Thursday, November 30, 2017

Supercavitating Torpdeo Kinetic Energy

Recently, there have been a few comments asking about the kinetic energy of a supercavitating torpedo with the suggestion being that the kinetic energy, alone, makes the torpedo a one-hit killing weapon against any size ship – essentially vaporizing the target.  Well, kinetic energy is  easily estimated. Here's the calculation for the Russian Shkval supercavitating torpedo.

k.e. = 0.5 * m * v2

m = mass = 2700 kg; Russian Shkval torp

v = velocity = 100 m/s; 200 kts

so,

k.e. = 0.5 * 2700 kg * (100 m/s)*(100 m/s)
k.e. = 13,500,000 (kg*m2)/s2 = 13,500,000 J

By comparison, a kg of TNT releases 4,184,000 J. Thus, the k.e. of the supercavitating torpedo is equivalent to around 3 kg of TNT. To put that into context, a U.S. Navy 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 7% of the explosive energy of a Mk54 lightweight torpedo - not enough to even be noticed, by comparison and certainly not a one-shot kill/vaporize due to kinetic energy alone.

48 comments:

  1. The fuel for this thing is going to take up a minimum 40% of the total mass. By the time it reaches a target its KE is going to be even less than you predict.

    In fact, I would almost bet money that this is the reason this weapon has not proliferated in the four decades its been around. Minus a nuclear payload, it simply does not have the KE/PE to do any real damage.

    The science and engineering are cool, but the effect on target is probably not.

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    1. You're absolutely correct about the KE being less than I calculated by the time the torpedo reaches its target due to the decrease in fuel (meaning mass). Of course, the fuel/mass is a linear effect on KE whereas the velocity is the square but decreased mass does still impact KE. Very good observation.

      The main benefit of supercavitation is the reduced reaction time for the defender. Whether the shorter range and inability to self-guide is worth it is debatable.

      Delete
  2. "not a one-shot kill/vaporize due to kinetic energy alone"

    I think we get too focused on every weapon being a "one shot kill". Just penetrating the hull below the water-line can create a damage control situation; a distraction during an already stressful combat situation. This is assuming said weapon is low cost enough, so I can carry and deploy them in large numbers. That's why I found the South Korean small super-cavitating torpedo interesting, if it could be produced at low cost. Use them in the manner an infantry unit uses the M-249 SAW: lay down cover fire to discourage enemy movement.

    I think the Navy focuses too much on creating the next super high tech wonder weapon, rather than equipping and training the ships and sailors to fight.

    MM-13B

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    1. "I think the Navy focuses too much on creating the next super high tech wonder weapon, rather than equipping and training the ships and sailors to fight."

      Spot on!

      Delete
    2. Just throwing it out there, buying a few of these might give us the opportunity to test with them and actually see what they can do, and how we might counter them.

      To tag on to MM-13B, I think that we so often look for the Uber High Tech solution... it might be that old fashioned torpedo bulges made with modern computer modeling to maximize energy disruption could provide a cheap(ish) fix. Or maybe we discover that the things aren't very good in combat situations.

      But all of this might require live fire testing on a remotely controlled ship that has systems in line with what we have.

      Delete
  3. Of note is the fact that the Russians classify the ВА-111 «Шквал» as a underwater rocket.

    And it has a warhead of 210 kilogram, i think the benefits of that high speed are when the weapon pierces the ship and penetrates deep inside the hull( of course that would require a time delayed primer/ fuse )and after that having the warhead explode, not on contact with the external hull.

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    1. You noted that the KE(max) is 7% of the explosive power of the Navy's LIGHTWEIGHT(!) torpedo? It's not at all clear to me that the KE, alone, is sufficient to penetrate a hull!

      Delete
    2. Well, modern warships don't have armor above or beneath the waterline right?
      So whats to keep a supercavitating torpedo with a pointy nose traveling at such high speeds to punch a hole and then explode.
      You don't think that a vehicle with this profile at 200knots won't be able to penetrate the outer hull at least?

