Friday, November 17, 2017

Korean Supercavitating Torpedo

As reported by Navy Recognition website, South Korea displayed a supercavitating torpedo it’s developing at the MADEX 2017 International Maritime Defense Industry Exhibition held in October 2017 (1).  Development began in 2013 and at sea tests will take place around 2020.

The “vehicle” as it’s referred to in the article, is 125 mm (~5 “) diameter, is solid fueled, and has a top speed of 100 m/sec (around 200 kts).

If one believes Russian reports (always a risky business!), their supercavitating Shkval torpedo is 533 mm diameter, 200 kts, and 20 km (~12 miles) range.

Iran supposedly is developing a reverse engineered version of the Russian Shkval and a German firm developed a supercavitating torpedo although it never transitioned to a service weapon.

The takeaway from this is that the US Navy is falling significantly behind in torpedo development.  The Navy’s standard heavyweight Mk48/ADCAP torpedo was designed in the 1960’s and became operational in 1972.  There has been little development since then although some effort has been directed towards enhancing shallow water performance.  Beyond that, though, torpedo development has been stagnant.

On a related note, the major challenge with a supercavitating torpedo is guidance.  The formation of the air "bubble" that the torpedo travels in is deafeningly loud as far as sonar guidance is concerned.  Supercavitating torpedoes are blind.  Supposedly, a Russian version was intended to sprint to the target location and then slow down to "normal" torpedo speeds in order to acquire the target.

Torpedo development is one of several areas that the Navy has, bafflingly, neglected.  Offensive mine warfare has all but halted, mine countermeasures have atrophied to near non-existence, naval gun support is non-existent, anti-ship missile development has only recently made any advancements after many years of neglect and, even now, significantly lags Russian, Chinese, and Indian weapons.

The Navy’s myopic focus on new Burke, carrier, and LCS funding and construction has led to neglect of vital but less “sexy” weapons, equipment, and systems.  We are now being surpassed by friend and foe alike in many of these areas.


(1)Navy Recognition website, “MADEX 2017: South Korea Developing a Supercavitating Torpedo”, 10-Nov-2017,


  1. How about wire guidance, if they get that to work the supercavitating torpedo does not need its own seeker.

    On another note, the early versions of the Shkval and for sure the ones that have been sold outside Russia are non guided. In fact some Russian sources refer to them as underwater rockets witch is a more precise description.
    What is not so dangerous to one vessel is deadly dangerous to another, sure its hard to hit a modern submarine that has been alerted to you presence with a unguided Shkval, but if you use them against large surface combatants in a surprise attack reaction time is nonexistent.

    1. "wire guidance"

      That might work if the wire is survivable in the wake of the torpedo. I would guess it's pretty violent. I have no idea whether a cable could withstand the forces. I also have no idea whether a cable could run out from its spool that fast.

      Also, wire guidance requires that the sub have a fix on the target which implies a fairly close range.

      "reaction time is nonexistent."

      Not necessarily - depends on the launch range. If the launch is from 300 yds, then, yes the reaction is non-existent but that would be true for a conventional torpedo, too, for all practical purposes. However, let's say a more realistic launch range of 10 nm. At 200 kts, that's 3.3 nm per minute which would be a travel time of 3 minutes. Assuming the target ship was on wartime alert, three minutes to turn the ship out of the path of an unguided torpedo is plenty of time. The torpedo, being incredibly noisy, will be detected immediately upon firing so the reaction time would be the full three minutes. This is why some form of guidance is needed.

    2. Well, the British torpedoes like the Tigerish and Spearfish have wire guidance modes, and not only them.

      So i guess for a faster torpedo it would require a stronger wire probably made of some strong and elastic materials.

  2. Is it good idea to keep a fleet in a tight formation nowadays? Recently, our Navy had three carriers steaming abrest. This makes a huge target area so even unguided weapons should hit something. What's the point of decoying a missile or torpedo to miss by 100 meters if it will hit a nearby ship? How do you employ CWIS and SeaRAM safely with other ships close by?

    1. No, three carriers don't sail next to each other. That was just a photo op. Carriers operate many miles apart.

      Think about it. Just the room needed to launch and land aircraft requires miles. Trying to operate three carriers close together would cause mid-air crashes!

      Rest assured, carriers operate far apart and their escorts operate miles further out from the carriers. All the photos you see of ships near each other are just photo ops.

  3. The takeaway from this is that the US Navy is falling significantly behind in torpedo development.

    This may very well be true, but it's not supported by the discussion of fielding supercavitating torpedoes. There have been efforts in that area on the US side for years but many of the challenges that have already been discussed have led the USN to continue with improvements to the MK 48. From what I understand, some of the concepts involved slowing down to re-detect the target, re-orient direction, and then speed up again.

