First Guided Firing Test of AKYA National Heavyweight Torpedo Against Mock Surface Target Successfully Carried Out

Issue 104

The first guided firing test against a mock target within the scope of the AKYA National Heavyweight Torpedo (HWT) Project was successfully carried out on January 20, 2021, before its expected deliveries that are scheduled to take place in 2021.  The project was launched on May 8, 2009, to meet the 533mm (21 inches) modern heavyweight torpedo requirements of the Turkish Naval Forces Command (TNFC) through national means and capabilities.  According to the information I received, during the firing test carried out with the AKYA Heavyweight Training Exercise Torpedo (without a live warhead) at the Submarine Training Range of the Turkish Navy located in the Gulf of İzmit in Marmara Sea, the simulated surface target was successfully hit and sunk.  

On January 25, 2021, the Ministry of National Defense shared a short video on its official social media account stating, "Our TCG Gür Submarine successfully fired the AKYA Training Torpedo in the Sea of Marmara." In the footage, which was shot with the camera placed on the submarine's nose, the launch of the AKYA Heavyweight Training Exercise Torpedo from the submarine is clearly seen. Shortly after leaving the tube, it appears as if the reinforced fiber-optic guidance cable (that hangs out of the central hub of counter-rotating propellers at the propulsion section), which provides two-way instant communication between the launching submarine and the torpedo, is breaking (because it seems that the cable that should have been stretched suddenly comes loose), but according to the information I have obtained, the guidance cable continues to be released in the rest of the footage. Another point that draws attention in the shared video is that the view distance in the Gulf of İzmit, where the jellyfish infestation is experienced, has decreased considerably due to the pollution. Thus, it cannot be seen whether the AKYA HWT has performed the expected maneuvers after leaving the tube during the launch test, which I believe was conducted at a depth of 40-60 meters. Usually, after launch HWTs make a short dive to stay under the submarine so the submarine does not run into the guidance cable, potentially tangling it around the submarine’s sail and propeller. This maneuver can be clearly seen after the DM2A4 SeeHecht HWT launch conducted from a GÜR Class submarine within the scope of the Beyaz Fırtına (White Storm) 2016 Naval Exercise held on May 16-28, 2016. The Turkish Naval Forces had previously launched DM2A4 Training Torpedoes from the TCG Gür and TCG Burakreis Submarines in the Mediterranean on April 10, 2020, and both DM2A4 and Mk46 REXTORP Exercise Torpedoes in the İzmir maritime zone on September 19, 2020, for training purposes. 

Under normal conditions, command wire or fiber-optic cable guided Heavyweight Torpedoes (HWT) can receive the necessary guidance commands from the launching submarine via the guidance wire/cable until the moment of impact. A command wire or fiber-optic cable that reels out from behind the HWT establishes a data link with the submarine’s fire control system (FCS). Fiber-optic cable is a more suitable solution than copper wire since it can both float and offer a wider bandwidth (typically 10 Mbit/s, which allows a much larger volume of information to be transmitted between the torpedo and the submarine). Guidance commands are sent to the torpedo via one-way copper wire in old generation HWTs such as Mk24 Mod 2 TigerFish and via two-way high data capacity fiber-optic cable in new generation HWTs such as DM2A4, SpearFish, and Mk48 Mod 6/7AT. The torpedo can also act as an outside sensor by sending the acoustic signatures it obtains with its sonar to the launching submarine via a two-way fiber-optic cable. The reinforced fiber-optic cable (the guidance wire/cable between the torpedo and submarine is longer than the torpedo's maximum range), which is specially designed to the maneuverability and speed of the torpedo, allows making necessary corrections to critical information such as the position and distance of the target, kill box (the digital boundaries where engagement will take place - designed to prevent the torpedo from attacking the submarine or any other target outside the designated area), or the route and depth to be followed after the torpedo launch. Thus, the possibility of missing the target with the fire and forget type weapon systems is minimized (in emergency engagements where the necessary pre-settings cannot be made, fire and forget type torpedoes may miss the target due to missing or incorrect target coordinate/distance information). However, as the fiber-optic cable is very thin (300 micrometers thick in DM2A4), it can sometimes break, the torpedo may accidentally cut its guiding wire/cable with its propeller while dealing with fake targets (acoustic decoy or jammer) launched from the target ship/submarine, or the submarine itself may drop the wire/cable as it needs to evade the light/heavy torpedoes or depth charges from the target ship/submarine in real combat conditions.