      Delete
    3. As I said, I don't know. It might or it might not. That's not a lot of energy. It's equivalent to a very small explosion. Maybe, maybe not. Neither of us has any idea whether it would be sufficient to punch a hole. Even if it did, it wouldn't penetrate very far at all. All it's KE would be used up in the initial punch.

      Neither of us know! Maybe you can do some research and see if you can find the energy required to penetrate a given thickness of steel?

      Delete
    4. basically
      -shape and speed of the projectile
      -thickness/shape of the Armour/steel

      however we do not know the thickness of the steal used on modern warships hulls.

      All we know that the Shkval, witch you have given as an example weights 2.7 tons and impacts at around 200knots and depending on what you read has a warhead around 200/300 kg.
      However its not mentioned what kind the warhead is, because if it is shaped charged it would be very unpleasant for the receiving ship.

      Delete
    5. It is not a shaped charge warhead. The entire front nose of the torpedo is devoted to generating the "air" bubble that the torpedo rides in.

      I also don't know that the torpedo is even a contact fused torpedo! I've seen nothing on the fusing.

      Delete
    6. And supercavitating torpedoes have blunt noses, which are a necessary part of generating the gas bubble.

      Delete
    7. y'all know there are explosively formed penetrators that do not require a special shape of the front of the projectile

      http://slideplayer.com/slide/3442060/12/images/11/RM+in+Explosively+Formed+Penetrators.jpg

      Delete
    8. Do you have any indication, whatsoever, that the supercavitating torpedo has any kind of special penetrating warhead?

      Similarly, do you have any indication, whatsoever, that the torpedo is even a contact-fused torpedo as opposed to proximity, under-the-hull fused?

      It's time to put up some data or stop making suggestions and claims that are unsupported.

      Delete
    9. The above was to comment that a special shape/form of any vehicle ( high speed torpedo/rocket) is not needed to have a shaped charged warhead

      As for the Shkval its a 210kg, High-explosive squash warhead.
      The export version has a warhead of 350kg.

      http://www.arms-expo.ru/news/vooruzhenie_i_voennaya_tekhnika/rossiyskiy_shkval_odna_iz_luchshikh_podvodnykh_raket_v_mire/

      Delete
    10. I don't read Russian and I don't have a translation that produces anything intelligible. Do you have a link to anything in English?

      Delete
    11. "y'all know there are explosively formed penetrators that do not require a special shape of the front of the projectile"

      I DO know that! However, I suspect that there's a limit to how much equipment you can put in front of the warhead and still expect it to work properly. Presumably, there's a reason why warheads that are expected to have some special function other than just exploding, are placed at the front of the vehicle. This is just supposition on my part as I'm well out of my field on this!

      Delete
    12. The Google translate App is pretty good from English to Russian.
      They're working on the successor right now,

      https://scout.com/military/warrior/Article/Special-ReportNew-High-Tech-Russian-Torpedo--101458903

      https://www.militaryperiscope.com/mdb-smpl/weapons/minetorp/torpedo/w0004768.shtml

      Delete
  4. And some sources cite the export version having a 350kg warhead. Anyways here is a good link

    http://militaryrussia.ru/blog/topic-473.html

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  5. You should have been comparing it not to the TNT equivalent but to a one-ton vehicle moving at 100 miles per hour, as railgun marketeers do ;-)

    ReplyDelete
  6. To determine the effect of impact of a supercavitating torpedo on a ship's hull, let's assume this is analogous to an artillery or naval projectile hitting a plate of armor.
    Doing that allows one (with some assumptions) to use the classical methods to determine the depth of penetration.

    Given the speed and diameter of the Shkval and assuming a weight of 1,000 lbs (I figured that was closer to the Shkval's actual empty weight), I used the De Marre Nickel-Steel formula at Navweaps (link below) and calculated (again with assumptions) that such a torpedo would penetrate less an an inch of steel plate. That's probably not be enough to penetrate the hull of a destroyer or cruiser, but might be enough to initiate local cracking.

    http://www.navweaps.com/index_nathan/Hstfrmla.php

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    1. Looking at the De Marre formula and its relationship to speed, one thought comes to mind: Speed Kills!

