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US Navy installs experimental rail gun on JSV for trials.

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  • #16
    Originally posted by desertswo View Post
    With or without the sabot?
    Don't know. The information disclosed on the gun isn't that specific:

    Railgun Systems

    I just did some simple math to get an educated guesstimate.

    32 MJ. Mach 7. Speed of sound at sea level is 340 m/s. KE = 1/2 MV^2

    That gives a projectile weight of 11.3 kg. I assumed a light weight sabot of 1-2 kg, leaving a ~10 kg projectile. From the color and the reflectance the sabot looked to be aluminum. Also, I remember in one interview, Admiral Klunder said something about a 10 kg projectile, so it seemed to make sense.

    Maybe it was this interview:

    Last edited by citanon; 11 Feb 15,, 20:13.

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    • #17
      Originally posted by SteveDaPirate View Post
      I would expect the "dart" to be about as dense as they can make it in order to put the maximum amount of energy in the most aerodynamic profile. Depleted Uranium seems like a likely candidate as it combines very high density with a few other useful properties as a penetrator. A certain portion of the volume would also have to be devoted to whatever control mechanism the lab guys have devised that can survive the acceleration to Mach 7 in a fraction of a second.
      Yes, DU would make the most sense, with tungsten coming in a distant second; I imagine it would be something similar to the M829E4 round that the M1A2 tank fires, with a sub-caliber DU projectile, only without the propellant charge. I'm guessing the sabots would probably have to be made out of a low-friction composite material that wouldn't interfere with the electromagnetic impulse from the gun?
      "There is never enough time to do or say all the things that we would wish. The thing is to try to do as much as you can in the time that you have. Remember Scrooge, time is short, and suddenly, you're not there any more." -Ghost of Christmas Present, Scrooge

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      • #18
        From what I understand the sabot is metallic and in electrical contact with the rails. The friction is solved via vaporization of the contacting layer on the sabot into plasma

        The round is actually guided and fuzed for dispersal of impacting fragments.

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        • #19
          Is that vaporizing contacting layer what creates the substantial muzzle flash when the projectile exits the barrel?

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          • #20
            I think so.

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            • #21


              From what I understand, in the case of the Navy's railgun, the sabot is the armature.
              Attached Files
              Last edited by citanon; 12 Feb 15,, 10:53.

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              • #22
                Originally posted by citanon View Post
                [ATTACH=CONFIG]39188[/ATTACH]

                From what I understand, in the case of the Navy's railgun, the sabot is the armature.
                Ah, that makes sense; I figured the sabot would either have to be magnetically inert, or it would somehow have to contribute to the electromagnetic propulsive force from the gun.
                "There is never enough time to do or say all the things that we would wish. The thing is to try to do as much as you can in the time that you have. Remember Scrooge, time is short, and suddenly, you're not there any more." -Ghost of Christmas Present, Scrooge

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                • #23
                  Originally posted by citanon View Post
                  [ATTACH=CONFIG]39188[/ATTACH]

                  From what I understand, in the case of the Navy's railgun, the sabot is the armature.
                  Thanks for posting that. Generator and motor armatures are something I understand well. When the rail gun is placed in that context, it makes perfect sense and is rather elegantly "simple."

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                  • #24
                    Originally posted by citanon View Post
                    [ATTACH=CONFIG]39188[/ATTACH]

                    From what I understand, in the case of the Navy's railgun, the sabot is the armature.
                    A couple of questions occur, firstly does this mean the armature is completely vaporized or are large pieces of shrapnel sent down range as well? This might not be such an issue at sea but I could see how it might be problematic on land.

                    Secondly I presume the long term goal would be to scale the whole system up so it could be used for larger more conventional projectiles. If this is so will current guidance electronics (e.g. Excalibur etc) be able to cope with both the acceleration forces and the EMP effects?

                    I just can't picture the Navy wanting to arm these things exclusively with 'dumb' projectiles, at least not when your planning on engaging targets 100 klicks or so away.
                    Last edited by Monash; 13 Feb 15,, 06:37.
                    If you are emotionally invested in 'believing' something is true you have lost the ability to tell if it is true.

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                    • #25
                      Originally posted by Monash View Post
                      A couple of questions occur, firstly does this mean the armature is completely vaporized or are large pieces of shrapnel sent down range as well? This might not be such an issue at sea but I could see how it might be problematic on land.

                      Secondly I presume the long term goal would be to scale the whole system up so it could be used for larger more conventional projectiles. If this is so will current guidance electronics (e.g. Excalibur etc) be able to cope with both the acceleration forces and the EMP effects?

                      I just can't picture the Navy wanting to arm these things exclusively with 'dumb' projectiles, at least not when your planning on engaging targets 100 klicks or so away.
                      From the videos you can see that the armature emerges mostly intact from the barrel. I'd imagine that one would want to stand well clear of the business end of the gun.

                      The Navy says the shells will be guided and fuzed, which boggles my mind given exactly the issues you raised. Don't ask me how they did it. Anybody who knows would probably have SEAL Team Six fast roping into his backyard for posting it on the internet.

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                      • #26
                        Id Hazard (Excuse the multiple pun) a guess that you'd need to see the acceleration of a powder shot vs a current shot. Solid State Electronics are a marvellous thing.

                        It looks as though the armature is designed to conduct current, carry the projectile (maybe even shield it from the current), and separate cleanly once clearing the barrel.

                        Fuck me I'd be staying well clear of the business end of any sort of artillery bloke!
                        Ego Numquam

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