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posted by Fnord666 on Wednesday October 25 2017, @08:47PM   Printer-friendly
from the faster-plinking dept.

The Navy plans to fire 5-inch diameter non-explosive projectiles from deck-mounted railguns:

The Navy plans to fire a high-speed, long-range rail-gun Hypervelocity Projectile from its deck-mounted 5-inch guns to destroy enemy drones, ships, incoming missiles and even submarines, service officials said.

The effort is led by a special Future Naval Capability program.

Navy officials say the program is leveraging commercial electronics miniaturization and computational performance increases to develop a common guided projectile for use in current 5 inch guns and future high velocity gun systems. The HVP effort will seek to increase range and accuracy of the 5-Inch Gun Weapon System in support of multiple mission areas, service developers told Warrior.

Developed initially for an Electromagnetic Rail Gun next-generation weapon, The Hyper Velocity Projectile, or HVP, can travel at speeds up to 2,000 meters per second when fired from a Rail Gun, a speed which is about three times that of most existing weapons.

BAE Systems Hyper Velocity Projectile. 5-inch gun. Found at NBF.

Related: U.S. Military Increasing Development of Directed Energy Weapons
U.S. Navy's New Mach 6 Electro-Magnetic Railgun Almost Ready for Prime Time


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  • (Score: 2) by c0lo on Wednesday October 25 2017, @09:20PM (9 children)

    by c0lo (156) Subscriber Badge on Wednesday October 25 2017, @09:20PM (#587573) Journal

    is trying to figure out a way to sell more of them...

    Well, if you shoot enough of them, some may ht the target. You only need to buy enough shooters.

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  • (Score: 2) by bob_super on Wednesday October 25 2017, @10:36PM (8 children)

    by bob_super (1357) on Wednesday October 25 2017, @10:36PM (#587603)

    That's my main question: how many rounds before you need to change the barrel ?

    • (Score: 2) by frojack on Wednesday October 25 2017, @11:24PM (6 children)

      by frojack (1554) on Wednesday October 25 2017, @11:24PM (#587612) Journal

      Thousands. The sabot can be made of non-abrasive material.

      Actually less wear and tear on the barrels than regular rounds which have to engage the rifling in the barrel in order to spin them.

      --
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      • (Score: 4, Informative) by c0lo on Thursday October 26 2017, @02:41AM (5 children)

        by c0lo (156) Subscriber Badge on Thursday October 26 2017, @02:41AM (#587676) Journal

        Thousands. The sabot can be made of non-abrasive material.

        Actually less wear and tear on the barrels than regular rounds which have to engage the rifling in the barrel in order to spin them.

        Correction needed. Wikipedia on railgun design [wikipedia.org] says:

        Currently published material suggests that major advances in material science must be made before rails can be developed that allow railguns to fire more than a few full-power shots before replacement of the rails is required.

        And here's how a railgun firing looks like [wikipedia.org] - I suspect the energy consumed in this one show to be in the MJ range, perhaps higher.

        ---

        My thoughts - the hyper-velocity comes with some costs:
        1. conductivity - currents are in the thousands of amps, the ohmic losses (heat) goes with the square of the current;

        2. until one gets high temperature superconductors, I don't think anything else but copper can do. Which is is a mecanical problem: copper is very maleable thus low resistance to friction wear and deforms easily - do I need to draw the picture what will happen with a very minor deformation when it is hit at well in excess of 2000m/s? Can you imagine the repulsive force developeped between the two rails?

        3. friction during the sliding of the projectile over rails. Friction will be lower for lower area of contact between the projectile and the rails, but... low area of contact means high current densities, which means the contact area overheats and the current->kinetic energy efficiency drops. Higher area of contact means lower loss do the resistivity but the friction increases.

        4. huge magnetic field variations in a short time - losses in eddy currents induced in anything metallic around? How about the arcing due to the extreme voltages imposed by the necessary magnetic field variation?

        Those huge copper bars, mounted as rigid as possible in some very strong frame - preferable non-metallic -... expect them to heat quite high during the firing and the wear to be non-negligible.

        One thing that can be done to increase the lifetime of the rails - use soft metals for the projectile casing, with low melting/boiling point and as good conductivity as possible - aluminium would be a good candidate.
        The effect that I'd expect - in the first part of the acceleration, the ohmic heating in the contact area will be quite high. I expect the superficial layer of the sabot to melt (or even evaporate), "lubricate" the rails and decrease the wear on the rails without a significant drop in the contact conductivity.
        But... doing so may decrease the accuracy, I'm not sure they can afford the trade-off - what good is a long-lived long range/high energy cannon if the accuracy is shit?

        --
        https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
        • (Score: 3, Informative) by frojack on Thursday October 26 2017, @03:22AM (2 children)

          by frojack (1554) on Thursday October 26 2017, @03:22AM (#587689) Journal

          Uhmmm, in case you need help with your reading comprehension, this isn't about shooting a railgun.

          Its about shooting a sabot jacketed projectile out of a 5 inch gun with the same (or similar) powder charge that they fire conventional shells.

          They aren't converting these guns to rail guns, they aren't going to shoot anything all that much faster out of the barrel than they already shoot, (beyond the speed improvement they would get by firing a lite weight projectile).

          Its no more barrel wear, and because its a sabot round (google that) your don't even have to engage the refiling in the tube with anything except plastic, the projectile has its own fins for spin and stabilization.

          Go read about the 5 inch MK 45 gun: https://en.wikipedia.org/wiki/5"/54_caliber_Mark_45_gun [wikipedia.org]

          --
          No, you are mistaken. I've always had this sig.
          • (Score: 2) by c0lo on Thursday October 26 2017, @04:43AM

            by c0lo (156) Subscriber Badge on Thursday October 26 2017, @04:43AM (#587703) Journal

            Uhmmm, in case you need help with your reading comprehension,

            Reading time is what was missing.

            --
            https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
          • (Score: 0) by Anonymous Coward on Friday October 27 2017, @03:15PM

            by Anonymous Coward on Friday October 27 2017, @03:15PM (#588249)

            Uhmmm, in case you need help with your reading comprehension, this isn't about shooting a railgun.

            The error is in the summary, where it says "The Navy plans to fire 5-inch diameter non-explosive projectiles from deck-mounted railguns."

        • (Score: 0) by Anonymous Coward on Thursday October 26 2017, @04:04PM (1 child)

          by Anonymous Coward on Thursday October 26 2017, @04:04PM (#587861)

          Ignoring your misreading of the issue (see other comment)...

          How about a disposable conductive liquid oozing from the rails? The obvious is a really thin layer of seawater. The projectile glides on the water. The water boils off, removing the heat as it does.

          Accuracy is no trouble with guided ammo, which I think these are. (slightly, like a guided artillery or mortar shell)

          • (Score: 2) by bob_super on Thursday October 26 2017, @04:28PM

            by bob_super (1357) on Thursday October 26 2017, @04:28PM (#587868)

            > The obvious is a really thin layer of seawater. The projectile glides on the water. The water boils off,

            Leaving behind salt, which you have to wash off quickly before it destroys everything.

    • (Score: 2) by c0lo on Thursday October 26 2017, @02:44AM

      by c0lo (156) Subscriber Badge on Thursday October 26 2017, @02:44AM (#587679) Journal

      A very few [soylentnews.org]

      Which is good for the business, isn't it?

      --
      https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford