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Post by Enderminion on Sept 1, 2017 19:14:45 GMT
although with the power plant needed you could mount a fairly hefty laser, also masses as much as a tank I wonder how much an tank has to weight to carry this railgun. 200t? 300-400 seems about right, bigger if you want more armour, on the other hand a laser with this power input has a TW range of 2250m while fitting into the turret of a M1A2 and only massing 400kg (mostly armour)
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Post by RiftandRend on Sept 1, 2017 19:17:46 GMT
I wonder how much an tank has to weight to carry this railgun. 200t? 300-400 seems about right, bigger if you want more armour, on the other hand a laser with this power input has a TW range of 2250m while fitting into the turret of a M1A2 and only massing 400kg (mostly armour) I wonder if that laser would ignite the atmosphere along it's beam...
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Post by Kerr on Sept 1, 2017 19:18:44 GMT
I wonder how much an tank has to weight to carry this railgun. 200t? 300-400 seems about right, bigger if you want more armour, on the other hand a laser with this power input has a TW range of 2250m while fitting into the turret of a M1A2 and only massing 400kg (mostly armour) And frequency? Also laser blooming
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Post by Kerr on Sept 1, 2017 19:20:37 GMT
300-400 seems about right, bigger if you want more armour, on the other hand a laser with this power input has a TW range of 2250m while fitting into the turret of a M1A2 and only massing 400kg (mostly armour) I wonder if that laser would ignite the atmosphere along it's beam... "ignite" ? Turning into plasma, yes. Fusion, no. Maybe with PW intensities.
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Post by Enderminion on Sept 1, 2017 19:23:41 GMT
300-400 seems about right, bigger if you want more armour, on the other hand a laser with this power input has a TW range of 2250m while fitting into the turret of a M1A2 and only massing 400kg (mostly armour) And frequency? Also laser blooming 347nm (once doubled ruby) with a 30cm radius mirrior, 5.07Tw at one Km
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Post by themohawkninja on Sept 1, 2017 23:31:12 GMT
Hello, I recently watched a video talking about how railguns are potentially not the best solution for modern militaries given that conventional artillery can provide the same destructive power on ground targets, and solid state lasers work great for shooting down missiles. It also pointed out that if it is possible, we are probably somewhat far off from the power requirements being small enough to allow for mounting on a tank or other such system. It got me thinking though, would it be feasible to have a self-contained expendable railgun cartridge comprised of the projectile and a supercapacitor holding the required charge? If it could be made small enough, that would allow for anti-tank sized weaponry, which would be a great way to exploit the extremely high penetration that a railgun offers. I just don't know enough about the math behind it to start looking into it. There's a force equation on the Wikipedia page that uses amperage, armature length, and field strength, but I don't really know enough about electricity to have a clue how to tackle the issue, if the answer is even within the ballpark of current technology. Current supercapacitors have energy densities of 10kj/kg. We need an 30 times increase to allow an 10kg supercapacitor to produce enough power to accelerate an 1kg projectile to Mach 7 or 2.4km/s. An Flywheel could, if made out of high GPa materials have energy densities superior to high explosives. That might allow this. This assumes 100% efficent railguns. The navy railgun is supposed to have 33%. 30x the energy to get it to 2400 m/s? So, presumably that currently puts us at a 10kg supercapacitor accelerating a 1kg projectile to 80 m/s assuming 100% efficiency? Well, that puts us at m203 grenade launcher velocities, but those 40mm grenades aren't exactly 11kg. Is there a theoretical energy density limit that could prevent my idea from working, or is it just a matter of material science advancing enough to make it possible? Assuming there aren't other issues making it impossible, or at least not good enough compared to other solutions to be viable.
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Post by Kerr on Sept 1, 2017 23:49:21 GMT
Current supercapacitors have energy densities of 10kj/kg. We need an 30 times increase to allow an 10kg supercapacitor to produce enough power to accelerate an 1kg projectile to Mach 7 or 2.4km/s. An Flywheel could, if made out of high GPa materials have energy densities superior to high explosives. That might allow this. This assumes 100% efficent railguns. The navy railgun is supposed to have 33%. 30x the energy to get it to 2400 m/s? So, presumably that currently puts us at a 10kg supercapacitor accelerating a 1kg projectile to 80 m/s assuming 100% efficiency? Well, that puts us at m203 grenade launcher velocities, but those 40mm grenades aren't exactly 11kg. Is there a theoretical energy density limit that could prevent my idea from working, or is it just a matter of material science advancing enough to make it possible? Assuming there aren't other issues making it impossible, or at least not good enough compared to other solutions to be viable. Graphene supercapacitors are supposed to have 50Wh/kg or 0.18MJ/kg. Some predict that we will reach 350Wh/kg in the next decade or so. 1.25MJ/kg. An 16kg device could then store 20MJ. And accelerate an 4.8kg rod with a 33% railgun to 1625m/s. In the near future a capacitor railgun would have no advantage over an chemical gun.
