Are Gauss Guns railguns OR coilguns?
 

I've seen shredders from GURPS Alpha Centauri described as Gauss weapons, a nomencalture which I assume originates from GURPS Ultra-Tech. (And I assume the answer I'll be getting is "yes.")

Funnily enough, it sounds like Gauss guns are an entirely different separate thing from both: https://en.wikipedia.org/wiki/Gauss_gun

Re: Are Gauss Guns railguns OR coilguns?
 

Most likely coilguns - those are the ones most frequently called Gauss guns in fiction. Railguns are probably going to ultimately not really work, due to the prodigious amounts of friction and subsequent waste heat involved in accelerating them, while I believe coilguns can actually be designed to have the projectile "float" in the barrel, avoiding most of the friction (there will still be some from air resistance, although that also goes away if using it in a vacuum).

Re: Are Gauss Guns railguns OR coilguns?
 

Lemme guess, the Gauss “gun” I linked to would not be able to be weaponized, as it also requires surface contact via the nonmagnetic track?

Re: Are Gauss Guns railguns OR coilguns?
 

Oh, railguns can be weaponized, but they'd lose a lot of energy to friction and burn through barrels very quickly. To my understanding, coilguns are superior in most ways, although I think they require much more precision (the coils need to turn on and off at just the right time for optimal acceleration, and a "floating" projectile would also call for high-precision machining, as any imperfection may result in it deviating and coming into contact with the inner wall). But an actual Gauss gun would probably be rather impractical. Note it's largely a passive system - while a coilgun or railgun burns through electricity to accelerate the projectile, a true Gauss gun uses fixed, permanent magnets. Considering it also involves an impact inside the barrel (the trigger ball strikes the magnet and the momentum is transferred to the projectile), that's also going to limit the destructive power (a sufficiently-strong trigger impact will destroy the magnet).

Re: Are Gauss Guns railguns OR coilguns?
 

Is the Gauss gun I linked to a railgun? I would’ve thought it’s a third entirely different thing. A Newton’s Cradle gun if you will.

Re: Are Gauss Guns railguns OR coilguns?
 

Sorry, your comment made me think you had interpreted what I said about railguns meaning they couldn't be weaponized and so neither could a true Gauss gun, on account of both basically traveling on rails. A railgun can be weaponized. For a true Gauss gun, I guess that would depend on what you count as a "weapon." I'd imagine you could design one that at least matched the performance of a sling, maybe even a pistol, but I don't think you'll be able to match a rifle. I'd expect such weapons to be fairly cumbersome, however.

Re: Are Gauss Guns railguns OR coilguns?
 

I see two problems with weaponizing this purported true Gauss gun.

- It's more or less a magnetic crossbow, storing energy by drawing back the trigger weight. That promises to make it really hard to store a lot of energy.

- Since the energy is passed to the shot by collision of solids you really need the forces in play to stay low enough that the parts only deform elastically during firing, limiting how fast the shot can be thrown. (Probably? You could make a version where the parts are disposable but you'd also be losing energy in the deformation so I question if it would be useful.)

Re: Are Gauss Guns railguns OR coilguns?
 

Immensely more. You need high speed switches and perfect precision, because the position of the projectile in the magnetic field is dynamically unstable, whereas a railgun just requires two rails with a large voltage difference and a magnetic field. GURPS doesn't really talk about the difference between different types of electromagnetic launcher and 'gauss gun' usually refers to coilguns, but I wouldn't be surprised if most of the low speed options (such as the EMGL) are railguns.

Re: Are Gauss Guns railguns OR coilguns?
 

Yeah, I figured that the “Gauss gun” is simply a name, the sci-fi parlance for coil guns just happen to coincide with it. Was just curious though since that doohickey was dubbed first.

Apparently there are two other potential weapons- a helical rail/coil hybrid gun and using EM effects to supercharge propellant:

https://youtu.be/Xll9rIzZPeQ

Re: Are Gauss Guns railguns OR coilguns?
 

The latter is what GURPS calls electrothermal or electrothermal-chemical.

Re: Are Gauss Guns railguns OR coilguns?
 

That's not the impression that I've got from reading Ultra Tech.

Re: Are Gauss Guns railguns OR coilguns?
 

Regarding the difficulties of creating a working coilgun- what happens when the magnetic coils fail to switch at the right time as the round is traveling through it?

Re: Are Gauss Guns railguns OR coilguns?
 

From my understanding, the coils serve to attract the projectile and pull it forward. Turning off too early means the projectile isn't pulled forward for as long, while failure to turn off at the right time will mean that the projectile starts to decelerate (due to the coils now pulling it backward). In both cases, that's going to slow down the projectile. Turning on too early in and of itself I think would just waste energy - but as many coilgun designs are reliant on capacitors that need charging, this will likely result in the coil turning off early due to the capacitor being emptied too soon. Due to the way these need to be designed, any issue here tends to compound on itself with later coils - if the first coil turns off too early or too late, the projectile is slowed down, and thus isn't in the right position (or going the right speed) when the next coil turns on, resulting in it functionally turning off too early, then this happens to the next one, then the next, etc - with enough coils, you might wind up with the projectile coming to stop or even being propelled backward a bit.

That assumes you have the coils working off timers. It might be possible to have something set up that detects the location of the projectile, turning the coil on when it reaches a certain point in the barrel and off when it reaches another (basically right in the middle of the coil if I'm understanding things correctly). Provided you design the capacitors to hold a larger charge than they need for typical operation, that would probably be more forgiving of early errors (you'd still wind up with a slower projectile at the end, but not to the same extent). I don't know how difficult it would be to design such (or if you even could), nor how much extra weight and power requirements you'd be adding on, but it might be an option.

However, I assume that with either version, having the projectile "float" rather than being in contact with the barrel would call for absolutely exacting precision, as any wobble will result in it veering off and coming into contact with the barrel wall. Something that uses the magnetic coils to push rather than pull it would probably be more conducive to having a "floating" projectile. I think that calls for the projectile to itself be a magnet (permanent or electromagnet), while the "pull" variant just needs it to be ferromagnetic.

Re: Are Gauss Guns railguns OR coilguns?
 

By itself, one coil (out of many) not working correctly is probably tolerable, but there's a risk it throws the stability of the whole system off, with results up to and including the projectile impacting the side of the barrel and the whole system needing to undergo major repairs.

Re: Are Gauss Guns railguns OR coilguns?
 

Working coilguns exist (Forgotten Weapons video), although they're very low-powered.

Re: Are Gauss Guns railguns OR coilguns?
 

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Re: Are Gauss Guns railguns OR coilguns?
 

The weapon in the video in question is an electromagnetic rocket gun, a railgun with a projectile containing coolant/propellant. Heat from the railgun evaporates the propellant, which is ionized into a plasma. In contrast, an electrothermal-chemical gun uses a pulse of plasma to combust conventional propellant. They have some similar operating principles, but they're not the same thing, and GURPS is not referring to EM rocket guns when it talks about ETC.

Note also that pure electrothermal guns (as in, not electrothermal-chemical guns) are also a separate thing, which uses a plasma pulse and an inert propellant like plastic flakes or water rather than gunpowder.