Therefore, in a typical attack scenario, the torpedo is guided to a certain distance from the target by the CMS/passive sonar equipment on the launching submarine that launched it via copper wire or fiber-optic cable. Then, at a certain distance, the torpedo first activates its passive sonar, and while traveling at low speed, it secretly scans the target area (so it can capture acoustic signatures with its sonar more efficiently in the target area). If a target is detected in passive scanning mode, the torpedo attacks the target using the element of surprise (In passive mode, the target ship can detect an incoming torpedo only from a very short distance, but it will be too late). If it is not possible to detect a target in passive scanning mode, the torpedo classifies its prey with the help of active sonar in the terminal phase and determines the target's exact position, speed, depth, and route. Then, it releases the cable and autonomously attacks the target at high speed. Typically, active sonars onboard the HWTs have a range of 5 to 10 km but are usually activated at a shorter distance to the target, as it takes approximately 6 minutes for a torpedo with a speed of 50 knots to arrive at the target ship from 10 km distance. This gives the target ship, which can easily detect the active sonar ping, enough time to perform an avoidance maneuver. Modern torpedoes can distinguish between the target and the background sea echo thanks to their Target Motion Analysis (TMA) capability and advanced guidance and control algorithms running on the internal microprocessor/computer. Additionally, they can identify false targets autonomously. Modern heavyweight torpedoes such as the DM2A4 SeeHecht and SpearFish have built-in TMA capability as well as re-attack capability.

Initially, I thought that the AKYA Heavyweight Torpedo with a live warhead would be test-fired from the GÜR Class TCG Gür Submarine on January 20 off the coast of Bartın and Kastamonu considering NAVTEX issued on January 15, 2021. However, I later learned that the launch test was carried out at the Submarine Training Field in the Gulf of Izmit, and on its official social media account, the Ministry of National Defense stated that the test was carried out in the Sea of Marmara. We can say that if a war shot (with live warhead and acoustic head) AKYA Heavyweight Torpedo, that is scheduled to be tested against a real surface target during coming months in 2021, would be successful then the serial production phase will receive the green light and the delivery process will be started immediately.

In fact, I was expecting the first firing test of the AKYA National Heavyweight Torpedo with a live warhead to be conducted from the first PREVEZE Class submarine prototype modernized with MÜREN CMS because this is what I heard during the IDEF '19 Fair. Furthermore, on January 21, 2021, TÜBİTAK President Prof. Dr. Hasan MANDAL confirmed that the MÜREN CMS became operational on a PREVEZE Class Submarine. MANDAL said, "We received great news today. The MÜREN-PREVEZE CMS has entered service with the Turkish Navy. In other words, it is being used in a real operational environment."

I think that the Turkish Naval Forces preferred the TCG GÜR Submarine equipped with Atlas Electronics product ISUS-90/33 CMS instead of the PREVEZE Class equipped with MÜREN CMS for test-firing of AKYA HWT because both the torpedo tubes and the Combat Management System of TCG GÜR are compatible with the new generation DM2A4 Heavyweight Torpedo, which has fiber-optic cable guidance like AKYA. According to open sources, the torpedo tubes of GÜR Class Submarines were modified to launch the DM2A4 Heavyweight Torpedo, which is 6.9m long, weighs 1,670kg, and has four battery modules ensuring a range of 50km with 40 knots, 38km with 55 knots, and approximately 100km with a low speed. The PREVEZE Class, on the other hand, uses the Mk24 Mod 2 TigerFish Heavyweight Torpedo with a length of 6.46m and a weight of 1,551kg and can reach 12,000 yards (10.973m) at 40kts. The first launch test with the AKYA National Heavyweight Torpedo prototype without the warhead and active/passive sonar was successfully carried out from a 533mm torpedo tube placed on an underwater test platform in the Sea of Marmara on July 11, 2013, and since then more than ten firing tests in different configurations were carried out with AKYA HWT prototypes, which have not been publicly disclosed yet.

