IDEF 2023 – STM goes . . . underwater!

Paolo Valpolini

STM, the Turkish engineering company involved in naval and UAV production, announced at IDEF 2023 some progresses in the underwater domain, more specifically on the STM500 shallow water submarine

Soon Turkey will enter the club of those nations capable to design and produce a submarine; at IDEF 2023 Özgür Güleryüz, the STM General Manager, announced that the first elements of the STM500, the shallow water submarine designed by his company, have started being assembled. EDR On-Line understood that a ceremony to mark the event will be organised after the end of the IDEF exhibition.

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The STM500 is a 42 metres long submarine with a 4.2 metres diameter, a maximum height of 8,5 metres, with a 485 tonnes displacement surfaced and 540 tonnes submersed. Two diesel generators ensure the charge of the Lithium-Ion battery pack that powers the 1.5 MW permanently excited propulsion motor driving the screw. Maximum speed is in excess of 18 knots, while cruising speed is 5 knots. The STM500 has an endurance of 3,500 Nautical Miles when running on diesel, while on batteries the range is 75 NM. As option STM offers an Air Independent Propulsion system, which brings the endurance to 4,000 NM.

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Maximum diving depth is of over 250 metres, while endurance is 30 days. “A submarine that can carry out missions of bigger boats with a cost slightly higher than a midget,” this is how STM sources defined the STM500. In fact the company considers it can carry out submarine warfare, ISR missions, special operations (an Underwater Swimmers Delivery vehicle was installed behind the conning tower on the model exhibited in Istanbul), mine warfare, although shallow waters should be by design the STM submarine optimal operational playground.

The STM500 has accommodation for 18 crew members plus the captain, and can also host six Special Forces operators. It has four 533 mm torpedo tubes, two of them for guided weapons, four spare torpedoes being hosted aboard.

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A number of sensors are installed, starting from optronic search and attack periscopes, ESM and navigation radar being also installed. A whole series of sonars is installed; continuous active sonar, passive ranging sonar, multi-aperture side-scan sonar, and intercept detection and ranging sonar, an own noise analysis sensor. For self-protection the STM500 is fitted with torpedo counter measures.

STM will start assembling the building blocks in late 2024; asked about a potential customer, building a submarine albeit of reduced dimension is definitely a considerable investment, STM did not comment.

In 2024 STM will also float its first Underwater Autonomous System (UAS), which development was also announced at IDEF 2023. According to what was said by the company General Manager, this should be a platform capable to accept a modular payload in order to be adapted to different types of missions. No information on dimensions and performances were provided.

Photos by P. Valpolini