      Delete
    2. Great idea to go to those formulas. I'd love to see your work and assumptions.

      I note that the formula is "limited" to shells. For instance, it mentions non-deforming pointed projectiles as one type of shell and all shells have noses designed to aid in the penetration of armor. Thus, a torpedo such as this not only doesn't have a shell-type nose, the nose is decidedly non-penetrating as it houses the steam generator. A reasonable conclusion, then, would be that the calculated penetration would be even less. What do you think?

      Did you assume a zero degree obliquity?

      Speed - yep, you gotta like factors that are squared!

      Really good idea to look at this. It never occurred to me. Full credit to you!

      Delete
    3. Thanks for the kudos! I assumed a zero obliquity angle and 1.2 for the "C" factor. Make sure to use Imperial units. I agree that actual penetration would be less for the reasons given. But, it's good enough for a rough order of magnitude analysis.

      But, if it were able to penetrate a ship's hull, that effect combined with the resulting explosion could be pretty devastating.

      Delete
    4. Bear in mind that we have no idea whether the torpedo is contact-fused or proximity fused for under-hull explosion, as most/all Russian torpedoes are. If it is proximity fused, as would seem likely, then the destructive power is simply from the size/type of warhead, like any other torpedo.

      Shadow, above, claims the torpedo has a HESH warhead but I've been unable to verify that as yet.

      Delete
  7. CNO,

    Although not directly relevant to your point about kinetic energy, your article showing the formulae we learn in high school physics/science to explain things shows a growing worry in western/American society- the growing tendency of people to avoid being educated/anti intellectual.

    It affects so much- minds become less disciplined, less thoughtful, less open to ideas. Just look here- without your article, people would still be writing arguements, thinking it was simply yourt word against theirs, and thinking their word/opinion was of equal weighting as yours.

    But back to your article, thanks for thoughfully explaining each stage. It was very enlightening.

    Andrew

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    1. That's a valid observation. We've forgotten how to analyze and, instead, fall back on assumptions and feelings - most of which are wrong!

      If you'd like to try this yourself, it would be informative to compare the KE of, say, a battleship's 16" shell to the torpedo. I don't have the time but perhaps you'd like to calc the KE of the battleship shell. All you need is to find the weight of a shell (somewhere around 2200 lbs) and velocity (exit velocity from the gun would be good enough for our purposes), make the proper unit conversions to metric, and do the math.

      If you want to do this, let me know what you find.

      My assumption is that the KE of a shell would be massively larger than a torpedo but, as I just said, assumptions are often wrong!

      Delete
    2. From NavWeaps data on 16" Mark 7:

      AP round: 1225 kg, muzzle.V= 762 m/s
      KE= 356 MJ, HE-charge: 18.55 kg (=77.6 MJ for TNT)

      HC round: 862 kg, muzzle.V= 820 m/s
      KE= 290 MJ, HE-charge: 69.67 kg (=291 MJ for TNT)

      Delete
    3. Outstanding! So, we've got a battleship shell with an impact KE of around 300 MJ versus a supercavitating torpedo with a KE of around 13 MJ. The torpedo isn't even in the same realm!

      We need to be real cautious about looking at energy releases for shells. The explosive power of shells is hugely magnified by the compression of the explosion due to the heavy walls of the shell. I'm way out of my field, here, but that's why a battleship shell with, nominally, a fairly small explosive charge produces an effect far larger than, say, modern missiles with bigger warheads. But, that's a topic for another time.

      The evidence is pretty clear that a supercavitating torpedo is not going to produce much of an impact just due to its KE. Now, the warhead explosion is a different story!

      Good work! Kind of makes you want to go out and analyze all kinds of naval stuff, huh? You know, like the Navy should be doing but seems not to? Recall the Navy's surprise upon finding out that the SH-60 helo couldn't safely tow the MCM equipment? Obviously, no one bothered to do any calculations on that before proceeding with the program. What an embarrassment!

      Delete
    4. "The explosive power of shells is hugely magnified by the compression of the explosion due to the heavy walls of the shell."