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Post by Enderminion on Sept 2, 2017 0:33:42 GMT
30x the energy to get it to 2400 m/s? So, presumably that currently puts us at a 10kg supercapacitor accelerating a 1kg projectile to 80 m/s assuming 100% efficiency? Well, that puts us at m203 grenade launcher velocities, but those 40mm grenades aren't exactly 11kg. Is there a theoretical energy density limit that could prevent my idea from working, or is it just a matter of material science advancing enough to make it possible? Assuming there aren't other issues making it impossible, or at least not good enough compared to other solutions to be viable. Graphene supercapacitors are supposed to have 50Wh/kg or 0.18MJ/kg. Some predict that we will reach 350Wh/kg in the next decade or so. 1.25MJ/kg. An 16kg device could then store 20MJ. And accelerate an 4.8kg rod with a 33% railgun to 1625m/s. In the near future a capacitor railgun would have no advantage over an chemical gun. ah but chemical weapons struggle to get above ~3km/s, a railgun can hit 4-7km/s easy
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Post by Kerr on Sept 2, 2017 0:45:04 GMT
Graphene supercapacitors are supposed to have 50Wh/kg or 0.18MJ/kg. Some predict that we will reach 350Wh/kg in the next decade or so. 1.25MJ/kg. An 16kg device could then store 20MJ. And accelerate an 4.8kg rod with a 33% railgun to 1625m/s. In the near future a capacitor railgun would have no advantage over an chemical gun. ah but chemical weapons struggle to get above ~3km/s, a railgun can hit 4-7km/s easy To hit 3km/s you need an 64kg supercapacitor and for 6km/s. For which you could carry 3-12 extra chem-rounds. Also, 6km/s is the maximum velocity for in atmosphere use.
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Post by themohawkninja on Sept 2, 2017 0:49:19 GMT
ah but chemical weapons struggle to get above ~3km/s, a railgun can hit 4-7km/s easy To hit 3km/s you need an 64kg supercapacitor and for 6km/s. For which you could carry 3-12 extra chem-rounds. Also, 6km/s is the maximum velocity for in atmosphere use. Why the velocity limit? Do you start getting into issues with round ablation due to ram/friction?
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Post by Kerr on Sept 2, 2017 0:55:30 GMT
To hit 3km/s you need an 64kg supercapacitor and for 6km/s. For which you could carry 3-12 extra chem-rounds. Also, 6km/s is the maximum velocity for in atmosphere use. Why the velocity limit? Do you start getting into issues with round ablation due to ram/friction? Air molecules just slam into the projectile. Heating it up and slowing it rapidly down. Also barrel erosion is extreme at these velocities.
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Post by bigbombr on Sept 2, 2017 7:01:05 GMT
If you want high muzzle velocities, you can also use a RAM accelerator. Unlike a railgun, it doesn't require electrical power, but it reaches similar velocities.
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Post by treptoplax on Sept 2, 2017 12:55:59 GMT
The fundamental issue with the original proposal is that capacitor energy density is limited by material strength, which relates to energy in chemical bonds... So order-of-magnitude it'll be similar to chemical energy storage, likely worse. Same with flywheels, though I might believe those coming out a few percentage points better.
No non-nuclear power source is going to beat explosives by a dramatic margin.
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Post by bigbombr on Sept 2, 2017 13:10:55 GMT
The fundamental issue with the original proposal is that capacitor energy density is limited by material strength, which relates to energy in chemical bonds... So order-of-magnitude it'll be similar to chemical energy storage, likely worse. Same with flywheels, though I might believe those coming out a few percentage points better. No non-nuclear power source is going to beat explosives by a dramatic margin. Graphene or carbon nanotube flywheels might, but I roughly agree. Metallic hydrogen propellant is a decent competitor too though, and is only surpassed by nucleair reactors and antimatter for energy density.
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Post by Kerr on Sept 2, 2017 13:13:39 GMT
The fundamental issue with the original proposal is that capacitor energy density is limited by material strength, which relates to energy in chemical bonds... So order-of-magnitude it'll be similar to chemical energy storage, likely worse. Same with flywheels, though I might believe those coming out a few percentage points better. No non-nuclear power source is going to beat explosives by a dramatic margin. The limits on a flywheel is the yield strenght of the disk. An perfect 100GPa CNT flywheel could reach 200MJ/kg. 175x that of JA-2. But no matter what you do. The advantages wouldn't don't outweight the drawbacks and the cost.
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