Coilguns are pretty simple to make at that simple level, with railguns, AFAIK, being even simpler physically, but harder to make because of the more dangerous forces involved. The issue is that neither is up to chemical-ballistic standards as of yet.
Won't be too long. Size and logistics will be the bigger hurdles, I think. DARPA has an experimental coilgun mortar with 45 stages, and the U.S. Navy was looking/is looking into railguns for use as bombardment weapons on warships.
Basically, the forces and heat involved are just really, really silly. I'd imagine things with the thermal resistance to absorb it without partially vaporizing are too brittle to handle the physical blast.
Also true, but don't forget that the scraping action of the sabot as it moves along the rails, especially since the rails are gonna be getting pushed out, at least on a micro-level, from the projectile, where they're in contact as compared to in front of the projectile, is gonna be damaging the barrel.
Railguns are cheap, but logistically expensive. I've heard that coilguns are considered sensitive or finnicky or whatnot, but they're also reliable in a different sense than railguns are. Railguns are rugged, but you need new barrels basically all the time. Coilgun barrels are a lot more expensive to start with, and maintenance might be more necessary, but they're also far more reusable and will undergo a lot less wear, I suspect. Neither will be usable in small arms for a very, very long time, by which point these issues will be mostly solved, I suspect. (A railgun where the magazine and barrel are an integrated unit would be interesting)
It is very possible magnetic weapons will never be used for small arms.
My argument comes down to energy efficiency, at its root. A soldier can carry a limited amount of weight, so you want as much bang for your buck as you can get.
A gun is 30+% efficient. As in, you put 100X energy in, a bit more than 30X of that energy goes to propelling the bullet. The rest of the energy is lost to bullet friction on the barrel (approx 2%), to heating said barrel (30%), a percent or so to propellant not burning and the remainder stays in the hot gas once it leaves the barrel, so is wasted that way.
The longer the barrel, the more efficient it is, but the gain is less than the volume ratio. That's why is you shoot the same round out of two guns, only differing in barrel length, the longer barrelled gun will be more powerful. Larger cannons also have a better volume-to-surface ratio. High barrel diameter is also helpful because lower barrel friction is induced by sealing compared to the accelerating force. The force is proportional to the square of the barrel diameter while sealing needs are proportional to the perimeter by the same pressure.
Wikipedia uses a .300 hawk as an example at 32% efficiency. Now, I couldn't find the actual muzzle energy of a .300 hawk, because for some god-unknown reason they used a wildcat catridge as their example. But for the sake of simplicity and 'good enough', I'll take that as a standard efficiency.
That's pretty decent.
The DARPA coilgun mortar was 22% efficient.
That's not
awful, and it's not unusable for something you don't need to be lugging about by hand in a direct fight.
Can that be improved? Perhaps, but so far it hasn't, so I'm using that figure. Apples and oranges, but at least they're both fruit.
But energy storage is pretty heavy, particularly electrical energy. Chemical energy can be pretty good, which is why our civilisation is built on it.
A M855 5.56mm NATO round through a 20 inch barrel has a muzzle energy of 1974 J. A catridge weight, minus the bullet, is 12.31 - 4.02 = 8.29 g for 1974 J of energy delivered. 338.12 useful J per gram.
An alkaline D battery seems to have the most energy in it of the D batteries and a weight of 135g, according to
this site. It has 74970 J in it. At 22% effeciency that gives us 16493.4 J. That would give us 8.36 equivalent 5.56mm shots. 122.17 useful J per gram.
Quite a difference. I chose the D battery because that's the largest common battery I can think of that isn't, say, a car battery. Perhaps handheld coilguns would be like hellguns from 40k and attached to a backpack power source, but I've not looked at that.
Remember, that's using the 45-stage mortar, not any handheld coilgun, though I'm not confident enough to ballpark any figures for a lesser stage weapon. The coilgun in
this video (though it is just a hobbyist project and not representative) has an 'estimated efficiency of 1-3%'. I'm guessing that a handheld coilgun might get an efficiency somewhere between that and the mortar.
It's not really a fair comparison, being overly lenient towards the coilgun as it is, but hey, it's rough.
Energy isn't quite the same issue if you've got something like a battleship or a vehicle you can suck power from, so no doubt they'll end up on there sooner or later. It's also at that sort of scale the benefits of a magnetically accelerated projectile start coming about.
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When it comes down to it, what benefits would a magnetically accelerated weapon give your infantryman? Power isn't always a must for a soldier, because they dropped down to the 5.56mm from the more powerful 7.62mm round. It would weigh more. It'd probably be less sturdy. It might shock you if it gets damaged with a lethal voltage. rate of fire might be limited by how fast the capacitors could charge, but I'm less knowledgeable about electronics like that, so I couldn't say. A conventional gun probably has less
and more sturdy parts than a coilgun.
It would presumably fire a supersonic projectile. This would mean they would hear the supersonic cracks of your round, so the rifle wouldn't be silent. Modern metal baffle suppressors can reduce muzzle flash and noise without reducing velocity, so there's not a huge benefit going mag if that's your main concern.
You'll still have recoil. Sir Isaac Newton may the deadliest son of a bitch in space, but that's true on the ground as well.
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"But Gig," I hear you say. "What if energy storage and coilgun efficiency both improve?"
Well, they'd still have quite a bit to go before they matched conventional propellants. And even if they did... who says a better propellant for small arms won't be developed, either? After all, black powder gave way to smokeless powders.
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I'm not looking at railguns for small arms because carrying around more barrels as well as everything else is just an awful idea. Like coilguns but shittier.
TL:DR magnetic weapons suck at man scale
Also goddamn this post is longer than I expected. Did I fuck up any of the maths? Probably. It's all rough, anyway.
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Topic: Theoretical weapons (Burn all the things!) and other ideas (Read 100962 times)