DSEI 2025 – Arquimea unveils S-Wise, its underwater loitering munition system
Active in the air loitering munition domain, Arquimea of Spain is extending its portfolio in loitering munitions and with the acquisition of Perseo Techworks it entered the naval loitering munition field, adding the S-Wise underwater system to its catalogue
A few days before DSEI opened its doors to international visitors, Arquimea announced the acquisition of Perseo Techworks. This anticipated the showcasing of the S-Wise underwater loitering munition, developed by Perseo, on the Arquimea booth. In fact the system is not fully new, as it was seen at FEINDEF 2023 in Madrid, when Perseo showcased it at the Navantia booth, the Madrid-based company being at that time teamed with the major Spanish shipyard and with SAES, the Navantia-controlled company active in sonar and submarine defence, to present the so-called S-UUV, where S stood for small, the team planning developing a medium and a large version. The S-Wise seen in London is very similar to the S-UUV, although it is now a product, as it has been thoroughly tested at sea and is ready for production, and many more details were made available.
Calling it a loitering munition is in fact slightly reductive, as in fact the S-Wise is a multirole platform, that can be used in the suicide mode, carrying a lethal package, defined as loitering munition- intelligence surveillance reconnaissance (LM/ISR) as well as in the mine countermeasure-intelligence surveillance and reconnaissance (MCM/ISR) roles. EDR On-Line understood that the platform computer is loaded with software coping with both options, therefore it is only a matter of replacing the bow section, which can host either the 5 kg primary warhead, which is available in the single or tandem shaped charge versions, or a forward-looking sonar, the Teledyne BlueView M900/2250.
The S-Wise is 2.23 metres long, the maximum diameter is 0.245 metres although the hull is not cylindric; hydrodynamically shaped at the front, at midship the diameter is considerably reduced, two wings being hinged under the hull which deploy forward, wingspan being 0.824 metres. These are moved by a single actuator, designed, and produced in-house, and provide hydrodynamic lift allowing to change attitude, increasing manoeuvrability. The sail goes all along the hull, stopping short of the payload section and of the rudder section. At stern we find the X-shaped rudder complex, each one of the four moving surfaces being activated by an actuator, also produced in-house. The S-Wise nominal mass is 50 kg, to which 30+ kg of payload can be added, payload volume being over 30 litres.
On the S-Wise seen at DSEI propulsion was ensured by two three-blade counter-rotating screws; EDR On-Line understood that the propulsion configuration can be adapted to the mission, the two-crew solution being the best option when stealthness is required, while when priority is speeding a single screw will be adopted. Three electric motors provide 3 kW maximum continuous rating, 6 kW being available in overboost. Power is provided by a series of Li-Ion batteries with a 1.82 kWh of energy, with a 24 V output, the battery management system being developed by Arquimea itself. The maximum surge speed attainable by the S-Wise is over 8 knots; Arquimea provides autonomy figures, which are 85 NM at 2.75 knots surfaced, while submerged two data are available, 80 NM at 3.00 knots and 30 NM at 5.20 knots. The S-Wise can operate in sea state 4-5, while launch and recovery operations can be performed up to sea state 3-4.
The hydrodynamic hull is produced using additive manufacturing and acoustically transparent plastics, which allows installing sonars inside the hull. Sub-sea housings are also in plastic material; when additive manufacturing is used maximum depth is 50 metres, which increases to 300 metres when conventional housings are installed. According to Arquimea, the manufacturing method as well as the material used enable distributed repair, spare-part production, or even complete manufacturing on remote locations or aboard ships. The company also underlines that the production method makes the S-Wise the most cost-effective solution in its class.
The core of the S-Wise is the navigation and control system. The “brain” of the system is based on a Perseo ORA on board computer with edge computing capability, it features a dedicated graphic processing unit capable to handle convolutional neural networks (CNNs), specifically designed for supporting artificial intelligence-based automatic target recognition algorithms, optimised to work with electro-optical and sonar generated images. These provide object detection and tracking, obstacle avoidance and follow-me functions, objects of interest being dynamically positioned on the map. Data can be shared with other units using advanced persistence algorithms.
The S-Wise is fitted with a comprehensive navigation suite which includes an inertial measurement unit and geomagnetic device, a static and dynamic pressure sensor, GNSS, and optionally a doppler velocity log.
Back to payloads, in the MCM/ISR configuration an Arc Scout MK II side scan sonar and a Ranger synthetic aperture sonar can be installed, their antennas being located midship on the hull sides. When used in the LM/ISR configuration, these antennas can be removed, fixed wings being added which carry secondary high explosive charges bringing the total mass of explosive up to maximum payload; these will also generate battery detonation, increasing the energy by 120-270 MJ.
The S-Wise package includes a mission planning and an advanced training system; this allows not only crew training but also operational experimentation, the use of synthetic images also to operate in a realistic environment. The Arquimea underwater loitering munition maintains the man in the loop, the operator monitoring and interfacing with the munition via a ground control station that communicates via WiFi, LTE/5G or Long Range links with the platform when surfaced, a USBL (Ultra-Short BaseLine) underwater link being available as option to communicate with the S-Wise when this is submerged.
Photos courtesy Arquimea and P. Valpolini