    The Navy’s standard heavyweight Mk48/ADCAP torpedo was designed in the 1960’s and became operational in 1972. There has been little development since then

    To be fair, there is almost no resemblance to a MK 48 from 1972 and a MK 48 today. Some mechanical engine elements and fuel system are the same, but even the engine experienced a significant overhaul between the MK 48 MOD 5 and MK 48 MOD 6, and the electronic sections were changed out between the MK 48 MOD 6 and MK 48 MOD 7. Additional modifications are planned that would further change the electronic sections.

    Now, where it would be fair to say that development has lagged is in the energetics. The warhead is largely the same since 1972 and while it’s a fairly effective explosive compound, there is room for improving the fuzing and doing basic research on new explosive fills that would provide greater net explosive weight. The propulsion system also uses Otto II fuel. The Navy has a long track record with Otto fuel and has a vast body of knowledge of the system, but there is little basic research on improved fuels to improve range without sacrificing speed and vice versa. The other alternative is to go a different route with propulsion (electric, store chemical energy, etc) and my understanding is that there are some efforts in going that route.

    USN also typically doesn't do multiple concurrence developments, which is shame because I think that the internal competition would do the warfare area a great service. All it takes is some funding...

    1. The Mk48 has not improved its combat effectiveness. As you say, the warhead is the same. The guidance is essentially the same. The fuzing is the same. The speed has not increased. The stealthiness has not improved. The torpedo is still not suitable for shallow water. While some electronic components may have been swapped out over the decades, the combat performance of the Mk48 is virtually unchanged. I'd say that qualifies as a lack of development.

    2. : doing basic research on new explosive

      The problem is, the Navy significantly reduced funding for basic research on new explosives, because the high ranking decision-makers have got too excited about the directed energy weapons. And so they believe that lasers and railguns will replace existing powder guns and even some missiles in 20-30 years:

    3. The Mk48 has not improved its combat effectiveness. ...The stealthiness has not improved. ... the combat performance of the Mk48 is virtually unchanged.

      That's not entirely true...the propulsion modification from the MOD 5 to the MOD 6 was largely intended to decrease noise, increasing stealthiness (counter-counter detection). And significant improvements were made to the electronics, allowing for more complex on-board processing, which is paramount for a software-driven weapon in a complex environment.

    4. Wow, you are really reaching in an attempt to be able to say that the Mk48 has improved! Would it make you feel better if, instead of saying the Mk48 has not improved, I say that the Mk48 has improved very slightly over the decades?

      Setting aside an irrelevant debate over the degree of very slight improvement, the point in the post was that torpedo development has lagged many other areas. The Navy has devoted the same degree of attention to torpedoes as it has to, say, unmanned vehicles or rail guns or lasers or radar or ... well, you get the idea. The Navy has allowed certain areas like torpedoes, MCM, naval gunfire, etc. to languish. Other countries are well ahead of the US in torpedo development. Russia, in particular, has far more effective torpedoes.

    5. Other countries are well ahead of the US in torpedo development. Russia, in particular, has far more effective torpedoes.

      What is the basis for the assertion/conclusion, particularly about Russia?

    6. The basis is the capabilities of Russian torpedoes. I'm not going to spend too much time describing this because it's something you can easily research yourself on the Internet but here are a few examples.


      -Most (all?) torp versions have wake homing capability which is something we still do not have and which makes the torpedoes immune to countermeasures

      -The Type 65 has a warhead of around 1000 lbs versus the Mk48's 650 lbs

      -The Type 65 has a max range of around 100 km versus the Mk48's range of around 50 km

      -The Type 53 UGST has a range of 60 km and a speed of 65 kts which is far better than the Mk48

      -The Futlyar is an infrared homing (heat seeking) torpedo with 60 kt speed and 60 km range

      I can go on but this is more than enough to demonstrate that Russia is far more advanced in torpedo development than the US.

    7. Actually, the Type 65 has been pulled out of service courtesy of the Kursk Disaster. All modern Russian Subs only have 533mm tubes with existing 650mms refitted to fire the former caliber.
      Also the Mk48 official range and speed are classified so honestly the 50km range and 55kt speed is an estimate rather than a fact.
      Other than that, I agree that the current Mk48 does not have wake-homing or an infrared homing system.
      Supercavitating itself alone is a rather dubious capability, seeing as it comes with cons like limited maneuverability and guidance systems due to it's very nature. If a nation can come up with a terminal supercavitation for a standard torpedo I will be impressed.

  4. I wonder if it would be possible for a supercavitating torpedo to use a small teardrop shaped probe, extended ahead of the nozzle for sensing/target tracking.

