew.

Air-Independent Propulsion

The Kockums Stirling air-independent propulsion (AIP) system allows A26 submarines to stay submerged for several weeks undetected. The days when submarines hunted alone at sea are over. Today submarines need to communicate with other units to perform highly strategic operations; therefore network connectivity is a prioritised and intelligent functionality on the A26.

The Way Ahead

Saab’s A26 uses the latest stealth technology and advanced tactical communication to integrate communications with those of other defence forces and civilian agencies. Operational flexibility, together with a comprehensive weapons suite, enables it to carry out a wide variety of missions.

It is suitable for maritime security operations, Intelligence operations, including acoustic, visual, electronic and communication intelligence; covert mine countermeasure operations, including mine searching and clearance using unmanned underwater vehicles, and mine-laying in covert mode.

Special operations such as carrying, deploying and retrieving special forces along with equipment and underwater vehicles are another A26 capability.

On top of this, the A26 can conduct anti-submarine warfare by searching, locating and classifying approaching and attacking submarines, and by countering other submarines. It is equipped to perform anti-surface warfare where both internal sensor data and/or external target information is used, and underwater work such as manipulating, deploying, retrieving or destroying underwater objects and installations.

Securing Littoral Supremacy

The centre of attention for naval operations has shifted from blue water to the littoral zones. 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, a submarine's to lie motionless on the ocean floor, or ‘bottom out’, makes it almost impossible to find.

Submarine operations in the extreme littorals are 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.

The A26, with superior GHOST (Genuine HOlistic STealth) properties and AIP, is a valuable asset in securing total control in the extreme littoral zones.

Securing Blue Water Capability

Not only does Saab’s A26 submarine have excellent transit capability, but it can also operate in big oceans because of its long transit range and extensive endurance. As well as a high snorting speed and deep diving ability, it offers high seakeeping performance, and, most importantly, excellent crew comfort.

Optimised Ghost For Virtual Invisibility

Sweden's Genuine HOlistic STealth (GHOST) technology makes the A26 effectively undetectable, as all its signatures are even lower than those of the Kockums Gotland Class submarine.

Sweden has long experience in designing very silent submarines. On the A26, extensive rubber mountings and baffles are used to minimise 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.

The Sounds Of Silence

To become invisible, further ways of keeping silent are exploited by the A26. The target strength of the A26 submarine is minimal because of the vessel’s unique hull shape and fin design; sonar and equipment accommodation, and a new type of surface acoustic absorption or reflection coatings. This highly optimised 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, 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 minimise electrical signatures without compromising the corrosion protection of the submarine.

Enhanced AIP Performance

The A26 is dimensioned for nominal missions of several weeks. The AIP technology allows it to stay fully submerged for long periods of time during a mission.

The Stirling AIP system is the main propulsion system, used for all submerged operations at patrol speed. It is extremely quiet and does not create any thermal (IR) signature. The diesel engines are used only for long distance transit at medium speed in either a surfaced or snorting condition.

All Swedish submarines today have Stirling AIP. It is compact, modular and manageable, important spare parts can be stored on board, and the system can be maintained and repaired in situ by crew members, even while in operation during a mission.

The AIP system burns a mixture of gasified pure industrial liquid oxygen (LOX) and diesel fuel. The same low-sulphur diesel is used for both the diesel and Stirling engines. Thus both LOX and diesel enable cost-effective energy production and simple logistics.

A26 Modularity

A key benefit in the design of the submarine is its modularity, which provides an amazing degree of operational flexibility, future-proofs the vessel and contributes significantly to cost-effective construction and assembly.

Combat System Infrastructure

In order to facilitate secure system integration, future upgrading and expansion, as well as reduce costs, all parts of the Combat System are interconnected through the combat system infrastructure (CSIS).

This is the backbone of all information systems in the combat system, comprising an open architecture distributed system that integrates combat subsystems in a secure way, according to Saab's IT security architecture. To cut lead times and costs, the CSIS is mainly based on commercial off-the-shelf (COTS) products, technologies and standards, adapted and/or applied to naval military applications.

All applicable subsystems are interconnected through the CSIS, and operated from common multifunctional consoles (MFCs). CSIS access points throughout the submarine enable easy connection for a large number of additional subsystems, MFCs, workstations and laptops.

Decentralised Combat Management

A Saab combat management system (CMS) has been specially developed for this submarine. Instead of a central system to which all other systems are integrated, the CMS is a subsystem linked to the CSIS which communicates using open standards. This allows integrated systems, including the CMS, to be individually upgraded or exchanged, thereby greatly reducing project risks typically found with large, complex and highly integrated systems.

The CMS allows high-performance data exchange via the CSIS with other systems like sonar, Electronic Support Measures (ESM), weapon interface systems and the vessel control system. Like most other subsystems connected to the CSIS, the CMS can be operated from any MFC in the submarine.

Minimising Life Cycle Costs

Saab has taken numerous measures to minimise life cycle costs:

The modular concept is production-friendly by allowing preoutfitted platforms to be constructed off site and delivered when required.
Modularity allows continuous, straightforward adaptation or updating of systems and equipment to allow future-proofing.
A high degree of automation of all management and control systems means smaller crew required.
Saab’s Integrated Logistics Support (ILS) extends the operational lifetime of the submarine. A condition-based maintenance concept ensures not everything needs to be replaced at the same time. This also maximises submarine availability.
Advanced life cycle cost analysis is conducted to ensure low operating and maintenance costs.
Saab uses COTS components instead of MIL-standard parts where possible to reduce repair costs and simplify work.
Onboard maintenance of the Stirling AIP engines can be performed by the crew.
Replenishment at sea can be carried out, including for the Stirling AIP system and torpedoes.
The A26 submarine is designed and developed from an economical perspective to provide a very cost-effective investment, when considering the decades during which it will be operational.