South Korea developing new Super Torpedo
The display included a poster that read:
“Development of key technologies for supercavitating torpedo:
- Supercavitator design technology
- Cavity shapes and hydrodynamic forces prediction technology
- High-speed cavitation tunnel for supercavitation experiment”
An Agency for Defense Development engineer told Navy Recognition that laboratory testing of the weapon had begun in 2015, and live tests are planned for 2020. “The diameter of the current test vehicle is 125 millimeters (for comparison, the famous Russian VA-111 Shkval torpedo is 533mm in diameter),” Navy Recognition said. “The engineer told us that the dimensions of the actual torpedo has not been decided yet. The propulsor was tested with solid fuel and the expected top speed is one hundred meters per second (around two hundred knots, which is similar to the Shkval speed). He added that the supercavitating torpedo is set to have 'a sonar in the head and fins in the back for steering.”
The South Korean project raises two issues. First, supercavitating torpedoes are a controversial technology. Weapons like the Shkval work by using the gases from the rear-mounted rocket to create a bubble around the torpedo, which enables it to avoid friction with the surrounding water. Though the Shkval created quite a stir among Western navies, others  point out that the torpedo is far from a wonder weapon. It has a range of just ten miles, and is noisy and very hard to control. The United States eventually dropped research into supercavitating torpedoes (but not research into supercavitating submarines.
Which raises the next question: Why is South Korea investing resources in such a limited, albeit powerful, weapon? The bulk of North Korea's navy is either its three hundred small missile or torpedo boats, or its seventy old Soviet-made submarines. Both of these can be adequately dealt with existing weapons, or by new ones coming into service, such as multiple rocket launchers to destroy swarms of North Korean small attack boats. While it is natural for any navy to want a super-fast torpedo, this weapon would seem more suitable for nations facing enemies with large surface craft or advanced submarines.