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Post by concretedonkey on Mar 17, 2017 20:34:23 GMT
A few weeks ago uberdude9001 asked for accuracy info in the guns designer and during the conversation I did a few tests but wasn't very satisfied - maybe it was the post needle-gun depression, I don't know anyway I decided to do some additional tests somewhere in the future when I'm bored by the redesign thread and here we are... First lets start from the railgun I used in the tests in the uberdude's thread: As you can see my desperate quest for more speed led me to a stupidly long gun with a barrel material that I understood was broken around the time of the conversation. At 1000 kilometers grouping is wide across the target. Target is a 100 meter wide osmium slab btw. I returned to the tests with a small rework of one of my main guns 50 t turret firing 1g slug at 20km/s .I shortened the barrel, widened the armor bracing to the maximum and twiddled with the numbers untill I got to a similar performance to its longer more conventional cousin. Gun and grouping at 1000km looks like this: As you can see we already have a tendency - shorter and more armored, barrel gives us much better results (less flexible I guess). Next I decided to go to more dense materials and turned to an old friend - beryllium copper. Again shortened the barrel. Gun and results at 1000km look like this: Slightly better but is it worth almost twice the weight of the turret? I don't know... lets escalate... osmium barrel. This is were it gets interesting... 182 tons of turret for just 1.9 meters of barrel length. Almost no dispersal. I mean look at it. From time to time a rogue particle was making it a bit less... laser-like but generally it was unnatural. Needless to say it will significantly affect my gun designs. I sure hope its not another bug or exploit, I hope its just the super massive incredibly short and inflexible barrel, but sure the results look too good to be true.
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Post by Durandal on Mar 17, 2017 20:42:22 GMT
I hope those aren't broken, because that osmium gun looks like a very nice little compact low-power packages. What was their cost? Last bit was cut off on your images.
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Post by concretedonkey on Mar 17, 2017 20:46:09 GMT
5.45 million. It is expensive and very heavy, I'll probably look for some kind of ballance between the beryllium copper and the osmium one. Probably vanadium steel? I'm not sure its that conductive but I'll try. It sure looks like two separate materials for the barrel bracing and the barrel itself will bring a lot of interesting options to the table.
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Post by Durandal on Mar 17, 2017 20:52:44 GMT
Ah, that is a little pricy. What was the average distance you tested at? Engagement range or did you use a laser for target finding? I'm curious about how that dispersal holds up at Mm range.
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Post by concretedonkey on Mar 17, 2017 20:56:50 GMT
All tests are at 1000km. Here is the gun:
RailgunModule Clean Railgun 1g 182t 15MW 20km/s
UsesCustomName true
PowerConsumption_W 1.5e+007
Capacitor
Count 1
DielectricComposition Mica
Dimensions_m 1.9 0.33
Separation_m 1.8e-006
Rails
Composition Osmium
Thickness_m 0.073
Length_m 1.9
BarrelArmorThickness_m 1
Armature
Composition Vanadium Chromium Steel
BoreRadius_m 0.00267
Mass_kg 0.001
Tracer Hematite
Payload null
Loader
PowerConsumption_W 1.5e+007
Turret
InnerRadius_m 1.6
Extruded true
ArmorComposition Aramid Fiber
ArmorThickness_m 0.03
MomentumWheels
Composition Zinc
RotationalSpeed_RPM 190
AttachedAmmoBay
Capacity 50000
Stacks 1
TargetsShips true
TargetsShots true
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Post by Durandal on Mar 17, 2017 20:59:38 GMT
All tests are at 1000km. Here is the gun:
RailgunModule Clean Railgun 1g 182t 15MW 20km/s
UsesCustomName true
PowerConsumption_W 1.5e+007
Capacitor
Count 1
DielectricComposition Mica
Dimensions_m 1.9 0.33
Separation_m 1.8e-006
Rails
Composition Osmium
Thickness_m 0.073
Length_m 1.9
BarrelArmorThickness_m 1
Armature
Composition Vanadium Chromium Steel
BoreRadius_m 0.00267
Mass_kg 0.001
Tracer Hematite
Payload null
Loader
PowerConsumption_W 1.5e+007
Turret
InnerRadius_m 1.6
Extruded true
ArmorComposition Aramid Fiber
ArmorThickness_m 0.03
MomentumWheels
Composition Zinc
RotationalSpeed_RPM 190
AttachedAmmoBay
Capacity 50000
Stacks 1
TargetsShips true
TargetsShots true
Thank you, I'll give it a shot (or two) later tonught.
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Post by concretedonkey on Mar 17, 2017 21:05:14 GMT
No problem. this is firing at a redesigned gunship at around 700kms you can see that even the ricochets are in one stream....
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Post by RiftandRend on Mar 17, 2017 22:13:22 GMT
Osmium is one of the least flexible materials in existence due to its density. I highly doubt that this accuracy is due to a bug. Also, I optimized your Osmium barreled railgun.