      Is there a source for that? That makes no sense. You can't "gain" energy by performing work on the shell casing unless you intend on starting a nuclear chain reaction. What do you mean by "explosive power"?

      It's true that you're transferring a great deal of the chemical energy of the explosives to the splinters by confining the detonation within the shell casing, but splinters were more of a "nuisance" than a deadly threat - to the ship itself that is. The bursting charge is really just there to keep the energy within the target as much as possible instead of having the shell pass through the target. Friedman's Battleships makes it very clear that over-penetration was as much of a concern as penetrating the target in the first place. This statement appears to be a good example of the dangers of romanticizing the past.

      Pound-for-pound, shells are generally the least damaging of bombs, mortars, torpedoes, and missiles because they need to be able to survive being shot out of a barrel, but that also gives shells an inherent advantage in terms of penetrative power. Sure, in some cases the penetrative power of a shell may lead to a larger effect on target than something with a bigger warhead and less penetrative power, but that's not what you stated above. There are many reasons for using a gun over missiles, bombs, and torpedoes but putting the maximum number of joules/kilogram on target isn't one of them.

      Delete
    5. This is largely outside of my field but, yes, the heavy walls of shells "magnifies" the explosive effect. No, you don't gain energy but in an unconfined explosion the energy is "gradually" released and dispersed - gradual on a very short time scale. For a heavy walled shell, the energy is confined, pressures from the burning gases build, and when the walls finally burst the energy is more concentrated. This is why a battleship shell scoops out huge craters in the ground when a missile, with a larger warhead, produces a much smaller crater.

      An expert in the field would probably take issue with the technical aspects of my explanation but the gist of it is correct.

      I don't have a ready reference but this is something I've investigated and verified many times because, like you, I initially was baffled by the seemingly small burst charge of a large shell that clearly had an explosive effect all out of proportion to its charge weight.

      If you're going to attempt to make a statement like "shells are generally the least damaging" then you'll have to explain the magnitude of the craters they make versus other types of munitions.

      This is one of those issues that isn't debatable - it's a simple fact; a fact that may not be known to you, perhaps, but a fact nonetheless. I'm not going to spend time "debating" a fact. If you have doubts, I encourage you to research it for yourself - I already have. I'm also not going to allow incorrect statements to be posted. I'm in the business of disproving "common knowledge" so be sure anything you say is backed up by verifiable data!

      Delete
    6. "This is why a battleship shell scoops out huge craters in the ground when a missile, with a larger warhead, produces a much smaller crater."

      Which is more powerful, a Grand Slam or a MOAB? The GBU-43/B MOAB weighs 21,600 lbs and is filled with 18,700 lbs of explosives. The Grand Slam weighed an even 22,000 lbs but only contained 9,136 lbs of explosives. The MOAB has a 2,900 lbs aluminum case. The Grand Slam had an approximately 9,000 lbs cast iron case.

      It depends on what you want to do. The Grand Slam was designed to penetrate up to 40 m of earth - it needed that case to do it - just like the 16” AP Mark 8 shell needs a 2,650 lbs case to penetrate another battleship's armor. The Grand Slam is optimized to propagate a blastwave through the ground, thus the nickname of the “Earthquake Bomb.” The MOAB is a daisy-cutter, reportedly having a “blast radius” of 500 feet. It’s optimized to propagate a blastwave through the atmosphere. It generates enough overpressure to damage light structures in a 845 foot radius.

      http://meyerweb.com/eric/tools/gmap/hydesim.html

      Neither can do what the other can so it’s debatable which is more “powerful.” What is not debatable is that the MOAB has twice the chemical potential energy of the Grand Slam. If you buried the MOAB at the depth the Grand Slam penetrates to, it would be twice as damaging.

      “If you're going to attempt to make a statement like "shells are generally the least damaging" then you'll have to explain the magnitude of the craters they make versus other types of munitions.”

      First, I said “pound-for-pound….”

      Second, I just gave a good example of how the size of the crater only matters if you care about the size of the crater.

      Third, your own calculations show that it’s extremely inefficient to make up for explosive mass with velocity. The reason is because drag also scales with the square of velocity, and the power to overcome that drag scales with the cube of velocity.

