I caught the orange man talking on the radio, as I am not american I knew it was going to be something stupid but this? I thought it was a joke, an onion like thing, but nooooo. What sealed it is when in the very speech about the new 100x battleships, trump stated that he did not know why the us stopped using battleships…

  • M0oP0o@mander.xyzOP
    92·
    8 days ago

    The world is, and I know this might be a shocker, round.

    Railguns when tested have an odd issue in that they shoot things real fast, and therefor a much flatter ballistic trajectory. Now this is good! if the curve of the earth did not put a fuck load of water between the railgun and the target. In fact due to physics (you know that thing that we are both clearly experts in) you end up with a big old dead spot in your range tables (more so with high sea states) where the railgun’s dart will hit the waves on route to the target and although moving wicked fast the uncaring ocean will still stop or really change the darts course. This changes when you range out far enough that the ballistic trajectory curves enough but at those ranges accurate guidance is another issue (this was found out in 2019).

    So yeah according to physics shooting a thing at over 8000 km/h out of a tube means a flatter then needed trajectory for mid range (in ship to ship context) and when you get out to the full range you are talking 180 km or so, and at that point even the super fast darts are avoidable/hard to get on target.

    • theunknownmuncher@lemmy.world
      12·
      8 days ago

      This is nonsense, and the source you linked does not support or even mention anything about what you’ve claimed about trajectories. Did you just hope no one would actually read it? It does, however, talk about the sustainability problems with maintaining the railgun as well as the benefit of simply using the projetile developed for the railgun in conventional guns. From your source:

      As the Navy was developing EMRG, it realized that the guided projectile being developed for EMRG, which weighs about 23 pounds, could also be fired from 5-inch and 155mm powder guns. When fired from EMRG, the projectile reaches hypervelocity (i.e., Mach 5+) speeds, and thus came to be known as the hypervelocity projectile (HVP). When fired from a power gun, the projectile flies quickly, but not as quickly as it does when fired from EMRG.

      “We thought rail guns were something we were really going to go after, but it turns out that powder guns firing the same hypervelocity projectiles gets you almost as much as you would get out of the electromagnetic rail gun, but it’s something we can do much faster,” [then-Deputy Secretary of Defense Robert] Work said.

      The trajectory of any projectile, including the shot of a railgun, follows an elliptic ballistic curve.

      There’s no such thing as a dead spot in the range. You just aim up.

      • M0oP0o@mander.xyzOP
        33·
        8 days ago

        Yes, for longer range shots. For the middle of your range, you can’t “aim up” that would not hit the target at the speeds needed. Lobbing rounds with a railgun is mostly worthless and can be done, as you have said, with a normal naval gun. So take your diagram (that has the labels wrong) and compare to an old one, from when battleships where still in use. See you are assuming that all ballistic curves are the same but the old 16 inch guns (for example) shot at 762 m/s vs the railgun that shoots at 2,220 m/s so the railgun will be more “flat” then the naval gun. Still a curve yes, but one that is now awkward when at sea. From what I was seeing this issue can be mitigated by moving the gun higher on the ship (its not by much the dart clips the waves) but that introduces new issues. The distance before something is “lost” over the horizon at sea is between 5 and 10 km (based on the height of the ship), at this range the railgun is still mostly going “straight” (its not but the drop is not enough yet). So if you want to hit something say 12 km away (in range of normal naval guns fyi) you would need to shoot so high that you would be putting the dart into a sub orbital trajectory and without guidance be lucky to hit anything (and good luck making a system that can withstand air at sea level when traveling at mach 6).

        • theunknownmuncher@lemmy.world
          61·
          8 days ago

          would not hit the target at the speeds needed

          As a projectile falls, it is accelerated by the force of gravity and gains speed.

          you would need to shoot so high that you would be putting the dart into a sub orbital trajectory and without guidance be lucky to hit anything

          The projectile fired by the railgun is GPS guided. What you’re describing is literally the exact situation it is designed for. It is intended to leave Earth’s atmosphere.

          The GPS-guided projectile will exit the launcher at approximately 2500 meters/second. On the way to its target, the projectile would leave the Earth’s atmosphere, making it less susceptible to jamming or interception, and minimizing interference with friendly aircraft upon re-entry into airspace.

          https://www.globalsecurity.org/military/systems/ship/systems/emrg.htm

          You’re simply incorrect about how any of this works.