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Post by omnipotentvoid on Mar 2, 2017 15:34:45 GMT
The way capacitors work seems incredibly obscure.
For a start, why does changing the voltage have so little an effect on the performance of coil/railguns? From what I can see there must be some regulatory system behind them, because normally, even slight changes to the voltage have large effects on a railgun (I can say for sure) and probably a coilgun as well.
Beyond that, what kind of caps are these? I assume they're ceramic caps from the ceramics included? Without knowing how the capacitors work, designing one in game is just sliding a bunch of sliders around arbitrarily
Then, either the caps breaking from overheating throws the "Barrel shatters from thermal expansion" warning, or capacitors can put out a physics breaking amount of energy. Capacistiors obviously overheat, the game even tells you that you should check if the radiators are extended if they do, yet there are (as far as I can tell) no radiators for capacitors. Further more, coilguns don't seem to benefit much from additional stages, despite the average acceleration being the same when adding stages and thus increasing the acceleration time. This is exaggerated by the fact that each stage of the coilgun being fired in exactly the same way, despite the fact that the armature spends less time in each stage as it accelerates.
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Post by Enderminion on Mar 2, 2017 17:04:45 GMT
the reason why upping the power input on a capacitor weapon has no affect on muzzle velocity is because that is how much power you are feeding the capacitor, bigger capacitor = faster shots. also voltage is how much force the electricity is pumped with
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Post by omnipotentvoid on Mar 2, 2017 17:21:08 GMT
the reason why upping the power input on a capacitor weapon has no affect on muzzle velocity is because that is how much power you are feeding the capacitor, bigger capacitor = faster shots. also voltage is how much force the electricity is pumped with I'm not talking about upping power input. I'm talking about adding capacitors and barely getting any increase in velocity. As far as I can tell, adding a stage, and thus a capacitor, to a coilgun reduces the average acceleration across the entire coil by about 1/3. There is no reason for this as far as I can tell. Adding stages does have diminishing returns, as the armature spends less time in each coil, but if each coil has its own capacitor there is no reason for over all acceleration to decrease. |
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Post by Enderminion on Mar 2, 2017 17:24:47 GMT
coilguns don't work well with capacitors, you are limited to 20 stages and 20 capacitors
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Post by lieste on Mar 2, 2017 18:16:46 GMT
No you are not. Though there is little benefit seen with large numbers of stages. You can have up to 100, pointless as that is.
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Post by omnipotentvoid on Mar 2, 2017 18:50:33 GMT
No you are not. Though there is little benefit seen with large numbers of stages. You can have up to 100, pointless as that is. But why is it pointless? There is no reason for acceleration to decrease across the board when adding new stages the way it does. Each capacitor-coil pair should fire independently, acting like an individual gun. Velocity gain would decrease as the projectile is already moving faster when it enters and some acceleration is lost due to increased resistance due to increased wire length (this is negligible unless the gun is very long), but acceleration should not drop as much. |
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Post by Enderminion on Mar 2, 2017 19:22:19 GMT
I have stopped using coils but I have heard of CTDs regrading stage and capacitors greater then 20
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Post by omnipotentvoid on Mar 2, 2017 20:37:18 GMT
First of all: capacitors don't heat up, it's the barrels that heat up. This is confirmed by the fact that increasing barrel radius/armour on a railgun decreases heat jump temperature. This means capacitors are likely more broken than coilguns were before. See image below:  Basically, a capacitor with a total electric energy of 111mJ is heating 217 tons of zirconium copper by 2108K. With a heat capacity of 385 J/Kg K, that should take about 176GJ, making that little cap roughly 160000000000000% efficient at heating up the railgun. It takes over 300t (at least) of zirconium copper before the railgun does not heat up at all. Secondly: here's a graph I made to show how coilguns don't accelerate as they should:  In the constant acceleration curve, the acceleration the armature experiences is the same in each coil (50000 m/s^2 with 1 m long stages in this case). In the decreasing acceleration curve the first stage is identical to the first constant acceleration stage, each stage following that loses 1/3*Pa*exp(-(Stg-2)) in acceleration, where Pa the acceleration of the previous stage and Stg is the stage number. This way the second stage loses about 1/3 of its acceleration and following stages lose less and less. This is only a rough approximation, because in game adding a stage decreases the acceleration of all stages, but it roughly shows the effect that decreasing acceleration of individual stages has on velocity. To go back to my point: there is, as far as I'm aware, no reason why multiple stages should decrease the acceleration on an armature in a coilgun. If each capacitor/coil pair is on its own circuit, the magnetic field, and thus the acceleration should be the same. |
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Post by vegemeister on Mar 2, 2017 22:54:23 GMT
Yeah, both coilguns and railguns have some weird problem where changes to the muzzle end of the barrel can cause effects *upstream*.
Increasing the length of a railgun reduces the stress on the projectile, which is nonsensical because only the part of the barrel between the breech and the projectile participates in the circuit. You should be *able* to reduce the stress on the projectile by making the barrel longer, but it doesn't make sense for it to just happen.
Coilguns have a similar effect, where if you optimize a single stage, adding stages reduces the acceleration of the first, so that the overall benefit is negligible. However, if you start with multiple stages and optimize that, removing stages from the end makes the whole thing violate stress limits. That makes no sense. It should reduce the muzzle velocity.
Also the "capacitor count" option for railguns is very strange. It doesn't connect caps in parallel, or in series as it claims. It *switches the caps out as the projectile is moving down the barrel*. I'm skeptical that this is physically possible with the currents involved.
