Weapon system design - a key factor for superior submarine capabilities in the modern battlespace

Through evolutionary and modular design, Saab’s submarines offer a flexible configuration, tailored for the various needs of navies around the world. This flexibility, allow for easy upgrades and modifications to adapt to evolving mission requirements, making the submarine future-proof. Equipment installations can be easily accessed for maintenance and upgrades at any point in the submarine's lifecycle.

Expeditionary and blue water submarines rely on autonomy and engagement from a distance where surveillance ability, endurance, speed, evasiveness, stealth and high versatility in engagement capabilities is important for mission success. Effective weapon launch systems on submarines offer exceptional operational flexibility and enables submarines to carry a diverse array of weapon types, including anti-ship missiles, land-attack missiles,torpedoes and mines, all in the same launch system. This versatility allows submarines to adapt quickly to changing mission requirements without the need for extensive reconfiguration.

To enable this flexibility and to achieve launch capability across the whole operating depth and speed range of the submarine, a pumped water system was adopted by the US many decades ago. To be compatible with US weapon system such as the Mk48 Mod 7 and in particular the Tomahawk Land Attack Missile (TLAM), the submarine must have a compatible pumped water launch system.

However not all pumped water systems are the same. Having used a water ram (or ram/piston pump) system for many decades, the US recognised the limitations of a fixed stroke water ram launch systems (lack of flexibility due to the fixed stroke and significant negative impact (due to both noise/signature and time delay) of the inevitable rapid water ram return stroke for salvo firing). Moreover, a water ram solution inevitably leads to more equipment and control systems in the harsh environment outside of the pressure hull which cannot be easily maintained, potentially leading to poor reliability/availability. Hence the US moved to compact rotary pumps in the early 1980's. This technology advancement was then adopted in ocean going SSK submarines such as Walrus, Upholder (now Victoria), and Collins.

The integration of complex weapon systems requires the exchange of sensitive information authorised for release at Government-to-Government level. Having integrated these US weapons, Saab and its suppliers have already established the required protocols for information handling, on previous projects, thus reducing schedule risk to the project. Such information will include details of how the weapon is to be initialised and its associated required dynamic behaviour as it is launched from the tube and transitions through to achieve full vehicle trajectory control ahead of the submarine. These complex weapons exploit the flexibility and control achievable with a rotary pump solution to ensure the correct dynamics are achieved to satisfy launch initiation. Moreover, the unusual configuration of the TLAM, requiring both additional energy, specific launch profile requirements and tube design flow-optimized for the specific version of TLAM e.g., Block III, IV or V, to achieve launch success. Launch system offered by Saab has demonstrated its ability to successfully launch TLAM.

Saab offers a weapon and combat system suite based on proven designs from suppliers that have their systems operational on submarines, providing confidence, great knowledge and extensive experience. Saab has a long history of collaborating on the integration of combat system, weapon systems and weapon launch system into a successful harmonized and effective solution.

Combat Management System

An integrated Combat Management System (CMS) is truly the heart of a naval submarine and equally important as the weapon tubes and discharge solutions for a successful weapon launch.  Composed of both hardware and software, an integrated Combat Management System collates vital data and transforms it into a readily viewable format to support execution of the crew’s missions and the operational objectives for a Navy at sea. An integrated CMS supports the most important functions for the submarine commander where the fastest decision loop from detection to engagement prevails. A submarine that falls short of a fully integrated CMS may be slower to act as the operator may need to switch between systems and/or consoles to engage after detection. 

For the Expeditionary submarine segment (C71), Saab can offer a CMS that allows for deeper integration with all the submarines combat systems such as acoustic sensors, optronics, navigation, and electronic support measures.

This CMS includes a weapon control manager that has been developed with an emphasis on simple upgradeable capability insertion via modular hardware and software components, that supports the firing of Mk48 torpedoes.

In submarine design, it is important to incorporate the ability to meet the constantly developing threats in the underwater domain and the demand for new capabilities and flexibility of the platforms. Considering the tactical weapon suite on board the Expeditionary submarine, the need to adapt for new capabilities and provide versatility to launch different weapons and payloads throughout the life of the submarine is essential.

Success factor

The success factor behind pushing the performance of the Expeditionary submarine’s ability to make the most of the weapon’s unique capabilities. This requires deep knowledge and considerable experience in proven designs and the development of a tailored submarine in collaboration with the weapon launch and CMS providers.