• mnemonicmonkeys
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      2 months ago

      Gun large enough to hit London. The barrel had to be so long that they built it into a hillside to keep it supported

      • CanadaPlus@lemmy.sdf.org
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        2 months ago

        Hmm. I’m guessing they had problems with getting enough propulsion going? The modern approach would involve some very synchronized stages, but WWII tech would make that difficult.

        Otherwise, this would be a pretty cheap way of doing the Blitz.

          • CanadaPlus@lemmy.sdf.org
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            2 months ago

            Yeah. Now it’d be easy to programmably trigger each charge on the order of microseconds or less, and we can make some pretty fast-shutting valves. Barrel wear is harder and would probably involve simulational fluid dynamics. More likely we’d just build a coilgun, which removes that issue very nicely, and uses similar control electronics.

            Of course, if you want to destroy a city there’s also nukes now, and anything else tends to either move or be very well protected. People have talked about this for space travel, but the trade-off between G-forces and length hurts at least as much as the rocket equation (despite being “only” quadratic instead of exponential).

        • sugar_in_your_tea
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          2 months ago

          Wouldn’t the modern approach largely use synchronized magnets? I suppose you could synchronize explosive charges, but that seems way more complicated than a rail gun.

          • CanadaPlus@lemmy.sdf.org
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            2 months ago

            Quite possibly. Synchronised coils are still a kind of stage, though.

            The downside of that approach is that you have to deliver a lot of electricity quickly. I’d still try it first, just because of the difficulties around protecting the barrel, and the much reduced moving parts count. I should also mention light gas guns, which mostly work like a normal non-staged gun but can get low-hypersonic muzzle velocities just by virtue of how quickly hydrogen or helium can expand.

            • sugar_in_your_tea
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              2 months ago

              It’s a lot easier to produce large amounts of electricity than explosives IMO, especially in war-time when your supply lines are all messed up. As long as you have batteries/capacitors available for your weaponry, you can get creative on how you charge them.

              • CanadaPlus@lemmy.sdf.org
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                2 months ago

                Yeah, but we’re not talking about lighting or space heating here. You need all that energy at once in a split second. Vacuum flywheels or superconducting loops are the usual go-tos for powering coilguns IIRC. The power electronics and switches (as opposed to the control electronics) also need to be able to handle significant current while still being fast.

                If it was that easy, normal stationary guns would be electrical, rather than using a primary and secondary explosive charge in precision-machined disposable casings.

                • sugar_in_your_tea
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                  2 months ago

                  Right, it’s not easy, but it’s generally a one-time cost, especially if it’s going to be in a well-defended area (e.g. the electrical bits would largely be underground to protect from bombs and help w/ heat control). So once you build the infra, you just need to be able to recharge it, and it’s pretty easy to create electricity even if your supply lines are cut off (burn whatever you have).

                  It certainly wouldn’t be practical for a mobile battery, but for something like this that just sits on a hillside, I think it would be quite practical. So not something the US would be interested in, but it would make a ton of sense for something like Nazi Germany where there are a ton of enemies within shooting distance.

                  • CanadaPlus@lemmy.sdf.org
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                    2 months ago

                    And enemies all exposed together in a fixed place, but somehow not reachable by normal weapons of mass destruction. That’s the real reason hillgun is noncredible at this point, even if you could figure out a way to protect the muzzle end well enough.

                    I said in another thread here that I’d go for coilgun first, so I don’t disagree. More for the resistance to wear or mechanical failure than because explosives are hard to come by, though.