Friday, March 30, 2018

Torpedoes - Then and Now

There is a widespread belief that modern torpedoes are instant and unstoppable death for any modern ship and that carriers and other ships have been rendered nothing more than targets waiting to be sunk.  Of course, we totally debunked that line of thought in a series of previous posts.

Let’s add another nail to that coffin by examining yet another aspect of the unstoppable torpedo myth.  There is a belief that modern torpedoes are somehow more lethal than in the past.  Is that true or just another torpedo-associated myth? 

Here’s a list of some common torpedoes, past and present, and their warhead explosive weights.


Country     Type                  Warhead

WWII Torpedoes

Japanese    Type 93 (Long Lance)  1080 lb
U.S.        Mk14                   643 lb
German      G7e                    616 lb


Modern Torpedoes

Russian     Type 65 Wake Homing   1225 lb
Russian     Type 53                678 lb
U.S.        Mk 48 ADCAP            650 lb
U.K.        Spearfish              660 lb
German      DM2A4 Seehecht         572 lb


It is instantly apparent that that the warhead weights are, on average, no greater today than in WWII and yet the entire world managed to operate vast fleets of ships without being instantly obliterated by torpedoes.  How could that be if torpedoes are instant death?  Well, we’ve already answered that so I won’t repeat it.

One significant change from WWII to now is the guidance mechanism.  WWII torpedoes were generally unguided.  Homing torpedoes were in their infancy towards the end of the war.  Today’s guidance systems offer a greater chance of success. 

Of course, the counterpart to guidance systems are decoy systems such as the U.S. Nixie.

Thus, on balance, it may be that there is no actual increase in success rates!  If it took 4-6 torpedoes to ensure 1-2 hits in WWII, it likely still requires 4-6 torpedoes today to ensure 1-2 hits.

The relevant aspect of this little examination is the realization that modern torpedoes are no more lethal than they were in WWII.  Please note that I am not saying that torpedoes are not a powerful weapon – they certainly are.  However, they are not the instant, one-shot kill that so many people erroneously believe.

The fact that we can now clearly see that modern torpedoes are no more (or less!) lethal than their WWII counterparts should serve to put the torpedo threat in its proper context which is that they are powerful weapons but no more so than many other large weapons.  We can successfully operate fleets of ships in the face of torpedoes just as we did in WWII if we treat the threat with the respect it deserves and apply effective ASW to the threat – which, sadly, we’re not.

34 comments:

  1. This comment has been removed by the author.

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  2. Warhead weight shouldn't be the only factor considered. Fuses are better now and so are the explosives, weight for weight. Capital ships also have less armour. An early WW2 unguided torpedo won't be decoyed so ironically a modern western warship would be defenceless beyond manouevre against the lesser technology.

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    1. Yes, good point about the construction of modern ships. Also, interesting observation about the susceptibility of modern ships to lesser technology. The British sub that sank the Argentine Belgrano used unguided torpedoes. There is a lot to be said for simpler technology!

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    2. Interstingly, the reason he didn't use his Tigerfish homing torpedos was because they weren't considered reliable. They'd failed multiple tests, and weren't fixed properly till post-falklands.

      Wiki has a reasonable summary.

      https://en.wikipedia.org/wiki/Tigerfish_(torpedo)

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    3. "Interstingly, the reason he didn't use his Tigerfish homing torpedos was because they weren't considered reliable."

      Good reminder!

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  3. While I agree that modern torpedoes are not instant unstoppable death, But I think you are missing an important point. Warhead weight for WWII and modern torpedoes might be similar, but modern torpedoes use a different type of explosives than their WWII counterparts. For example, pound for pound the PBNX-103 used in the warhead of a Mk 48 has about 25% more explosive power than the Torpex used on the Mk 14. So, the lethality of most modern torpedoes has improved, along with the guidance.
    Again, this does not make modern torpedoes instant, unstoppable death, but it does mak them more dangerous than their WWII counterparts.

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    1. Yes, good point about explosive composition and if I knew enough about it I'd include a detailed analysis of it but, unfortunately, I don't. Still, the explosive effectiveness is a fractional increase as opposed to, say, doubling the weight of explosive.

      I also have absolutely no feel for what a fractional increase in explosive power means in terms of actual damage. For example, increasing the speed of a bullet by ten or twenty percent does not increase lethality.

      Given that most torpedoes today are designed to explode under the ship, rather than in contact with it, I'm not sure how much difference a bit more explosive efficiency makes. Perhaps a slightly bigger bubble, which we've already demonstrated has no effect, per se, or a slightly higher pressure initial shock wave (how much higher???) which does have a damaging effect but how much pressure translates to how much damage? You can see why I didn't include comparative explosive compositions.

      If you're an explosives damage expert, let me know. I'd love to have an expert do a post on this!

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    2. I'll look into the re factors once I get the time.

      But fractional increases are significant in regards to explosives. I'll let you know once I dig into this further.



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    3. https://en.wikipedia.org/wiki/TNT_equivalent has RE Factors for many common explosives.

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    4. Thank you ats. I have some books covering effects of explosives, particularly in regards to water. Unfortunately, I've become rather busy since I said I would dig into this. I'm hoping to be able to post my findings here before the 30 day cutoff.

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    5. Andrew, comments can be freely made after 30 days, they just need to be moderated before posting. All that means is that I take a glance at them to be sure they aren't spam. I had been getting a lot of attempts to insert spam into older posts. Moderating seems to have completely stopped it. So, comment freely and just recognize that there will be a slight delay before it appears.

