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Post by jackvernian on Dec 7, 2018 19:54:57 GMT
Here you can see the problem: Note that it goes away if I use any other dielectric material rather than water. Here's the volume point at which it goes back to "normal": And here's the point at which it starts to diverge into negative values: |
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Post by tepidbread on Dec 8, 2018 8:22:34 GMT
Coil guns are bugged in general. That is not the only configuration that results in efficiencies above 100%. There are many aspects that are bugged with them. I personally experienced similar things when I used the minimum possible power for the loader. Additionally, capacitance is does not work correctly for multistage coil-guns. When you add an additional coil-gun stage another capacitor gets added in terms of mass and heat generation, however the total capacitance of all the stages does not change. As a result of this, multistage coil-guns have the mass and heat generation of multiple capacitors, yet have the capacitance of a single capacitor divided up among all the stages. |
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Post by bigbombr on Dec 8, 2018 9:36:45 GMT
Coil guns are bugged in general. That is not the only configuration that results in efficiencies above 100%. There are many aspects that are bugged with them. I personally experienced similar things when I used the minimum possible power for the loader. Additionally, capacitance is does not work correctly for multistage coil-guns. When you add an additional coil-gun stage another capacitor gets added in terms of mass and heat generation, however the total capacitance of all the stages does not change. As a result of this, multistage coil-guns have the mass and heat generation of multiple capacitors, yet have the capacitance of a single capacitor divided up among all the stages. Yes, and coilguns being bugged is a shame as they might actually be very viable weapons otherwise as I got the impression they offer increased performance, especially with heavier rounds when compared to railguns at the price of increased ammo cost. |
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Post by AtomHeartDragon on Dec 8, 2018 12:16:37 GMT
The main problem with coilguns is that their projectile acceleration curves are quite complicated, so their performance is greatly impacted by inaccuracies of numerical integration - at some points you will hit all the peaks when tweaking parameters and BAM! >200% efficiency.
At least multistage bug only affects capacitor coilguns and doesn't produce physics violating crap, so until it's fixed you can just avoid making multistage capacitor designs unless you cannot work around thermal/mechanical considerations in any other way.
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Post by jackvernian on Dec 8, 2018 13:58:07 GMT
Well, I thought it was obvious from the screenshot but this is a single-stage design.
Numerical Integration seems to be a fairly easy thing to fix. You can use simpson's curves, or flexible step methods for increased accuracy.
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Post by cipherpunks on Jan 29, 2019 0:31:55 GMT
Coil guns are bugged [...] another capacitor gets added in terms of mass and heat generation, however the total capacitance of all the stages does not change. As a result of this, multistage coil-guns have the mass and heat generation of multiple capacitors, yet have the capacitance of a single capacitor divided up among all the stages. I've just looked into similar thing, but on a railgun. Seems to me that multiple capacitors only work when you have thin, long rails (and it's not the best config). At least I can see sawtooth-like profile on that graph. But as you add thickness to rails and reduce their length, last sawtooth moves to the right, then off-graph, and then there's a point when 2nd capacitor adds nothing performance-wise (except weight penalty). Looks like multiple capacitor discharge time isn't scaled properly w.r.t. rail configuration?.. So it's not only coil guns that are bugged... Heck, we need a fix. |
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Post by tepidbread on Jan 29, 2019 2:55:37 GMT
Coil guns are bugged [...] another capacitor gets added in terms of mass and heat generation, however the total capacitance of all the stages does not change. As a result of this, multistage coil-guns have the mass and heat generation of multiple capacitors, yet have the capacitance of a single capacitor divided up among all the stages. I've just looked into similar thing, but on a railgun. Seems to me that multiple capacitors only work when you have thin, long rails (and it's not the best config). At least I can see sawtooth-like profile on that graph. But as you add thickness to rails and reduce their length, last sawtooth moves to the right, then off-graph, and then there's a point when 2nd capacitor adds nothing performance-wise (except weight penalty). Looks like multiple capacitor discharge time isn't scaled properly w.r.t. rail configuration?.. So it's not only coil guns that are bugged... Heck, we need a fix. Yeah. I noticed this since I last posted. A fix would definitely be appreciated, however I have not seen qswitched on here in over 6 months. |
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