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Post by underwhelmed on Mar 3, 2017 4:00:05 GMT
Even stranger, the rest of the charge of the first capacitor just remains undischarged... but recharge rate still treats it as fully depleted.
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Post by n2maniac on Mar 7, 2017 7:45:43 GMT
First of all: capacitors don't heat up, it's the barrels that heat up. This is confirmed by the fact that increasing barrel radius/armour on a railgun decreases heat jump temperature. This means capacitors are likely more broken than coilguns were before. See image below: Basically, a capacitor with a total electric energy of 111mJ is heating 217 tons of zirconium copper by 2108K. With a heat capacity of 385 J/Kg K, that should take about 176GJ, making that little cap roughly 160000000000000% efficient at heating up the railgun. It takes over 300t (at least) of zirconium copper before the railgun does not heat up at all. Secondly: here's a graph I made to show how coilguns don't accelerate as they should: In the constant acceleration curve, the acceleration the armature experiences is the same in each coil (50000 m/s^2 with 1 m long stages in this case). In the decreasing acceleration curve the first stage is identical to the first constant acceleration stage, each stage following that loses 1/3*Pa*exp(-(Stg-2)) in acceleration, where Pa the acceleration of the previous stage and Stg is the stage number. This way the second stage loses about 1/3 of its acceleration and following stages lose less and less. This is only a rough approximation, because in game adding a stage decreases the acceleration of all stages, but it roughly shows the effect that decreasing acceleration of individual stages has on velocity. To go back to my point: there is, as far as I'm aware, no reason why multiple stages should decrease the acceleration on an armature in a coilgun. If each capacitor/coil pair is on its own circuit, the magnetic field, and thus the acceleration should be the same. Going to take a guess and say the barrel (which is 1cm thick) is heated by 2000K while the barrel armor is not. If the whole barrel heats up in usage on the first shot, then you found a bug. |
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Post by midnightdreary on Mar 7, 2017 20:39:43 GMT
I'm still in the very early stages of finding the sweet spot for everything, but I don't really see the problem with capacitors. Their size seems to be very important though. I only run in to problem in very large systems.  |
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Post by omnipotentvoid on Mar 9, 2017 19:15:24 GMT
First of all: capacitors don't heat up, it's the barrels that heat up. This is confirmed by the fact that increasing barrel radius/armour on a railgun decreases heat jump temperature. This means capacitors are likely more broken than coilguns were before. See image below: Basically, a capacitor with a total electric energy of 111mJ is heating 217 tons of zirconium copper by 2108K. With a heat capacity of 385 J/Kg K, that should take about 176GJ, making that little cap roughly 160000000000000% efficient at heating up the railgun. It takes over 300t (at least) of zirconium copper before the railgun does not heat up at all. Secondly: here's a graph I made to show how coilguns don't accelerate as they should: In the constant acceleration curve, the acceleration the armature experiences is the same in each coil (50000 m/s^2 with 1 m long stages in this case). In the decreasing acceleration curve the first stage is identical to the first constant acceleration stage, each stage following that loses 1/3*Pa*exp(-(Stg-2)) in acceleration, where Pa the acceleration of the previous stage and Stg is the stage number. This way the second stage loses about 1/3 of its acceleration and following stages lose less and less. This is only a rough approximation, because in game adding a stage decreases the acceleration of all stages, but it roughly shows the effect that decreasing acceleration of individual stages has on velocity. To go back to my point: there is, as far as I'm aware, no reason why multiple stages should decrease the acceleration on an armature in a coilgun. If each capacitor/coil pair is on its own circuit, the magnetic field, and thus the acceleration should be the same. Going to take a guess and say the barrel (which is 1cm thick) is heated by 2000K while the barrel armor is not. If the whole barrel heats up in usage on the first shot, then you found a bug. Even without armour, the 111mJ cap can heat a little more than a ton of ZrCu to about 1500K. Thats still way more energy gain than was possible with the old coilguns. |
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Post by n2maniac on Mar 10, 2017 7:14:53 GMT
Going to take a guess and say the barrel (which is 1cm thick) is heated by 2000K while the barrel armor is not. If the whole barrel heats up in usage on the first shot, then you found a bug. Even without armour, the 111mJ cap can heat a little more than a ton of ZrCu to about 1500K. Thats still way more energy gain than was possible with the old coilguns. You are correct (though the screenshot and some math would suggest about 141kg of copper, but still much more than should be affected by 0.1J). Hmm, perhaps the game is modeling it in parallel with the power input (as a constant power source)? If that is correct lets see: 50m * 2 / 1.28m/s ~= 80s to exit the barrel, correct? 80s * 100W = 8kJ of heat in 141kg of copper -> 0.15 K rise, no, that isn't right either. Yea, you definitely found something weird. |
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Post by omnipotentvoid on Mar 10, 2017 9:56:47 GMT
Even without armour, the 111mJ cap can heat a little more than a ton of ZrCu to about 1500K. Thats still way more energy gain than was possible with the old coilguns. You are correct (though the screenshot and some math would suggest about 141kg of copper, but still much more than should be affected by 0.1J). Hmm, perhaps the game is modeling it in parallel with the power input (as a constant power source)? If that is correct lets see: 50m * 2 / 1.28m/s ~= 80s to exit the barrel, correct? 80s * 100W = 8kJ of heat in 141kg of copper -> 0.15 K rise, no, that isn't right either. Yea, you definitely found something weird. It seems to have something to do with capacitor dimensions. Some width/height ratios can produce <100% efficient coilguns as well, heating them to about -16000K. |
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