      Moreover, with respect to torpedos, supercavitation largely overcomes the skin friction component of hydrodynamic drag but not the pressure component.

      Delete
    7. “like you, I initially was baffled by the seemingly small burst charge of a large shell that clearly had an explosive effect all out of proportion to its charge weight”

      Except I’m not baffled because I understand the physics of what’s going on.

      A 1,255 kg 16” AP Mark 8 shell at a muzzle velocity of 739 m/s has 343 MJ of KE, although it reaches a minimum velocity of 474 m/s at 32000 m (141 MJ). The bursting charge of the Mark 8 is 18.55 kgs of Composition D. I can’t find the TNT relative equivalence factor (REF) of Comp. D, but it’s probably about 1.33 (the REF of Comp. B and Comp. C of that era). Therefore the chemical potential of the Mark 8 is approximately 103 MJ (24.6 of TNT). This means that the maximum energy that the Mark 8 could transfer to an enemy vessel or the ground is 446 MJ.

      Still, 446 MJ is a lot of energy, about 107 lbs of TNT in fact. If the shell buries itself in the ground before exploding, all of that energy is transferred into the earth. Also consider the fact that asteroids don't contain any explosives and yet make very large craters. You, however, are implying that you believe that if we dug two 25 foot-deep holes, put the shell in one and 107 lbs of TNT in the other, covered them, and detonated them, the crater made by the shell would be much bigger. That’s frankly, absurd.

      “For a heavy walled shell, the energy is confined, pressures from the burning gases build, and when the walls finally burst the energy is more concentrated.”

      You ARE correct that the detonation velocity of a confined explosion is higher (usually 25-40%) because the pressure is higher than for the same unconfined explosion, but that doesn’t hold true for the energy. You are ignoring conservation of energy and momentum. The 18.55 kg bursting charge has to shatter and displace the 1200 kg casing before it can do any work on it’s surrounding environment. That takes a lot of energy and you don’t recover the energy needed to shatter the casing in the KE of the splinters. The ability of an explosive to fragment its casing is related to the detonation velocity and is quantified as its brisance. In simpler terms, this is why some explosives are called “cutting” charges (high-explosives) while others are called “pushing” charges (low-explosives). Brisance does not equal the total work capacity.

      “I'm also not going to allow incorrect statements to be posted. I'm in the business of disproving "common knowledge”

      Disproving “common knowledge” doesn’t amount to much if it’s based on a misunderstanding of high school physics. See, for example, the current plague of flat-earthers. Sometimes those of us who picked up a slide-rule instead a rifle know what we’re doing. You often act like we’re all idiots. We’re not.

      - Caliber Curious

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    8. Curious, you appear to have some understanding of physics but clearly do not have an understanding of explosive behavior. Not surprising, the two are not identical and applying simplistic physics to explosions is inappropriate.

      You are also looking at energy balances rather than explosive effects. I described the difference between the two but I'll try again. Explosive effects are the damage inflicted on the target. The magnitude of those effects is due, in part, to the energy available for release and due to the behavior of the explosive and its "container" (the shell and other modifiers). Thus, conceptually, two explosives of identical weight and type ought to produce the same effects regardless of their container or modifiers, one would think. However, the container can amplify the effects (damage). For example, a shaped charge can produce more effect then a simple pile of explosive of equal weight detonated next to the target. Another example is the heavy walled shell, as I previously mentioned.

      An uncontained (or lightly contained) explosion dissipates its energy "gently" while a contained explosion (or shaped/directed explosion) dissipates its energy "violently".

      You offer some useful information so I won't delete the comment but I will note for the benefit of other readers that your discussion is misleading.

      You've stated your piece so leave it at that unless you can provide some actual and relevant references.

      Delete
    9. I’ve explained how your assertion is true, but not in the way you believe. Even the Wikipedia articles for detonation velocity and brisance are sufficient to show this. You are misleading your readers by not distinguishing between different types of effects on target. You can’t shatter a shell casing or shape a liner into a jet or efp for free. That’s fine if those are the effects that you want or need, but sometimes it’s better to push bulkheads and framing apart within an entire section of a vessel than cut or perforate them in a few isolated places.

