frigate MEASURANT: New capabilities of MW RP in ZOP

Multitasking frigates built under the MEASURANT programme in the coming years will replace used Oliver Hazard Perry ships. One of the tasks that the predecessors will take over is the Battle of the Submarine (ZOP), which is the main destination area.ORP Gen. K. PulaskiandORP Gen. T. Kościuszko.

Both ex-American ships have made an important contribution to the increase of potential of the ZOP of the Polish Ministry of Foreign Affairs and beyond taking over the tasks of predecessors, one of the objectives of the MEASURANT programme is to carry out the next step forward. Among the operational requirements faced by new frigates in the ZOP area is the achievement of the ability to neutralise threats from present and evolving underwater threats, in the operational areas of the Polish Navy. This means that we need to create the potential to successfully confront a difficult opponent, operating in an additional difficult environment.

Systems of the submarine department, with which future from 2000 to 2002,ORP Gen. K. PulaskiandORP Gen. T. Kościuszko, in a very general definition, they were not fully suited to the conditions under which the tasks of the ZOP must be measured by the MW of the Republic of Poland. This resulted, among other things, in replacing the main weapons of the ZOP on these ships (and in later years also in naval aviation) with MU-90 torpedoes. Another important step for the capabilities of the ZOP was the modernization of the passive towed station AN/SQR-19 TACTAS.

This resulted in an increase in the efficiency of the search for submarines, recorded at the stage of development and sea trials, and later also during NATO operations and exercises. The knowledge and experience gained, among other things, today not only allowed a better understanding of the changing nature of the activities of the ZOP, but also identified needs for the future development of forces. The decision to start building new ships gave the opportunity to make use of this knowledge by choosing tools that are optimal for needs.

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Passive hydroacoustic systems (such as the mentioned, modernized AN/SQR-19PG station) were the main underwater surveillance tool during the Cold War. Today, passive detection remains one of the tools of the ZOP, but its role has clearly given way to the next generation of LFAS (Low-Frequency Active Sonar) sonars. This is due to progress in the silence of submarines and the difficulty in finding them, especially in areas where noise-trace activities are unfavourable.

A Closer Future

As withORP Gen. K. PulaskiandORP Gen. T. Kościuszko, the new frigates will be equipped with two hydroacoustic stations: a hull (fore pear) and a towed variable depth. Both of these sensors, like most of the other fighting components of THE MEAT, come from Thales, which significantly reduces the risks associated with the integration of the entire combat system.

Thales BLUE HUNTER station (KINGKLIP Mk2) is a mid-frequency fuselage sonar provided for corvette and frigate class units. Sensors of this group are the minimum necessary for submarines to engage them in the activities of the ZOP. In addition to the active search for submarines (essential working regime), passive monitoring is conducted in parallel, to warn about approaching torpedo ships.

The Thales CAPTAS-2 towed station belonging to the subcategory of active low-frequency sonars LFAS is an element determining as far as possible the surveillance of underwater MEASURERS and placing these ships higher than the units equipped with hull sonar itself. Sonar was towed and will remain a potential-determining sensor, and consequently, the location of its host in the SOP tactics.

The low frequency active capacity (0.9 – 2.1 kHz) also represents a significant potential (far range) for future capabilities of ships in multi-static networks. The CAPTAS-2 antenna assembly consists of an active element (low frequency pulse sources) placed in a stabilized circuit, to which is connected a passive linear antenna containing modules for receiving reflected pulses (echo-tracking) and passive surveillance (shumo-tracking). The antenna assembly thus folded retains very good control over maintaining its immersion at the desired depth, which is an important attribute – especially in shallow waters.

CAPTAS-2 belongs to the CAPTAS familySonar) of scaled construction. The range of sensors offered by the company allows for their selection in terms of adaptation to operating conditions and host. The numbering used in the name corresponds to the number of transducer rings that are the source of low frequency pulses.

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In addition to specially dedicated systems for frigate MEASURANT, it is also worth paying attention to aeronautical acoustic systems. Their importance is growing in the context of the future activities of these ships combined with the new generation of maritime aviation, which is already entering service. A key tool in the search for submarines for AW-101 helicopters are Thales FLASH exit stations, which may also be equipped with new on-board helicopters acquired under the Condor program. Additional strengthening of these abilities are radio-hydroacoustic buoys (PRHA, colloquially referred to as "sonoids"), including those classified as "new generation". All these sensors have the potential for future multi-static actions.

In the context of submarine effectors, ships will also receive two systems of submarine effectors. The first ones are well known, being already 20 years on the arming of the naval forces of the Polish Navy, light torpedoes of the MU-90 type supplied by the French-Italian EuroTorp consortium. The MU-90 is a third generation torpedo and thanks to EuroTorp's modernization of its components, it remains at the forefront of the most modern in its category.

The manufacturer is currently conducting development work on the new MU-90HK combat version, which will be a dual-function effector. A new version of torpedo, analogous to the standard MU-90TC, will serve to combat submarines, but it will also be possible to use it as counter-torpedo function. The modifications introduced will not affect the need for changes in the torpedo launcher or firing net, resulting in a fire unit dedicated to the ship itself (except for the onboard helicopter) of these torpedoes securing two capabilities with one effector.

The second of the effectors is Terma's C-Guard virtual target launcher system. The system consists of a set of motionless 135 mm mortar launchers included in the central firing network system. The C-Guard is mainly associated with an element of the electronic combat system and the upper half-sphere area, but in a wide range fired from its apparent targets launchers there are also missiles for SSTD (Surface Ship Torpedo Defence) SOFTKILL defence.

