Absalom wrote:Suederwind wrote:ShadowDragon8685 wrote:
I feel safe in saying that by the 2160s, even humanity almost certainly have effective accumulators which can suffice as small arms railgun power supplies. Remember, they have accumulators that can store enough juice for a hyperspace jump, after all.
I could imagine that they use ammunition made of a capacitor and a projectile, like we use ammunition made of a chemical propellant and a bullet. Accumulators would take too long to discharge, I assume.
The nice thing about the chemical propellants is that they last longer than a capacitor charge. Regardless of whether it's in the bullet or the magazine.
Yes, but the battery in the magazine can be left on a charger storage rack between issuing. Capacitor-caps on the end of each projectile could not, at least, not remotely as simply.
Absalom wrote:ShadowDragon8685 wrote:Suederwind wrote:I could imagine that they use ammunition made of a capacitor and a projectile, like we use ammunition made of a chemical propellant and a bullet. Accumulators would take too long to discharge, I assume.
I'd more expect that it would be part of the magazine. Using a capacitor as "brass" requires separate power for the brass extraction, it also means more moving parts and more things to go wrong.
It would probably just use the current extraction technology, which is tried & true.
It would not, because current extraction technology
requires gas actuation of a piston. You would need to either have a separate battery source on the weapon to electrically actuate the brass extractor, or siphon part of the capacitor discharge from the capacitor-cap. I do not consider either of these options as acceptable as
simply not needing to extract brass in the first place.
Obviously, you would still need some kind of manually-actuated lever to extract a projectile you did not want in the chamber that was in there, but except for that one purpose - and the purpose of rendering the weapon visibly safe by jamming a safe flag in the chamber and sticking out the extraction port - you wont need to use it.
Absalom wrote:Suederwind wrote:Each one will need to be electrically verified before being taken into combat - has it shorted at some point, has it started to go flat, etc, etc. That would be a logistical nightmare.
Well, chemical propellants needed to be keept dry in the age of blackpowder and guncotton. It was problematic, yes, but not that hard to handle. If those things are massproduced I assume such problems could be solved easily. For example: they could be charged before issued to the soldiers (or imagine a box of this kind of ammunition going off by accident or is shortened on its way to them).
That's not how capacitors work, if you want them to keep a usable charge then you need to keep them charging because they always leak a little. It's really just the huge ones that keep an impressive charge, and even for a magazine those would probably be
too large.
That's why you store the mags on some kind of charger rack that keeps them fed before you send them into combat. With sufficiently advanced technology, the leak should be so small that in any reasonable extended operation, the ammunition should be exhausted before accumulator charge remotely becomes an issue.
Absalom wrote:Suederwind wrote:Plus, a partial shot from a capacitor is likely to weld the projectile to the rails. You're not clearing that with rack-tap-bang. Whereas accumulators in the batteries will be far more reliable.
And what happens if a bullet is welded to the rails in your model? Most likely the same, I assume.
Yes, but my way is much less likely to result in a projectile welded to the rails. A magazine-sized battery will have room and budget for more diagnostic electronics than capacitor-caps will have, which means it will be better able to warn the user/prevent discharge if it is damaged. You'll also be analyzing the entire magazine's battery the moment you slot it in, rather than analyzing each cap-cap as it gets to the chamber
Absalom wrote:But, why would accumulators in the magazine be more reliable? The energy from those would need to charge a capacitor in the rifle anyway, if the railgun should work. On the other side, I have to admit, that I have no idea how big the capacity of such an capacitor should be for a railgun to work.
Depends on the projectile & speed. Take a look at
this Instructable. You can probably get the volume down a bit by using supercaps, but every electric gun project I've seen involved huge capacitors: you might be able to justify this sort of thing for the gun itself, but you want higher energy density for either bullets or magazines.
Here's a Hackaday article that touches on one project's cost for the capacitors involved: several thousands of dollars worth.
Remember, those are 2016 costs and tech, not 2160 costs and tech. Having super-duper awesome accumulator technology is a
prerequisite for hyperspace jumps, since not even the Loroi using fullerened antimatter (or something similar,) can produce enough peak output with two xboxheug reactors to do a hyperspace jump without charging the accumulators.
If you have accumulators that can fuel a hyperspace jump, you have accumulators that can fuel a railgun rifle.
Absalom wrote:At any rate, I imagine that a coil-gun system will (weight aside) be more practical: less rail erosion, the one eroding piece (innermost barrel) can always just be a replacable disposable part, and tack-welding need not be a credible concern (whereas it always will be for all of the current designs that I know of: you'd have to use single-use disposable wire rails to avoid it).
Whether it's rail or coil (and I believe it
will be rail by 2160; erosion is a mechanical problem that can be overcome,) the point is that when you go into a ground battle in the 2160s with a projectile weapon, it's as likely to be magnetically accelerated as propellant. And I think that the most optimal way to make a mag-rifle is going to be with a magazine-length battery in front of a stack of ferrous projectiles. (In front so you have that tiny bit more barrel length, because for a projectile weapon, an extra inch
does matter. (That's what she said.))
Absalom wrote:Anyways, trying to stick a capacitor in either the bullets or the magazine is a mistake: you want to use a
Flow Battery or MHD or similar technology to use a "fuel" stored in the bullets or magazine, in conjunction with a electrode pair (or comparable) in the gun, to charge up capacitors that are also in the gun. That way you only have to deal with one set of heavy & bulky capacitors (instead of a seperate set per bullet or magazine), leaving longer-term energy storage to a system better suited to it (batteries or equivalent).
The exact nature of the electrical equipment in question is probably not understood, or is only theorized, at present. I'm basing my understanding on that of Eclipse Phase: battery + projectile goes in = bullet goes out, very very fast. Propellant bullets are less damaging, but have more wizz-bang options available to them because there's not huge EMF to fry any wizz-bang option electronics.