    1. I doubt it. Flow noise would obscure any signal. Flow noise over the sensor is why ships and subs slow down to conduct searches.

    2. Ahhh, ok that makes sense. I was thinking the cavitation was the primary culprit.

  5. Domo, I've deleted your comment because it's totally incorrect. Russia, Germany, and SKorea have all developed working prototypes so, yes, it can be done.

    You also have completely misunderstood the operating principle. Supercavitating torpedoes don't use propellers. They apparently use rocket engines. The air cavity is formed by superheated steam released from the nose of the torpedo which vaporizes a thin band of water, creating the "air" in which the torpedo "flies".

    There are videos on line showing test launches.

    Please do some research and then feel free to repost.

  6. "To be fair, there is almost no resemblance to a MK 48 from 1972 and a MK 48 today"
    Hmm, could be right.
    I mean look a a Standard missile from the 70ties and now, only same thing is the name.
    Same thing goes for a lot of US missile systems and other weapon systems.

  7. Given its size and the test video, I can't imagine this torpedo has a range better than a few hundred meters.

    From the pictures, the torpedo appears to be about 18 diameters in length, about 2.25 meters or 7.4 feet. In comparison, the Shkval is 8.2 meters long and weighs 2,700 kilograms according to Wikipedia.

    1. The linked article indicated that this is a test vehicle being used to develop the technology and that the dimensions of the final torpedo have not been decided.

  8. I think the threat is a little exaggerated since there are obvious limitations with current SCTs: limited range, noise, guidance....BUT if somebody could come up with a underwater throttle-able rocket engine (if feasible) NOW you have a problem since you could fire slow, maybe even have a cruise setting for range or scout fast and then slow down again to regain contact, that would be a bad day for any ship or sub....also, maybe have a two stage system, one for range and rocket piggy back just for terminal distance to impact ship might be easier way to go.

    Definitively USN needs to start looking at better decoys and torpedoes itself....

  9. How about hard kill ASTD (anti-ship torpedo defence) as the main role for such a system?

    Geometry is easier to solve since ownship is the target of the enemy inbound, not an enemy submarine. Supercavitation means rapid engagement attempts, reduces errors, and allows multiple defence engagement opportunities per inbound. Rather than sending out an LWT to hit an inbound HWT in an equal speed engagement.

    The fact there is still no good hard kill defence against torpedoes means the submarine Vs ship engagement scenario remains lopsided. Especially since the ship is usually flinging LWTs with a fraction of the range of the submarine's HWTs.

    Particularly given the difficulties detecting small subs in littoral waters, such a defence system is well overdue. In addition to soft kill systems.

    1. That's an intriguing idea. You'd need some sort of self-destruct mechanism so misses wouldn't continue out and hit a friendly escort vessel but that should be doable. Might not even need to have an explosive warhead - the kinetic energy from a direct impact might be enough?

      Good thought!

    2. One limitation to that idea might be the effective depth a SCT. The size of the bubble surrounding the torpedo is affected by the surrounding pressure which increases with depth. I would expect the gas generator for such a torpedo has a pressure compensation system where more gas is expended as depth increases, which would only reduce its range.

  10. A fast and small (125mm) torpedo; I like it. Forget sophisticated guidance systems, make them inexpensive, and buy lots of them. Launch them in groups along with lots of six or eight inch naval gunfire. Try to out maneuver that.


    1. Assuming you're talking about using in the anti-ship role, the problem with a small torpedo is that the warhead will be too small to have any effect. Even a bunch of hits would do very little damage. For comparison, the the Navy's lightweight Mk50/54 torpedo, which is not considered to be an effective anti-ship torpedo, is 324 mm which is 2.5 times bigger!

      Even the Hellfire missile, at 178 mm diameter is bigger than this demo torp and it only has a 18-20 lb warhead.

    2. Just a thought, but the kinetic energy of a small SCT might make up for a lack of explosive power found in a larger torpedo.

    3. Yes, to a degree. I just don't know what degree!

      k.e. = 0.5 * m * v2

      m = 100 kg; a Mk54 torp is 276 kg and this is less than half size so call it 100 kg

      v = 100 m/s; from the article


      k.e. = 0.5 * 100 kg * (100 m/s)*(100 m/s)
      k.e. = 500,000 (kg*m2)/s2 =500,000 J

      By comparison, a kg of TNT releases 4,184,000 J. Thus, the k.e. of the supercavitating torpedo is just 11% of a kg of TNT. A lightweight Mk54 torpedo has a warhead weight of 44 kg (we'll assume it's TNT even though it isn't). That means the supercavitating torp would have kinetic energy equal to 0.3% of the explosive energy of a Mk54 lightweight torpedo - not enough to even be noticed, by comparison.

      Double check my math but I think I'm good on this.


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