Now, here’s a thing

Uncrewed vehicles are now mainstream weapon systems universally regarded as essential both to deploy and to counter in fields of conflict. So far, most effort has been directed at bringing down UAVs, but now maritime drones are getting more attention, writes Peter Donaldson.

Much of that attention and the most rapid progress is happening in Russia because its Black Sea fleet has famously taken significant damage from ‘kamikaze’ USVs, many of UK origin. Russia has put a number of countermeasures into service, including helicopters armed initially with guns, rockets, guided missiles and, more recently, FPV drones capable of destroying small, fast, agile surface targets.

With a different set of uncrewed threats in its sights, Russian underwater weapons house Gidropribor has been presenting a new small torpedo (‘UMT’) at military trade shows for a few years now – a weapon explicitly intended to engage UUVs and USVs in addition to submarines and certain classes of surface ships. The UMT features an acoustic homing head and fibre-optic guidance enabling target updates from the launch platform and networked sensors. Its digital homing system has been optimised for quiet targets with low acoustic reflectivity.

Neither the torpedo’s publicised top speed of 27 knots nor its stated range of 5–7 km is high compared with the corresponding values of other torpedoes, but its performance is likely more than adequate to deal with large slow UUVs and USVs. Those figures are marginal for non-nuclear submarines, which achieve around 20 knots submerged, and clearly inadequate for nuclear submarines capable of 35 knots – unless launch conditions are close to perfect and the target sub is moving slowly because the target is most unlikely to out-accelerate the torpedo.

The low weight and compact dimensions of the UMT mean that it is suited to a wide variety of launch platforms on the surface, under water and in the air, including UAVs, UUVs, USVs and even missiles. Measuring 220 mm in diameter and weighing 100–140 kg, depending on configuration, it carries a 35 kg warhead. This makes it smaller than established lightweight torpedoes launched from maritime patrol aircraft and helicopters. Such weapons typically have diameters of 324 mm and weigh around 275 kg, while typical heavyweight torpedoes, for comparison, are 533 mm in diameter and weigh more than 1650 kg.

The new Russian torpedo’s target set overlaps that of a similar US weapon developed by Northrop Grumman, namely the Very Lightweight Torpedo (VLWT). Although intended to counter swarming threats, likely including USVs and UUVs, the most challenging target that the VLWT is designed to engage is an incoming enemy torpedo – a requirement that sent the engineering in very different directions, with a focus on high speed that probably sacrifices range and endurance.

While the VLWT is significantly smaller in diameter than the UMT at 171 mm, the two torpedoes are similar in terms of length and weight, with the VLWT coming in at about 2.16 m and around 100 kg, making them both suited to a similar set of launch platforms.

The VLWT’s speed has not been revealed, but it is likely to be fast because heavyweight torpedoes can achieve 70 knots or more and it will need a substantial margin to intercept them. Its operational profile includes a target acquisition phase conducted at low speed, followed by a high-speed engagement phase, for which its propulsion system is sized to produce 100 hp for 10 min.

Designers of USVs and UUVs will have to come up with cost-effective countermeasures against such weapons.