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Post by jtyotjotjipaefvj on Jun 8, 2018 14:10:10 GMT
I noticed multistage capacitor coilguns seem to work under the same assumption as coilguns with no capacitor. Adding a second identical stage (including a second capacitor) to a coilgun should not affect the first stage in any way. It does, however, almost halve the acceleration across both stages which makes no sense to me. It also seems that multistage coilgun efficiency is limited to 1 / number of stages as a result of this. Without a capacitor, I have no problems getting a 100-stage coilgun past 80% efficiency, but with a capacitor even a two-stage gun is impossible to get much higher than 40%. It seems to me there's a bug in the capacitor logic where only one capacitor is actually used to drive the coil, but additional capacitors are created and charged despite them being left unused. This, combined with the 50-turn limit on single stages, is likely what is making coilguns perform so poorly in the game, compared to railguns at least. Below are some screenshots showing a one- and two-stage version of the same coilgun, showing the drop in both peak acceleration and efficiency. You'd expect a coilgun this slow to just get a higher muzzle velocity with a second stage, but that's not the case here due to what I'm assuming must be a bug. One-stage version:  Two-stage version.  |
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Post by AtomHeartDragon on Jun 9, 2018 4:50:29 GMT
That's a great find - it's clear that it's a bug because no matter what happens at second stage it shouldn't affect the first which has its own capacitor - yet it does.
If this gets fixed the mighty 34mm heavy coilgun might finally leave the garbage tier - of course after it gets tweaked so that 3x the energy it was built to handle originally doesn't melt or burst the coils.
As of now - we now know to use single stage or feed directly from the reactor.
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Post by jtyotjotjipaefvj on Jun 11, 2018 20:36:09 GMT
There seems to be something questionable going on with railguns as well. Based on fairly comprehensive testing, I can make a railgun with no capacitors or just one capacitor that exceeds 50% efficiency, which seems like a fairly arbitrary limit. Additionally, railguns with multiple capacitors seem to be limited to 50% / number of capacitors efficiency. Perhaps it's time to have a look at both coilguns and railguns and see if there's some underlying issue with the way they work.
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Post by AtomHeartDragon on Jun 12, 2018 19:53:24 GMT
It is likely to also be the case with railguns, however in coilguns it's easier to test for and verify - multistage coilguns are pretty much completely separate additional coilguns on top of a single stage one. Multistage railgun is single pair of rails with extra capacitors kicking in sequentially.
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Post by lieste on Jun 13, 2018 17:14:52 GMT
There seems to be something questionable going on with railguns as well. Based on fairly comprehensive testing, I can make a railgun with no capacitors or just one capacitor that exceeds 50% efficiency, which seems like a fairly arbitrary limit. Additionally, railguns with multiple capacitors seem to be limited to 50% / number of capacitors efficiency. Perhaps it's time to have a look at both coilguns and railguns and see if there's some underlying issue with the way they work. 50% efficiency is the theoretical limit for stored/recovered electrical power in capacitors. The difference between a railgun with capacitor and without is the size of the power generation needed to operate the weapon at all. A small weapon is more efficient with direct application of power. |
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Post by jtyotjotjipaefvj on Jun 13, 2018 17:47:31 GMT
There seems to be something questionable going on with railguns as well. Based on fairly comprehensive testing, I can make a railgun with no capacitors or just one capacitor that exceeds 50% efficiency, which seems like a fairly arbitrary limit. Additionally, railguns with multiple capacitors seem to be limited to 50% / number of capacitors efficiency. Perhaps it's time to have a look at both coilguns and railguns and see if there's some underlying issue with the way they work. 50% efficiency is the theoretical limit for stored/recovered electrical power in capacitors. The difference between a railgun with capacitor and without is the size of the power generation needed to operate the weapon at all. A small weapon is more efficient with direct application of power. That would make a lot of sense, except you can't get past 50% even without a capacitor on a railgun, and coilguns with single capacitors willl happily exceed 90%. |
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Post by AtomHeartDragon on Jun 13, 2018 18:15:09 GMT
I have just seen a >200% one in Workshop.
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Post by jtyotjotjipaefvj on Jul 3, 2018 17:55:43 GMT
The questionable capacitor efficiency when staging still happens in the latest version. I also noticed that coilgun firing time is not taken into account at all, which can lead to coilguns that have over 100% actual efficiency, despite what's claimed by the weapon info screen. If the firing time is longer than one simulation tick, you can use a loader that's faster to get free energy out of your coilgun. For example this gun fires 8.2 kJ rounds at 15 rounds per second, dictated by the loader speed, producing 125 kW of kinetic energy output while only draining 10 kW power.  Rate of fire should be limited by firing time as well, not just loader and capacitor. I haven't tested this for railguns but I assume same thing happens there as well. |
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Post by AtomHeartDragon on Jul 3, 2018 18:59:03 GMT
The questionable capacitor efficiency when staging still happens in the latest version. I also noticed that coilgun firing time is not taken into account at all, which can lead to coilguns that have over 100% actual efficiency, despite what's claimed by the weapon info screen. If the firing time is longer than one simulation tick, you can use a loader that's faster to get free energy out of your coilgun. For example this gun fires 8.2 kJ rounds at 15 rounds per second, dictated by the loader speed, producing 125 kW of kinetic energy output while only draining 10 kW power. Rate of fire should be limited by firing time as well, not just loader and capacitor. I haven't tested this for railguns but I assume same thing happens there as well. Confirmed, it's the case with railguns as well - have one that takes 2ms to fire, but reloads faster.
With coilguns you could at least argue that you could accelerate multiple sufficiently separated projectiles down the barrel simultaneously - though of course it would either need to consume more energy (and require bracing to cope with increased forces) or impart less force on the projectiles. With railgun you don't even have that excuse.
BTW: that could be another use case for multibarrel guns.
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Post by jtyotjotjipaefvj on Jul 3, 2018 19:26:54 GMT
]Confirmed, it's the case with railguns as well - have one that takes 2ms to fire, but reloads faster. You don't really get any benefit in that case. Guns operate at 30 Hz frequency, anything inbetween is skipped. Your gun will fire only 30 rounds per second despite the massive reload speed. |
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Post by tepidbread on Jul 4, 2018 3:01:36 GMT
Sorry if I am misunderstanding this I just got the game on sale recently. I tend to agree that capacitors are broken. I did not save the part but I got a coilgun with approximately 105% efficiency in the latest version of the game in the method stated above.
I have noticed that the total capacitance of the coil gun seems to remain the same regardless of the number of stages even though the number of capacitors scales with the number of stages. Moreover, It also seems that the heating generated is changed even though the total amount of energy and capacitance has not changed. In summery an X stage multistage coil gun pays for the materials of X capacitors and suffers from the heating of X capacitors whilst the capacitance remains the same. In effect single stage coil guns are objectively better but are severely handicapped in the projectiles that they can launch compared to rail guns.
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Post by antonindvorak on Jul 8, 2018 19:04:15 GMT
50% efficiency is the theoretical limit for stored/recovered electrical power in capacitors. The capacitor's energy is 1/2 C V2 J(oule), right? And when we charge a capacitor (with a constant voltage source), we waste the the same amount, right? So ... let us charge up a capacitor with a source that delivers 7 V more than the capacitor. Energy wasted: 1/2 C 72 JLet's repeat that. Energy wasted: 2* 1/2 C 72 JAnd again ... Energy wasted: 3* 1/2 C 72 J... for a total of 10 times: Energy wasted: 10* 1/2 C 72 JThe capacitor now has 10 * 7 Volt == 70 Volt (the breakdown voltage of the coilgun's capacitor here), and therefore the energy stored is ... 1/2 C 702 J. Wasted energy (total) = 5 * C * 49 J == 245 * C J
Stored energy (total) = 1/2 * C * 4.900 J == 2.450 * C JThat looks more like 91% efficiency to me. I think you will find that your theoretical efficiency is only true for a simple constant voltage charge, and does not hold with a multi-step constant voltage charge, nor a constant current or current limited charge nor a inductive coil in line with a V/2 source charge ... ... but of course, that means a slower charging process. |
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