USN wants anti-torpedo torpedoes

In its most recent budget proposal, the U.S. Navy says that it is interested in giving its submarines the ability to launch small torpedoes.

Virtually all of the services existing submarines use variants of this software-driven combat control architecture to launch weapons and other payloads, via combinations of torpedo tubes, vertical launch systems, or countermeasures launchers, depending on the particular design.

The budget line also specifically mentions an Anti-Torpedo Compact Rapid Attack Weapons program as a possible new payload to integrate into the AN/BYG-1s control systems.

When asked, the Navy would not officially confirm that there are fixed plans to add either an Anti-Torpedo or a Compact Rapid Attack Weapons capability to its submarines.

We are investigating options to transition efforts that were executed under the ATTDS Program and other RDT&E efforts in support of the Compact Rapid Attack Weapons.

The mini-torpedo has a Stored Chemical Energy Power Systems (SCEPS) power system for its propulsor in the rear. SCEPS works by bathing a solid block of lithium in sulfur hexafluoride gas, creating an extremely energetic chemical reaction that, in turn, produces steam to drive a turbine engine.

At six and three-quarters inches in diameter and approximately 85 inches long, the CVLWT is significantly smaller than the latest variants of the Navy’s Mk 48 heavyweight torpedo, which is the standard weapon of this type for its submarines now.

The Navy has already developed multiple variants of the CVLWT, the best known of which is the Countermeasure Anti-Torpedo (CAT), also called the Anti-Torpedo Torpedo (ATT). This is a defensive “hard-kill” interceptor that is supposed to destroy incoming torpedoes by either slamming into them or destroying them with its explosive warhead.

The interceptor also features a sonar seeker capable of operating in active and passive modes, together with a guidance package that also includes an Inertial Measuring Unit (IMU). The IMU provides data that allows the torpedo to make more precise movements, making it more maneuverable and improving its accuracy.

The Compact Rapid Attack Weapon (CRAW) has much of the same hardware, the bulk of which consists of Commercial Off-The-Shelf components to help keep production costs and maintenance requirements low, according to public Navy briefings and other documentation, but is optimized as an offensive weapon against other submarines. Both variants could offer important capabilities for various American submarines.

At present, American submarines use a combination of electronic warfare jammers and acoustic decoys to defeat incoming torpedoes. This works well against threats that use active and passive sonar to home in on their targets.

More advanced torpedoes, however, which feature sensors to detect differences in water density to zero in on the wake a ship or submarine churns up as it moves, are immune to acoustic decoys and are jamming resistant.