The last launch test shared with the public under the AKYA National HWT Development Program was performed on December 20, 2019. Announced to the public for the first time during the 2019 Annual Evaluation Meeting held at the Beştepe National Congress and Culture Center on January 16, 2020, by President Recep Tayyip ERDOĞAN, the AKYA National HWT with a live acoustic seeker (active/passive sonar) was successfully launched from a detailed 533mm torpedo tube replica installed to an underwater test platform at a depth of 40m. Smart acoustic buoys from Koç Information and Defence Technologies (KBS - Koç Bilgi ve Savunma Teknolojileri) were used to monitor the qualification test carried out at the Torpedo Test Range established in the Marmara Sea. Until indigenously developed live acoustic seekers become operational, a dummy seeker head was used during the launch tests of AKYA HWT for the purpose of weight simulation.  

The AKYA National HWT Development Program Phase-1 (Development Phase) Contract worth EUR24 million was signed between the Presidency of Defense Industries (SSB) and the Main Contractor Roketsan on May 8, 2009. Within the scope of the AKYA Phase-I Project, in which Turkish Naval Research Center Command (TNRCC/ARMERKOM) also took part in the design process, activities were carried out mainly to determine the hydrodynamic form of the torpedo as well as the design and production of certain subsystems. In addition, a separate R&D study was conducted on the exercise version battery. Under the AKYA National Heavyweight Torpedo Program, Roketsan will develop the warhead and guidance system, Meteksan Defence will develop the sonar transducer arrays (sonar wet end), and KBS will develop the Wake Sensors, Torpedo Test Range Underwater Detection and Positioning System, Acoustic Signal Generators, and the Underwater Acoustic Models (to verify the systems and software to be developed under the program). Havelsan also took part in the project. 

The first phase of the AKYA Program was completed before the planned schedule and below the expected cost under Turkish Naval Forces Command's responsibility for its design and performance, and successful launch tests were carried out during this period. The first prototype torpedo was developed nationally by the Main Contractor Roketsan with the leadership and support of TNFC engineers and operator personnel, as well as the participation of several domestic companies. The AKYA Phase-2 Project was signed between the SSB and Roketsan in July 2016 to industrialize the AKYA National HWT prototype (controlled test torpedo) and make it ready for serial production by developing its critical subsystems in line with the capabilities of the sector companies. 

The first launch test with the AKYA National HWT prototypes without a warhead and active/passive sonar was successfully carried out on July 11, 2013, in the Sea of Marmara, and a total of 3 test launches were performed until September 2014. The number of countries that can design, develop, and manufacture torpedoes can be counted on the fingers of both hands. Since developing a modern torpedo that can move underwater in three dimensions and has acoustic technology is much more complicated than developing an Air-Launching Cruise Missile (ALCM), the development of the AKYA National HWT with domestic capabilities made a significant contribution to the deterrence of the Turkish Naval Forces and Turkish Armed Forces. In this context, Turkey has become one of the few countries in the world that can develop and manufacture their own indigenous torpedoes and integrate them into their submarines, becoming a member of this ‘elite’ group in the torpedo field. Lastly, the SSB initiated the ORKA National Lightweight Torpedo (LWT) Project, which will be carried out by Roketsan as the Main Contractor and Aselsan as the Main Subcontractor, to meet the 324 mm diameter lightweight torpedo requirements of the Turkish Naval Forces, and the Signing Ceremony was held at the SSB on December 24, 2020.

Equipped with a two-way fiber-optic cable, the AKYA HWT is planned to replace the ageing heavyweight torpedoes (Mk14, Mk23, Mk37 Mod 2, Mk37 Mod 3, SST-4 Mod 0, and Mk24 Mod 2 TigerFish) aboard the Turkish Navy’s submarine fleet. The AKYA HWT is a dual-purpose torpedo that is effective against submarines and surface vessels. It is a battery-powered (Otto Fuel II is not preferred), fiber-optic cable guided heavyweight torpedo, equipped with an active/passive acoustic sonar, magnetic proximity sensor (can be replaced with an acoustic proximity sensor in the future), and wake sensor (wake-homing capability). 

