In the Baltic Sea, the activity of the naval forces of different countries is always high; the fleets of NATO and Russia are deployed there, and sometimes even Chinese ships come here. Russian and NATO forces vie for operational space, US naval vessels fly at low altitudes over Russian planes, and NATO ships are pursued by Russian vessels. In October 2014, which is considered a turning point in Russia-NATO relations, the Swedish Navy pointed to “alien activity under water,” after which they pursued an underwater intruder in the Baltic waters for a week, but they never caught anyone. The shallow waters of the Baltic, limited in width, complicate operational operations on and under water, but they provide an excellent platform for testing new technologies.
In April 2019, Atlas Elektronik, an electronic systems company for the naval sector and part of the thyssenkrupp Marine Systems (tkMS) technology group, announced the completion of the last stage of testing of its SeaSpider anti-torpedo torpedo (PTT). As Atlas Elektronik said in a statement, "SeaSpider tests have demonstrated the operability of the entire sensor-operator chain of the ship's anti-torpedo protection system with the capabilities of detecting, classifying and localizing torpedoes (OCLT)."
The tests were carried out on the Baltic Sea in the Gulf of Eckernfjord from a research experimental vessel from the technical center of the German Bundeswehr (WTD - Wehrtechnische Dienststelle 71). The prototype SeaSpider was launched from a surface launcher against threats such as the Ture DM2A3 torpedo and an autonomous underwater vehicle based on the Mk 37 torpedo. were used to launch the SeaSpider. The SeaSpider torpedo captured threats and aimed at the nearest point of closest approach. Successful "interception" - the equivalent closest point of closest approach - was confirmed by acoustic and optical means.
Atlas Elektronik added that these tests, as part of a longer testing process, were carried out at the end of 2017; after a comprehensive evaluation of the tests during 2018, the results were approved by the WTD 71 Center.
Torpedo threat
For many years now, the torpedo threat has prevented ships and submarines from walking calmly across the seas. Although only three ships have been sunk by torpedoes in nearly 50 years in combat, the increased torpedo capabilities are forcing NATO fleets to focus on the underwater sphere.
“Right now, we are seeing a growing threat of submarines and torpedoes,” said Torsten Bocentin, director of submarine warfare development at Atlas Elektronik. - The standard reaction to areas with a high probability of using torpedoes is "do not enter". With the growing threat of submarines and torpedoes, which is currently especially relevant in such sea areas as the Baltic Sea or the Persian Gulf, "not to enter" means not to act at all."
Recent advances in technology have helped to improve the capabilities of torpedoes. “We have two big developments,” Bochentin said. "The digital age has finally gotten to torpedoes." Thanks to the advancement of digital intelligence technology, torpedoes are now smart enough to maintain their own tactical picture and classify and respond to contacts. At the same time, simpler torpedoes gained the ability to build their own time-distance diagram using off-the-shelf digital electronics. "Combine with a simple wake guidance device and here you have a torpedo that is jam-proof and does not react to false targets."
“The figure also did not pass by the hydroacoustic stations (GAS),” he continued. - If you look at the physical properties of the GAS, then the ability to perform digital signal processing allows you to fully use the physical potential of the station, as a result, the capabilities of passive sonars have now significantly increased. The capabilities of sonars are currently such that decoys and jammers can interfere with torpedoes, but they will nevertheless hit the target.
Signal processing in digital GAS also fits well with the concept of using anti-torpedo torpedoes. “As a pivotal technology for the SeaSpider project, it is kind of a partial answer to the question, why didn't you do it back in the 1980s? - Bochentin noted. - Digital technology allows for more compact signal processing devices that can be freely programmed to run advanced algorithms. If you compare it with analog electronics or even hybrid analog-digital systems, it becomes clear that only now in the digital age can we embed the capabilities necessary for PTT in such a small form factor."
Technological paradigms
Bochentin argues that the SeaSpider project aims to create two paradigms of subsea technology. “The first is the operational paradigm, when the torpedo threat is unforeseen and. therefore, an unacceptable risk. The second paradigm is the usual way of operating submarine weapons with very high logistics efforts, a very advanced workshop infrastructure and a large number of well-trained personnel required to maintain, transport, adjust and use the weapon system. This is really what we want to change,”he added. The company intends to do this by reducing the cost of engineering, maintenance and logistics, that is, the total cost of ownership. For example, by integrating a jet engine into the SeaSpider torpedo and firing a SeaSpider from a container that serves as both a transport and launch mechanism. "Containerization", as an integrated approach, is designed to "provide the customer with something that is easy to use, which does not make you pay huge amounts for additional systems and services."
