Some Leviathan Numbers

Just to clarify the capabilities of those mass drivers, and note, this is back-envelope work.

So, we’re going to stick a big dumb projectile in the breech. By big, dumb projectile we mean a 2400 mm k-slug of soft iron (iron being cheap as dirt, and really, what it’s made of doesn’t matter all that much in this application), and we’ll call it a 2400 mm diameter cylinder, 4800 mm long. That’s 22 m3 of iron, massing 173 metric tons.

If we crank a Leviathan primary up to full power, we’re going to be sticking about 10.1 exawatts (usable) in the flash accumulators; that’ll accelerate that projectile at around 1.1 million gravities for close to a second, meaning it leaves the muzzle with a velocity of 0.036 c, i.e., in the low-relativistic regime. Impact energy delivered to the target is on the order of 2.4 gigatons.

This, needless to say, is way too much boom for almost all practical applications, and no-one routinely stocks that kind of k-slug or runs their mass drivers at that power level, not least because it’s gonna take enough time for the shipboard powerplant to put ten exawatt-seconds in the flash accumulators that you sure aren’t going to be able to fire one of those shots every second, or anything close enough to it to avoid being a big, fat, wallowing target. There are uses for Mighty Glaciers and uses for Glass Cannons, but there’s no use at all for something that’s both.

But if you happened to be interested in what the hardware could deliver if you wanted to comically overkill something with no means whatsoever of fighting back, there are your numbers.

 

6 thoughts on “Some Leviathan Numbers

    • Coilguns, technically.

      And while the big advantage of coilguns is that you can launch pretty much anything from AKVs to yeast, the most common load is plain old dumb k-rods, often plain iron because it’s cheap.

      The IN certainly has a plethora of specialty warheads which it can load and fire, various of which are usually carried by mission requirements and captains’ preferences, but with the energy-on-target that a dumb slug can deliver, strapping a fancy warhead to it for regular use is just gilding the lily.

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      • I’m also assuming that with navy coilguns there is also some interesting vector control trickery involved.

        Also, playing around with various internet calculators one can see that that same 10.1 Exajoules (typo in original or am I entirely incorrect? It’s been few years since my physics classes…) are sufficient to propel a 1 kilogram projectile to high-order relativistic regimen (ie. to about 0.997c, including gamma). Note that the interstellar medium would, at that velocity regimen, erode such projectile to harmlessness in just few weeks or months.

        Of course, Our Gracious Host noted that the limitations are in projectile acceleration so that those near-c projectiles are currently impossible. Still, probably a hot research subject given the obvious tactical advantages.

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    • I had written a reply to this, but it seems to have disappeared. Sorry for the double post if it resurfaces.

      Anyway, warheads seem like they’d be most useful for specialized things (at least two have been mentioned in nanofics past…) as in the general case it is hard for Big Dumb Slugs to get mission killed by point defense, and things like one-shot lasers or particle beams or plasma whatever devices would seem to be poor choices against the sorts of ship armor available (modulo comments I made in a thread some time past about the possible breakdown of thermal superconductivity in the face of ionization or lattice defects…)

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  1. it’s gonna take enough time for the shipboard powerplant to put ten exawatt-seconds in the flash accumulators that you sure aren’t going to be able to fire one of those shots every second, or anything close enough to it to avoid being a big, fat, wallowing target

    As per my (possibly incorrect) calculations in the last leviathan post, the pion drive running at cruising power levels produces ~16 exawatts of gamma radiation. Obviously, lots of that will radiate in the wrong direction, and harvesting any of it without cooking yourself with excess heat is hard, but not implausible. Do the eldrae have gamma voltaics?

    Cranking the engine up a bit but tapping the energy of all those extra charged pions via direct energy conversion instead of as thrust via a magnetic nozzle is also not a bad idea, and somewhat less magitechy. That’s a couple of extra exawatts right there, anyway.

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