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The idea of using these missiles is to disrupt and interrupt the torpedo guidance process on your own ship and/or your protected unit and then leave the torpedo danger zone as quickly as possible. The sources of the high risk of an enemy torpedo in the vicinity of the forces, are its distant reach and logic in the self-conducting system, which will attempt to regain contact with the target. This means that exiting the occupied zone can be a large amount of disruptors.

The growing demand for counter-torped SOFTKILL effects, and in recent years also HARDKILL, is one of the increasing trends in the world. This is due to the scale of the threat the main submarines carry, i.e. heavy torpedoes, having a range advantage and a very high-force warhead (one torpedo is able to sink or at least completely disable the ship from operation). Due to how difficult and high-risk the anti-torped defense process is, the combination of SOFTKILL and HARDKILL effects is starting to be seen as a necessity.

The future of the ZOP

The frigate OF THE MEASURANT described above presents itself very well in relation to today's needs and operating conditions. Selected components (sensors and effectors) are not always the ones with the greatest potential among the options available, but not the selection criteria. The indication of optimal solutions that can be fully exploited was one of the objectives of the analysis undertaken in the initial phases of the programme. However, the sword did not stop at the "today" perspective, opening the way for the future of these ships. In the field of the ODP, two further areas of further development are visible:

• multi-static operations,
• integration of unmanned platforms.

The search for submarines using multi-static detection, which can be referred to as "collective detection", is currently a loud slogan referring to world-wide development programs. This action consists of integrating several distributed sensors (active and passive) into a common surveillance system, so that as participating elements in it both contribute in the form of their own impulses and/or participate in the detection of echoes from other sources of emissions (included in the active sensors system).

For accuracy, acoustic multi-static systems have already reached maturity and are operationally used within a single platform. An example is a marine patrol aircraft, operating multi-statically with active and passive radio-hydroacoustic buoys. The challenge is the next step, which is to combine such a system of "collective detection" of separate platforms (e.g. a ship with a ZOP helicopter) with their sensors (or sensors under their control – PRHA).

The first of these examples is simpler because, apart from the ability of the sound processor itself on the aircraft, it does not require additional coordination tools, and the entire acoustic analysis process, despite the scattering of active and passive elements (PRHA) takes place in one place (on board the aircraft). In the second case, synchronization of this process takes place between several acoustic systems on different platforms (cross-platform multi-static network) for which an additional network dedicated to this process is needed.

^{Comparison of surveillance zones in the group of units of the ZOP operating mono-static (left), with the same team, operating additionally in the multi-static network (right)}

The advantage of such a network is, above all, to increase surveillance tightness and to unify the acoustic image in one consistent for all the units involved. However, new capabilities also entail further needs, and in this case it is primarily a tool for planning and controlling the course of the ZOP mission, which will allow optimal dislocation of units.

One of the solutions that are being developed today, which in the future will be able to reach for these capabilities, is that of Thales, the BLUE SCAN system. It is a system, integrating acoustic sensors of units conducting search for submarines and connected in a common network. BLUE SCAN synchronizes the performance of sensors (cycles and emission parameters) on the network and merges the acoustic image.

The BLUE SCAN system and similar solutions will increase the efficiency of submarine search and reduce the response time of ZOP units. The ability to operate in a multi-static network will soon become one of the main measures of the potential of the ZOP.

The second of these issues, namely the further future of the development of THE MEASURER, are unmanned platforms, whose participation in maritime activities has been increasing rapidly in recent years. In order to keep up with the evolution seen today, the project takes into account the potential for future integration of unmanned systems. Ships will have space for task modules and the necessary infrastructure to ensure that the integration process, at any level would not be, does not require deep modifications to the combat system or interference with the platform structure.

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The use of unmanned platforms in ZOP operations is one of the very dynamic directions arising today, as in other areas of combat activities, from their growing capacity (e.g. thanks to new compact sensors) and relatively low cost compared to manned platforms. A particular interest and a high level of development can be seen today among the many air platforms programmes planned for the ship's activities. The replacement of crewed helicopters and sea patrol aircraft of the ZOP with unmanned systems is not the aim of these initiatives, but they can play an important role in expanding the range of activities in extensive operating theatres or restricted access or high risk areas.

The range of launch masses, already tested in the world's marine forces, of organic structures (i.e. capable of being based on a ship) is very large, particularly visible in the category of centrifuges. Unfortunately, the classification is still unstandardized, but a wide range of solutions that can be seen today can be shared within three contractual aircraft groups: light weights of about 200 kg (e.g. Shiebel S-100), averages of about 600-800 kg (e.g. Airbus VSR-700), up to 3000 kg (Northrop Grumman MQ-8).

^{Light Air Ship Shiebel S-100, which is currently undergoing testing of variants dedicated to the ZOP: PRHA drop unit (left) and PRHA acoustic data retranslator (right)}

In addition to the air platforms, the MEASURER will also provide space for light-free water, and when needed also underwater (after adjustment for lowering and taking from water). The Arrowhead 140 project, on the basis of which the Sword is built, provides for as many as 4 spaces for shipboats, so adapting for example one of them to board a similar size of unmanned craft will be possible, not necessarily at the expense of other needs.

^{Programs from various fields often include adaptation modules for base on board ships, an example is the ACRIMS system developed by Atlas Elektronik UK}

The frigate MEASURANTs were not designed for the tasks of the ZOP as their priority mission, as was the case with the British T26. Polish ships will not achieve such a strict level of silence, but, on the other hand, operations in high noise and difficult propagation conditions are also in part natural masking, which affects the threshold of this requirement. As a multitasking vessel, the sword is intended to maintain a balanced proportion to the operational needs of all combat spheres, which will also be achieved in the ZOP, giving a significant increase in capabilities of the Polish Navy and NATO task forces during allied operations.

Written by Kamil Sadowski