Sweden’s Defence Materiel Administration (Försvarets materielverk – FMV) has outlined its future torpedo capability roadmap, including a leaning towards the development of a next-generation electrically-powered heavyweight weapon – known as Torpedo 63 – derived from the new Torpedo 47 lightweight.
Speaking at Navy Leaders’ Navy Tech 2025 conference in Helsinki on 12 February, FMV’s product manager torpedo systems Anders Svensson said that the investment case for Torpedo 63 was being weighed against further development of the current thermal-powered Torpedo 62 weapon.
Sweden – through the partnership of FMV, Saab, the Swedish Defence Research Agency and the Swedish Armed Forces – maintains an indigenous capability for the design, development, production and support of underwater weapons. This reflects both the desire to maintain sovereign technical and industrial resource, and the need to develop weapons optimised for the complex operating environment of the Baltic and the Swedish archipelago.
The Royal Swedish Navy is currently in the process of replacing the ageing Torpedo 45 lightweight with the new Torpedo 47. The latter is a new 400 mm diameter weapon using a rechargeable Lithium Iron Phosphate battery for both exercise and warshot use, and the adoption of a pumpjet propulsor in place of the contra-rotating propellers used in Torpedo 45. Other features of the new weapon include the MS4 active/passive digital homing head for detection, classification and tracking of targets; two-way data communications with the launch platform via a wire link; a high accuracy navigation system; and a wide stepless speed range.
Saab began deliveries of Torpedo 47 in late 2022, with the system becoming operational the following year. The weapon is being fielded in both submarines and Visby class corvettes (being launched from a new M/20 tube launcher in the latter). Further procurements of torpedoes and tubes are planned for the new Luleå-class surface combatants, and work is also underway to explore the integration of Torpedo 47 in ‘non-traditional’ (likely uncrewed) platforms.
According to Svensson, FMV is already considering a number of improvements to Torpedo 47. “We want to import additional passive functionality from the heavyweight torpedo to have commonality between the two,” he said. “Also, we want to move to a higher energy propulsion system….Lithium Iron Phosphate was chosen as a low-risk and very safe chemistry, but we are now looking into Lithium Nickel Manganese Cobalt Oxide [NMC] energy systems.”
Other potential Torpedo 47 upgrades include a wideband (multi-frequency) acoustic homing head, improved wake-homing performance; replacement of the copper wire guidance with a fibre-optic link; and anti-torpedo/anti-autonomous underwater vehicle functionality.
New heavyweight torpedo
Turning to submarine-launched heavyweight weapons, Svensson said that the current Torpedo 62 – which uses a bi-propellant propulsion system (a combination of 85% HTP and 15% kerosene) to power a seven-cylinder axial piston engine – has now passed its 20-year design life. “We are now under a lifetime extension, and are considering what to do for the next 20 years,” he told the Navy Tech 2025 audience. “We are then comparing whether we invest a lot in the Torpedo 62, or if we re-use a lot of the Torpedo 47 development in a new electric Torpedo 63 heavyweight.”
Significant study work and prototyping has already been completed to inform comparisons of both performance and lifecycle costs. FMV’s original planning assumption had been to keep Torpedo 62 in service until 2042; Saab was awarded a four-year contract back in July 2020 for feasibility studies and prototyping intended to identify candidate modifications and enhancements, complete a baseline review, and start preparations for future stages of the life-extension programme.
“We can do that, and keep the weapon safe, but that is without changing any electronics units,” said Svensson. “So that will probably lead to temporisation and so on [unless] we do a Phase 2 LTF [lifetime extension] that comes in 2027, 2028 and 2029.
“But that would almost cost as much as to build a new torpedo because the logic, the software, the [homing] head and the warhead is a big part of the torpedo, not just the energy system. So it would be much more cost effective to make a Torpedo 63 now. So that is, I think, the way that Sweden will go.”
Svensson’s presentation suggested that project definition and technical de-risking activity could pave the way for Torpedo 63 development to commence at the start of 2027, transitioning to production from 2031. First warshots could be operational in 2032.
“We have already done a prototype phase for the [Torpedo] 63 where we looked into energy systems, [homing] heads and everything like that,” he said, adding that NMC technology promised significant performance gains compared to earlier battery chemistries. “We now believe that we could now get the same performance as we do in the old [thermal] engine torpedo. That is to say, well above 50 km and speeds of up to 50 knots at continuous maximum speed.” The Torpedo 63 acoustic head would derive directly from Torpedo 47, albeit with the possible enhancements to passive homing capability and lower frequency coverage. Other key Torpedo 47 technologies adapted for Torpedo 63 would include the main computer, software, and warhead. Use of a fibre-optic link would increase data rate, and potentially enable a further range increase.
