Hi! Would it be possible to make a railgun firing molten metal instead of a solid projectile? The ''projectile'' would be a beam of molten metal made of molten steel inserted into a fully enclosed tungsten sabot through a hole in the sabot that is closed just before firing. At the end of the sabot there would be a tight corridor which would force the molten metal to be tightened into a beam just before the sabot is discharged causing the molten metal travel at many kilometers per second as a tightened beam. And would a molten metal beam offer any advantages when it hits the enemy ship when compared to a solid projectile? How would a solid 15 kg projectile traveling at 7km/s impacting the enemy ship differ from a centimeter wide ''beam'' of molten steel with the mass of 15kg impacting the hull of at 7km/s? Which would do more damage? And I have attached a picture of the molten metal firing railgun. And how would the molten metal act in space? Would it solidify quickly?
Answer It's possible, but liquids don't make good projectiles. This also isn't perhaps the best way to accomplish this, you really drew a very small amount of metal and a lot of stuff that accelerates with it. You'd also have to have something split that sabot open and make the beam, it won't just "stop" there. A sabot discharges with the projectile. Aside from the option of spreading damage over a line if they swept the beam pulse (it wouldn't be a beam, just a stretched projectile, which you could make with something like shotgun pellets as well as you could a liquid), there's really no advantage to having a liquid projectile. Any projectile you can think of will liquefy at the speeds you mention. A liquid metal in space...depends on the material. Mercury? Lead? Uranium? Open question about "how quickly." But it will evaporate to a degree on its way to the target, lessening the amount that hits the hull of your target ship.
Cleverly designed electrical discharge could probably do this better without a sabot. Some kind of electrical pulse accelerator putting smaller amounts into an electromagnetic lens or lens set. (Stretched out in a line of individual accelerators, each timed to add pieces to the stream.) That means more energy/mass in your weapon.
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