I believe that the AKYA National Heavyweight Torpedo is equipped with a warhead designed to break the keel of the target ship with a "blast" effect by detonating just below the vessel with its adjustable explosion depth feature. Thus, instead of hitting the hull of the target ship, AKYA will explode at a certain depth a few meters below the ship (such as 5m-6m), creating a vast double-layered steam bubble (called the "bubble effect"). The steam bubble will expand rapidly and lift the ship's hull right in the middle, which will weaken the keel. When the steam bubble collapses, the weakened keel cannot bear the ship's weight and breaks into two as the ship falls into the void. AKYA's parabolic nose structure (Conformal Array Sonar is located inside the Parabolic nose cone), wake homing sensor, and warhead configuration reinforce the claims that AKYA was primarily designed for surface targets. I believe that AKYA HWT is fitted with a warhead that weighs between 350-380kg.


The AKYA HWT was initially expected to be tested at the PREVEZE Class Submarines which are being equipped with the MÜREN Indigenous Combat Management System (CMS) under the MÜREN-PREVEZE Project. In our article on page 42 of the 100th issue of Defence Turkey Magazine, we pointed out that the AKYA HWT would be launched from a PREVEZE Class submarine equipped with MÜREN Combat Management System (CMS) in late 2020 or early 2021. However, contrary to our expectations AKYA HWT’s first ever submarine-launched live fire was performed from a GÜR Class submarine TCG Gür.

The MÜREN CMS PREVEZE Class Implementation Project Contract, which is carried out in cooperation with the TNFC Research Center Command (ARMERKOM), Gölcük Shipyard, and TÜBİTAK BİLGEM, was signed in August 2017. Developed by TÜBİTAK BİLGEM for AY Class Submarines, the national production MÜREN Submarine Combat Management System was previously integrated into TCG Doğanay (S-351) and TCG Dolunay (S-352) Submarines under the MÜREN-AY Project, signed in 2016. 

Within the scope of the MÜREN CMS PREVEZE Class Implementation Project, which started in 2017, the ISUS-83/2 Combat Management Systems (CMS) of 4 PREVEZE Class Submarines in the TNFC service will be replaced with MÜREN CMS until 2023. With the project, the PREVEZE Class Submarines will also gain the capability to use DM2A4 SeeHecht and Mk48 Mod 6AT/7AT Heavyweight Torpedoes as well as the AKYA National Heavyweight Torpedo. Under the project, the MÜREN Laboratory was opened within ARMERKOM by the TÜBİTAK Informatics and Information Security Research Center (BİLGEM) in early August 2020. The Laboratory also includes the Land-Based Test Article of the nationally produced MÜREN Integrated Submarine Combat Management System. Within the scope of the MÜREN-PREVEZE Project, all tests before the integration of systems into submarines are carried out in this Laboratory. As the subcontractor of TÜBİTAK BİLGEM, YALTES develops and produces the operator consoles, electronic cabinets, combat data/video networks, and Local Firing Panels for PREVEZE Class Submarines. The existing equipment in the CIC (Combat Information Center) of PREVEZE Class Submarines will be emptied completely, and the ISUS-83/2 CMS will be replaced with the MÜREN CMS. According to the information I received, the MÜREN CMS can manage four different heavyweight torpedo engagements simultaneously.

Two separate modernization projects are currently carried out in parallel for PREVEZE Class Submarines: Mid-Life Upgrade (MLU) and MÜREN CMS. First, the MÜREN CMS PREVEZE Class Implementation Project was initiated. The first submarine equipped with MÜREN CMS is planned to be delivered to the Turkish Naval Forces in June 2021. 

TÜBİTAK BİLGEM had previously developed the Submarine Tactical Simulator (DATAS) for the Submarine Training Center Command in October 2014, which is a kind of reverse engineering work of ISUS-90 CMS and contains quite a lot of detail, including the sonar analysis algorithm. With DATAS, which runs software with more than 4.5 million lines of code, the Combat Information Center (CIC) of the GÜR Class Submarines with ISUS-90/33 Integrated Underwater Command and Control System (IUCCS) was modeled exactly. Surface, maritime, and underwater tactical scenarios can be simulated precisely during training with the DATAS simulator, which creates the technical and tactical conditions of a submarine CIC in a realistic way. With DATAS, tactical and operator training can be given to the submarine commanders, commander candidates, and all personnel of the fire control team 

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