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Post by RiftandRend on Jul 12, 2017 0:50:54 GMT
A potential solution to heating issues, would a very short super high acceleration railgun work? If both the barrel and projectile are made of atomicly perfect nanomaterials there should not be destructive levels of friction. Also, is there any practical value in firing liquid projectiles?
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Post by AdmiralObvious on Jul 12, 2017 6:32:57 GMT
A potential solution to heating issues, would a very short super high acceleration railgun work? If both the barrel and projectile are made of atomicly perfect nanomaterials there should not be destructive levels of friction. Also, is there any practical value in firing liquid projectiles? As far as I know, firing a liquid is going to be pretty useless since whatever you are firing is already closer to becoming plama than something relatively cold. Assuming it penetrated a whipple shield, it will probably spread out more as plasma. Also, it'll probably just be less likely to do any damage, since hot things like to pull apart, and not stick together, especially molten metals.
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Post by coaxjack on Jul 12, 2017 15:45:09 GMT
Since metals typically lose their magnetic properties when heated, it's dubious if the projectile would even leave the barrel once liquified.
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Post by alias72 on Jul 12, 2017 16:09:22 GMT
so... does that mean that our rail-guns won't work?
I bring this up because if hyper-velocity micro-projectiles aren't practical than Whipple shields are significantly less important.
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Post by AdmiralObvious on Jul 12, 2017 18:53:24 GMT
so... does that mean that our rail-guns won't work? I bring this up because if hyper-velocity micro-projectiles aren't practical than Whipple shields are significantly less important. If you can measure it with the naked eye, it's probably going to be fine. If what your'e shooting is smaller than most dust particles, then you might have a problem.
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Post by omnipotentvoid on Jul 12, 2017 19:08:16 GMT
so... does that mean that our rail-guns won't work? I bring this up because if hyper-velocity micro-projectiles aren't practical than Whipple shields are significantly less important. They're paracticality is a complex problem. With supercunducting rails and molecular perfect engeniering they may very well be possible, or they may not be. Wipple shields are still pretty useless against hyper velocity projectiles, since the time it takes the projectiles plasma to cross the gap in armor is in the range of a few microseconds at most, meaning the plasma will still have a cross sectional density comparable to that of the original projectile when it hits the main armor layer. To be as effective as they are against standard velocity railguns (at around a few hundred km/s at most) wipple shields need to be at least tens of meters away from the main armor, making them disproportionatly heavy.
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Post by RiftandRend on Jul 12, 2017 21:16:25 GMT
Since metals typically lose their magnetic properties when heated, it's dubious if the projectile would even leave the barrel once liquified. Aren't magnetic properties irrelevent to railguns? As far as I know conductivity is all that matters.
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Post by omnipotentvoid on Jul 12, 2017 21:56:38 GMT
Since metals typically lose their magnetic properties when heated, it's dubious if the projectile would even leave the barrel once liquified. Aren't magnetic properties irrelevent to railguns? As far as I know conductivity is all that matters. Yes, the magnetic field is generated by the current flowing through the circuit, thus the state of matter of the rails and projectile don't matter to the magnetic field. In fact, the only property that is required of the armature is electrical conductivity and since all materials are conductive given high enough voltage, anything can be used as an armature.
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Post by bigbombr on Jul 12, 2017 22:04:40 GMT
Aren't magnetic properties irrelevent to railguns? As far as I know conductivity is all that matters. Yes, the magnetic field is generated by the current flowing through the circuit, thus the state of matter of the rails and projectile don't matter to the magnetic field. In fact, the only property that is required of the armature is electrical conductivity and since all materials are conductive given high enough voltage, anything can be used as an armature. An increase in temperature tends to increase electrical resistance, causing more loss, heating up the projectile more. You'd be limited to projectiles that don't exhibit this behaviour.
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Post by coaxjack on Jul 12, 2017 22:31:30 GMT
Right, right, my bad. It's Lorentz force not the actual magnetism of the armature. Still, I think the point still stands that if you apply enough electricity to accelerate a 50 mg flake of metal to hundreds of km/s, it's going to melt. Maybe if you chilled it to superconducting temperature, otherwise anything above 0.00000000... ohms will heat it to vapor right quick.
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Post by dorkious on Jul 15, 2017 16:49:28 GMT
Right, right, my bad. It's Lorentz force not the actual magnetism of the armature. Still, I think the point still stands that if you apply enough electricity to accelerate a 50 mg flake of metal to hundreds of km/s, it's going to melt. Maybe if you chilled it to superconducting temperature, otherwise anything above 0.00000000... ohms will heat it to vapor right quick. Superconductors have a magnetic field limit, if the field goes over this limit it stops super conducting. I suspect the magnetic field magnitude in a hypervelocity gun would be over this limit. I don't think the current railguns are physically possible. However dust accelerators can get velocities of 100kmps for 0.2 micron dust ( Colorado lunar dust facility CCLDAS).
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Post by Enderminion on Jul 15, 2017 18:02:43 GMT
Right, right, my bad. It's Lorentz force not the actual magnetism of the armature. Still, I think the point still stands that if you apply enough electricity to accelerate a 50 mg flake of metal to hundreds of km/s, it's going to melt. Maybe if you chilled it to superconducting temperature, otherwise anything above 0.00000000... ohms will heat it to vapor right quick. Superconductors have a magnetic field limit, if the field goes over this limit it stops super conducting. I suspect the magnetic field magnitude in a hypervelocity gun would be over this limit. I don't think the current railguns are physically possible. However dust accelerators can get velocities of 100kmps for 0.2 micron dust ( Colorado lunar dust facility CCLDAS). how does magnetism play into electric conductivity?
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Post by dorkious on Jul 16, 2017 8:21:35 GMT
Superconductors have a magnetic field limit, if the field goes over this limit it stops super conducting. I suspect the magnetic field magnitude in a hypervelocity gun would be over this limit. I don't think the current railguns are physically possible. However dust accelerators can get velocities of 100kmps for 0.2 micron dust ( Colorado lunar dust facility CCLDAS). how does magnetism play into electric conductivity? Superconductors have a critical field, if the magnetic field goes over this value it stops super conducting. Well to be more specific there are two broad categories type one and type two. Type one has a hard transition with a single critical field values, type two a spread out transition. For one are normally a single element, type two are often compounds. There can also be a different critical field in different directions. The Wikipedia page is quite good, covers all the important points. Cuprates, (type 2) can have critical field up to 100 Tesla according to Wikipedia.
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