      My point is merely that it’s not always true that a missile is less effective than a shell of the same weight just because the missile produces a different effect on target. It’s not a zero sum game.

      - Caliber Curious

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    10. The statement stands. A heavy-walled shell produces a bigger effect than a thin-walled missile of greater warhead weight (within some upper limit) against the kinds of targets commonly considered for naval land attack.

      Sure there can be specialized effects that naval shell is less effective for but those are uncommon. In fact, I'm hard pressed to think of a target where a 16" shell isn't a better, more effective choice. There probably is, somewhere, but I just can't think of it. Can you think of any?

      Delete
    11. "Sure there can be specialized effects that naval shell is less effective for but those are uncommon. In fact, I'm hard pressed to think of a target where a 16" shell isn't a better, more effective choice. There probably is, somewhere, but I just can't think of it. Can you think of any?"

      Unarmored and lightly armored ships. Infantry and light vehicles in the open. Attacking SAM sites and counter counter-battery fire (i.e., going after counter-battery radars). Really any target for which a significant degree of penetration is not required and/or an area effect is desired.

      In all of these cases a shell is a sub-optimal munition, but in many cases a gun is an optimal delivery system for its accuracy, time-to-target, sustained rate of fire, and cost to the extent that shells do not require guidance at reasonable ranges. I believe that naval gunfire is the best option for many naval fire support missions but because of the gun and not the shell.

      We have to be careful that we don't make the right decisions for the wrong reasons. We can learn the right lesson after making a wrong decision. We might learn the wrong lesson after making the right decision for the wrong reason.

      - Caliber Curious

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    12. "Unarmored and lightly armored ships. Infantry and light vehicles in the open. Attacking SAM sites and counter counter-battery fire (i.e., going after counter-battery radars)."

      Those are ideal targets for shells! Shells are cheap, can't be electronically degraded or decoyed, are all weather capable, and can't be shot down (theoretically, there is C-RAM but no one has demonstrated the ability to shoot down naval shells). Ideal!

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    13. "Those are ideal targets for shells! Shells are cheap, can't be electronically degraded or decoyed, are all weather capable, and can't be shot down (theoretically, there is C-RAM but no one has demonstrated the ability to shoot down naval shells).”

      These are also true of any bomb or missile following a ballistic trajectory. For rockets, guidance to apogee is generally sufficient to correct for variations in motor thrust and establish the correct ballistic trajectory. This adds expense, of course, but don’t forget that 16” barrels were only good for 290-350 rounds.

      http://www.dtic.mil/dtic/tr/fulltext/u2/a367940.pdf

      At 32000 meters a 16” shell is only moving at 474 m/s (mach 1.38), and even the muzzle velocity was only 762 m/s (Mach 2.22). Going much faster in a rifled barrel of that size starts becoming problematic due to excessive wear. As soon as a smooth bore and/or sabots are needed, guidance is also needed and the shell starts losing its cost advantage over missiles. Short-range ballistic missiles are capable of much higher speeds (mach 3+). There is no reason that a missile warhead couldn’t be, in essence, a 16” naval shell if you’re worried about C-RAM. This would be a pretty large SRBM (significantly larger than a 26" shell+powder charge due to the tyranny of the rocket equation), but you also wouldn’t need the barrels, elevation and traverse mechanisms, or ammunition handling mechanisms.

      “ Ideal!"

      Except they're not ideal. Don’t get me wrong, there are plenty of reasons to use shells DESPITE their inefficiencies, but shells haven't even begun to approach the minimum recommended explosive mass ratio for area-effects (25%) until the last few years. This is common knowledge.

      http://nigelef.tripod.com/wt_of_fire.htm

      "The following table shows the percentage and numbers of fragments of different sizes for different percentages of HE weight in 25-pdr shells, optimum anti-personnel fragmentation comes from shells with HE content at least about 25% of total weight, this was not achieved in WW2. However, the amount of fragmentation varies quite significantly with the power and violence of the explosive used, which also affects its destructive effects."