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  4. Modern torpedoes are also faster than their WWII counterparts which increases their lethality. The US Mk 14 torpedo had a speed of 46 knots at 4,500 yards and just over 30 knots at 9,000 yards. The Mk 48 is reported to be capable of 55 knots for 35,000 yards. As they say, speed kills.

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    1. Torpedo speed doesn't increase lethality. It may decrease the response time by a little bit but it doesn't make the torpedo any more lethal. If the torpedo is going to be decoyed, it's going to happen regardless of the torpedo's speed. Similarly, if it's going to bypass the decoys it will do so not because of speed.

      Only in the rare case of a ship perched right on the edge of escape distance might speed make a difference.

      Also, the converse of speed is range. The greater the speed, the less the range which, using that logic, decreases lethality.

      Thus, I consider speed to be a neutral characteristic. What speed does is potentially increase the survivability of the submarine that launches the torpedo because the torp will get there (or not) quicker and the sub won't have to hang around as long. Even this is a pretty marginal effect.

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    2. It would seem that speed increases the likelihood of a hit, not the destructiveness.

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  5. Brian Clark does not think that Russia's nuclear armed torpedo is effective right now..
    http://nationalinterest.org/blog/the-buzz/just-how-much-threat-russias-status-6-nuclear-torpedo-24094
    Paul

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  6. The main issue here is that the the users of modern torpedoes - submarines have become drastically more lethal as a combined weapons system. i think even in a conventional scenario without the use on nukes, near peer submarine warfare with China is kinda equaled to the definition of M.A.D

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    1. You're quite right that the overall system (sub + torpedo) lethality has increased because the submarine capabilities have increased so much but that wasn't the point of the post. The post was specifically intended to counter the claim that modern torpedoes are more lethal than their WWII counterparts.

      Of course, while the capabilities of subs have increased, so to has the ASW with many capabilities undreamed of in WWII!

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  7. CNO, could you discuss the effectiveness of light weight ASW torpedoes (Mk-46, Mk-54, etc.) They are the only ASW weapons carried by surface ships today and, as far as I know, they haven’t been used in combat.

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    1. Nobody outside the Navy (and maybe not within!) has any idea about the effectiveness but supposedly they were nothing more than an annoyance for the old double hulled, titanium, Russian subs. Presumably, they'd be a bit more of a threat to smaller, thinner-skinned SSKs.

      Now, as far as effectiveness in shallow water, they are questionable. The Mk54 was the subject of an Urgent Operational Need Statement (UONS) which cited deficiencies in shallow water, anti-SSK use. The subsequent upgrade effort was severely criticized by DOT&E after poor testing performances.

      I don't know what the current status is.

      I would evaluate the light weight torpedoes as marginally effective. Again, this makes the Navy's refusal to obtain a true SSK for testing all the more baffling.

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    2. The RN used a lightweight torpedo against a moored submerged Porpoise class SSK (predecessor to the Oberon). They were going to raise the wreck but decided that it was not worth the effort - such was the damage.

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  8. Thanks!

    In your opinion, what kind of ASW weapon should be carried by small surface escorts (frigates, corvettes)?

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    1. Every weapon! You never know what will come in handy. Actually, there aren't that many anti-sub weapons in the U.S. Navy, sadly.

      The light weight (and only marginally effective) torpedo and ASROC (also a torpedo) are the only ship mounted anti-sub weapons we have.

      We desperately need a Russian RBU type weapon.

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  9. "unguided torpedo won't be decoyed so ironically a modern western warship"

    Witch brings me to the question, do modern torpedoes have a mode in witch they can be essentially fired unguided ?

    Like after launch they only move forward, just like a unguided torpedo.

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    1. Interesting question. I have no idea. I've never heard of it but it would certainly be simple enough to do.

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  10. "Given that most torpedoes today are designed to explode under the ship, rather than in contact with it,"

    And what about shaped charged torpedo warheads that basically act like a anti - tank rocket ?

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    1. Ha ?! The Germans demonstrate a torpedo with modular batteries witch they claim has a range of around 140 km, how that is gonna be guided i don't know.

      https://www.youtube.com/watch?time_continue=111&v=TYvt3tU2yqU

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    2. Off the top of my head, I'm not aware of any torpedo whose primary fuzing is contact. Do you know of one?

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  11. All, the ones i know and you probably are non-guided mostly old designs. However i rudimentary contact fuze would seem logical as a fall back.

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  12. Assuming their quality control is alright, surely a wake-homing torpedo like the Russian one you cited would not be drawn off by a system like Nixie and would have a much higher hit rate than either a WW2 torpedo or a conventional homing torpedo. The USN is developing the Countermeasure Anti-Torpedo to counteract such a weapon, but I don't believe it is in service yet.

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    1. Wake homing torpedoes are not susceptible to Nixie which is an acoustic decoy. This is what has spurred the U.S. to develop the anti-torpedo torpedo system which has been installed on the carriers even though it is not yet fully developed - so, it is in service.

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  13. I was wondering, why don't modern fast jets carry any torpedoes?
    It would seem useful in certain scenarios.

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    1. Well, there was the S-3 Viking for ASW, of course. For ASuW, I guess cruise missiles are considered to be superior.

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  14. Doesn't the new anti torpedo weapons the US is fielding. Kinda changes the game a bit.

    http://www.thedrive.com/the-war-zone/5543/the-navy-is-quietly-arming-its-supercarriers-with-anti-torpedo-torpedoes

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    1. It all depends how well the system works. The first air to air missiles were, theoretically, game changers except for the fact that they didn't work. Now, many years later, they are more effective. History suggests that the system will not work well for quite some time yet!

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