Although the concepts and technologies of ATTs have been around for quite some time, Bochentin argues that the tenacious nature of the torpedo threat forces the development of ATTs with special capabilities. “The real problem for the PTT is the wake-guided torpedo, and only with a more specialized system can you cope with it. Atlas has been focusing from the outset on our dedicated solution to counter a wake-guided torpedo.”
The SeaSpider anti-torpedo torpedo is approximately 2 meters long and 0.21 meters in diameter. It consists of 4 compartments: a rear compartment (classified), a jet engine, a compartment with a warhead (if necessary, replaced with a practical warhead) and a guidance compartment, including a sonar-based homing system. Using solid fuel means that the engine has no moving parts; the overpressure created in the combustion chamber is transformed into thrust due to the outflow of gases through the nozzle.
For anti-torpedo protection of submarines (PZP), the homing system, operating in active and passive modes, is supplemented with an intercept function. Although the detection rates for the SeaSpider PTT were not disclosed, the company's background data notes that "the active frequency of the GAS was specially selected for optimal detection of torpedoes with guidance on the wake jet and to eliminate interference with the ship's sensors."Since the main purpose of the PTT is to combat such torpedoes, its active and passive functionality “is specially designed to be effective against torpedoes in the wake weakening zone,” Bochentin said. "In general, higher frequencies increase the likelihood of successfully hitting a torpedo threat."
Fully digital control and guidance functions are based on an advanced semiconductor microprocessor, which includes an inertial measurement unit and is designed specifically to ensure operation on wake torpedoes, and in the case of PZP - for interception. The SeaSpider is also supported by an OCLT sonar mounted on the launch platform.
Although the development of the single torpedo SeaSpider focuses on providing anti-torpedo protection for surface ships, it is also planned to use it in anti-torpedo protection of submarines. The use of both a single torpedo and a container launcher means that once surface ship protection systems appear on the market, the focus will be shifted to submarine anti-torpedo defense and “ideally the customer will be able to reconfigure the submarine or surface ship anti-torpedo defense,” Bochentin said.
“As for the torpedo, we use a remote fuse with a backup shock mode. Tests have shown that a direct strike is a separate option, especially outside the wake, against torpedoes that are not wake-guided. We do not need a direct strike, but we certainly need it as a fallback."
Shallow water testing
A surface ship operating in coastal areas requires capabilities that are optimized for offshore subsea conditions, including shallow water, limited access, uneven bottom, and the effect of proximity to the surface and seabed on UAS performance.
“The Baltic is a shallow sea standard in the scenario of underwater combat operations. To be effective in the foreshore, you have to be the coastal benchmark, if you are not the coastal benchmark, the system will not work there.” Due to the secrecy of the work, Bochentin was unable to provide an explanation of how active and passive sensors cope with coastal conditions. "Any new underwater weapon from Atlas Elektronik sees for the first time real conditions in Eckernfjord at a depth of 20 meters."
A surface ship operating in coastal areas will need to act quickly and at extremely short distances to protect against torpedoes. While previous SeaSpider variants had a starter engine to deliver the torpedo from its launch tube to the point of impact farthest from the ship, tests in the confined waters of the Baltic have highlighted the need to "reduce reaction times and attack distances," Bochintin said. In this regard, two requirements are imposed on the design. First, “the SeaSpider must be brought into the water as quickly as possible close to the protected platform using a downward angled launch tube. Secondly, "a very quick reaction of our propulsion device is needed, so that we can have an instant dynamic ascent and, therefore, can launch a torpedo even in the shallowest areas."
The PTT SeaSpider is aimed at the attacking torpedo using the ship's OCLT sonar. As part of the process of integrating the platform with the anti-torpedo during the tests, special attention was paid to the data transmission channels from the OCLT sonar to the SeaSpider with the possibility of feedback. The OCLT-class system, which is essentially an experimental towed active sonar from Atlas with OCLT functionality, detects, classifies and captures the threat before transmitting data to the SeaSpider shipborne torpedo control unit, which provides it with a set of parameters based on this data and launches. This is what we have successfully completed in the now completed series of tests."
There are three options for launching the SeaSpider PTT from the carrier platform: using a local control panel (also known as a torpedo launcher computer) located near the launch frame or mounted on it; either from the control room using a separate console or by downloading the software to an existing multifunction console. As for the console concepts in the control room, “most likely, any standard console will not be a separate console only for the SeaSpider, but will be an integral part of an integrated anti-torpedo defense,” Bochentin said. This console also includes the OCLT sonar control system.