      “Most British field artillery shells used standard engineering steel, '19-ton' yield strength; in contrast the US used '23-ton'. Using normal as opposed to high strength steel made it easier to produce shells. However, it also meant that shell walls had to be thicker to survive firing stresses (assuming similar safety margins), which left less volume for explosive filling. One rule of thumb is that 19 ton steel allows 7% HE fill while 23 ton permits 15%.”

      "Using a standard target of 'men crouching in (British standard) slit trenches', a reasonable approximation of relative effect was the square root of the weight of explosive filling."

      If shells are the wunder-weapon you claim, why aren't bombs constructed like shells? Why do bombs typically have HE mass fractions of 50% or higher? What would a bomb lose by being constructed like a shell? Research these questions and I think you'll learn something.

      - Caliber Curious

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  8. I'm not sure kinetic energy and explosive energy is a direct comparison. Yes, they are measured is the same units, but kinetic energy is directed toward the target while explosive energy acts in all direction. The way a high speed torpedo would act upon a target would be somewhere between a traditional torpedo and an artillery shell....or so I'd assume.

    MM-13B

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    1. I'm sure a direct comparison of kinetic and explosive energy effects is not rigorously correct. However, I'm not an expert in the field and, absent an expert, it at least provides a crude basis of comparison that we can simplistically look at. Better than nothing, in other words.

      For instance, it allows us to conclude, with a fair degree of certainty, that the suggestion that a supercavitating torpedo will vaporize its target from KE alone, is wrong - and that was the point of the exercise.

      If you have a better means of comparison, I'm all ears!

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  9. At, Caliber Curious
    So what's the hull steel thickness of a modern destroyer say a Bruke?
    You are doing all these calculations but you have to take in mind that modern ships don't have armour like ships in WWII

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    1. That’s precisely the point. A shell that is designed to penetrate armor is likely to overpenetrate a modern ship without exploding. Battleship superstructures were often lightly constructed by design so that AP shells would pass through without exploding at closer ranges where trajectories are flatter. There were heated and fascinating discussions about the use of AP vs HE shells and fewer, heavier guns versus more, lighter, faster-firing guns in the big-gun era because of the overpenetration problem and difficulty of constructing reliable fuzes. Modern fuzes might solve that problem, but missiles can have an even higher explosive mass fraction than HE shells and have no issues penetrating modern vessels.

      Another constructive comparison is the difference in explosive mass fraction of mortar bombs vs artillery shells of similar diameter (e.g., 120mm mortar bombs vs 127mm shells). The mortar bombs have higher explosive mass fractions because they experience much less acceleration during firing and are often fin stabilized. If you don’t need a heavy case (e.g., for penetration or generating shrapnel), there’s little point in having one.

      - Caliber Curious

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  10. About that VA-111 Shkval warhead again, all Russian sources state the explosive as "Фугас" , witch means HESH, and early versions were non guided, later versions do not have a guidance system but rather a auto pilot system witch is programmed just before launch.

    And its not the only torpedo to have one, here is a diagram of the MU-90 impact torpedo, see the shaped charge

    https://qph.ec.quoracdn.net/main-qimg-0d80098b748dea85ae0e492221afe805-c

    But its one thing if you've being hit by a vehicle traveling at 29 knots or 200 knots ;)

    So basically, for a modern warship to be hit by a torpedo with a shaped charge would be pretty unpleasant.

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    1. A BROACH warhead might be even better.

      https://en.m.wikipedia.org/wiki/BROACH_warhead

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    2. Sure, the problem here is that because torpedoes are basically niche weapons serving only one purpose they're development cycle is longer compared to other weapon systems.
      So we have to wait for the next generation of torpedoes that shall replace the current ones.
      BTW what are the life cycles of modern torpedoes, i am sure its above 10 years but maybe 20 ??

      Delete
  11. And here's a good diagram of the Shkval , ya'll decide what the warhead looks like

    http://blog-espion.fr/wp-content/uploads/2011/05/torpille_Shkval_2.jpg

    ReplyDelete

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