Although the SeaSpider torpedo itself is a homing weapon, Atlas is interested in developing an OCLT-class system capable of monitoring target acquisition so that when the OCLT sonar provides reliable data about it, “we could follow the 'fire-aim-fire' philosophy. "If the probability of hitting the target during the initial capture is assessed negatively."
When launched, pressurized air in the container pushes the SeaSpider torpedo downward at an angle. The launch container itself is placed on the launch frame (ideally permanently fixed to the carrier platform), through which power supply and data transmission are carried out.
One of the priorities of the SeaSpider project is the development of a cassette launch principle. The ready-to-launch cluster-type combat vehicle accelerates deployment and simplifies logistics. The goal of the company is to certify the entire SeaSpider product with a launch canister. Launch containers are designed to be transported in standard shipping containers.
The development of a combat-ready torpedo using the cluster principle and the launch frame also means that the number of torpedoes on a ship can change based on need. On larger platforms, “for example, cruisers and destroyers, you will need to distribute the launchers along the length of the ship, on the port and starboard sides,” Bochentin said. Smaller ships with shorter cruising range need fewer launchers. However, the minimum number of installations is determined in the aggregate by such characteristics as, for example, the size of the ship, maneuverability and cruising range.
Anti-torpedo torpedo tests
In the sea trials that ended in 2018, "the SeaSpider anti-torpedo was launched from a fixed platform at the torpedoes of a conventional enemy, which actually simulated a dynamic scenario."
The next test cycles, which will take place over the next few years, as the initial combat readiness is scheduled for 2023-2024, will include testing of the wake guidance system, when a SeaSpider is fired from a moving platform at a torpedo operating in the wake of that platform. This, according to Bochintin, "will be a major milestone in the program." The next stage of testing should end with the release of the product to the market.
SeaSpider torpedo readiness
The main step towards the planned readiness for operation in 2023-2024 will be the appearance of the launch customer or customers by the date planned in this schedule. While several NATO fleets, along with the NATO Industry Advisory Council, are evaluating the requirements, capabilities and options for anti-torpedo protection of surface ships, Bochentin did not name any customers with whom the company works. However, the German armed forces are currently involved in the development and testing of an anti-torpedo torpedo.
The most important role of the launch customer is to facilitate the adoption of weapons systems. “The industry itself cannot do some things. We need a fleet as a customer with its powerful research structures to complete the qualification and certification of the systems being developed."
In order to strengthen the cooperation with a potential start-up customer, Atlas Elektronik decided - with the support of the parent company tkMS - to continue proactive development. Atlas has partnered with Canadian company Magellan Aerospace under a direct agreement to develop, certify and qualify explosives for mass production, as well as leverage Magellan's extensive experience in jet engine technology.
"An important milestone here is the qualification and certification of the explosive." While technology development and testing has been carried out to date, the serial version of the standard high-explosive charge requires full certification in accordance with NATO standards (STANAG) for low-sensitivity explosives; all production of this variant is part of the certification process. The tremendous effort and lengthy time it takes to obtain such certification means that explosive development is “a critical milestone” in the development of SeaSpider's capabilities. A key part of the development process in 2019 will be the collaboration with Magellan and the start of testing explosive components.
Contacts between the two companies were confirmed in a press release issued in April 2019. It states that "Magellan will lead the design and development of the SeaSpider torpedo jet engine and warhead, including design, testing, fabrication and product verification."
Bochentin noted that the technologies developed under the SeaSpider program have mostly reached readiness level 6 (technology demonstration), and some elements are close to level 7 (subsystem development). Here the company focuses on the development of special components, for example, sonar algorithms.
Another important element in achieving initial capabilities, and thus another area of focus for 2019, is preparation for simulating the capabilities of the SeaSpider anti-torpedo torpedo. “You can't just test every variable using the PTT, so you can talk about a two-pronged process,” Bochentin said. “On the one hand, you want to have sea test data that supports the simulations. On the other hand, you want to have capabilities that allow you to go beyond what you experienced at sea with this simulation."
The need for anti-torpedo protection for NATO fleets is growing steadily as they face threats of torpedo attacks in the North Atlantic, the Baltic Sea and the Eastern Mediterranean.
The NATO command publicly notes the activity of Russian submarines. Perhaps the risks here are not just theoretical. For example, in April 2018, British media reported on a Russian Kilo-class diesel-electric submarine that was getting too close to American, British and French forces in preparation for attacks on Syria.