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Post by concretedonkey on Mar 17, 2017 22:34:34 GMT
Osmium is one of the least flexible materials in existence due to its density. I highly doubt that this accuracy is due to a bug. Also, I optimized your Osmium barreled railgun. Sorry to say it but your optimization ruins the accuracy. Additional barrel bracing is what i makes you ultra accurate ... I've gone a bit different way with the optimization - less speed... : Edit: The new gun has even tighter grouping, I guess because of the shorter barrel. You can clearly see that below the particles the impacts are a thin line... at 1000 km.
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Post by RiftandRend on Mar 17, 2017 22:51:11 GMT
Osmium is one of the least flexible materials in existence due to its density. I highly doubt that this accuracy is due to a bug. Also, I optimized your Osmium barreled railgun.
Sorry to say it but your optimization ruins the accuracy. Additional barrel bracing is what i makes you ultra accurate ... I've gone a bit different way with the optimization - less speed... Ahh, I missed the point. The Bracing is adding extra stiffness beyond what is shown in the designer. This is probably a bug then, either with the designer or barrel bracing.
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Post by concretedonkey on Mar 17, 2017 22:55:00 GMT
Sorry to say it but your optimization ruins the accuracy. Additional barrel bracing is what i makes you ultra accurate ... I've gone a bit different way with the optimization - less speed... Ahh, I missed the point. The Bracing is adding extra stiffness beyond what is shown in the designer. This is probably a bug then, either with the designer or barrel bracing. I sure hope its a bug in the designer not in the accuracy
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Post by RiftandRend on Mar 17, 2017 23:29:01 GMT
What's the cost on your new version compared to the original? You can use the compare new/original feature to show all of a systems stats in one screen like I did.
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Post by vegemeister on Mar 18, 2017 1:04:40 GMT
One way to examine dispersion without testing in combat is to hover your mouse over the bottom-left corner of the range graph, to show the tooltip on the very first data point. For example, you can see the range against targets with a cross sectional area of 0.0712 m². You can resize the sidebar to make the graph wider and check the range against even smaller targets. If increasing the thickness of the barrel armor improves the range against a target, you're dispersion-limited at that cross-section. If it doesn't, you're velocity-limited. The relevant material properties here are Young's modulus and density. Young's modulus is a measure of how much force it takes to stretch the material by a particular amount. Density is actually bad, because material farther from the bore stretches more when the barrel bends, and so you want the barrel as girthy as possible. Lower density means you can do that with less mass. Osmium has very high Young's modulus, but its density is also huge. Hafnium carbide is usually superior. It has nearly half the density, but the elastic modulus is only a little bit lower, and it's twice as conductive. Kind of weak, though, and more expensive. Beryllium is extremely good, but expensive. Also its yield strength sucks, so you may end up yield-limited rather than stiffness-limited. You can also just stick with aluminum copper lithium and pile the barrel armor on thick. (Aluminum zinc magnesium has an extra zero in the Young's modulus, so only use it if you don't care about realism.) Amorphous carbon is incredibly good on elastic modulus and density, but it's not conductive enough for rail guns. You can use it for coil guns though, but until capacitor voltage can be set per-stage, or somebody figures out how to get decent efficiency out of what we've got, they have to have very few stages (<3) or be line-powered. The 1 GW limit means line-powered coil guns can only achieve high velocities with super-light projectiles, and have to have very long barrels. That works against the stiffness of amorphous carbon, but they can still be made with very low dispersion. Example.
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Post by RiftandRend on Mar 18, 2017 1:57:35 GMT
One way to examine dispersion without testing in combat is to hover your mouse over the bottom-left corner of the range graph, to show the tooltip on the very first data point. For example, you can see the range against targets with a cross sectional area of 0.0712 m². You can resize the sidebar to make the graph wider and check the range against even smaller targets. If increasing the thickness of the barrel armor improves the range against a target, you're dispersion-limited at that cross-section. If it doesn't, you're velocity-limited. The relevant material properties here are Young's modulus and density. Young's modulus is a measure of how much force it takes to stretch the material by a particular amount. Density is actually bad, because material farther from the bore stretches more when the barrel bends, and so you want the barrel as girthy as possible. Lower density means you can do that with less mass. Osmium has very high Young's modulus, but its density is also huge. Hafnium carbide is usually superior. It has nearly half the density, but the elastic modulus is only a little bit lower, and it's twice as conductive. Kind of weak, though, and more expensive. Beryllium is extremely good, but expensive. Also its yield strength sucks, so you may end up yield-limited rather than stiffness-limited. You can also just stick with aluminum copper lithium and pile the barrel armor on thick. (Aluminum zinc magnesium has an extra zero in the Young's modulus, so only use it if you don't care about realism.) Amorphous carbon is incredibly good on elastic modulus and density, but it's not conductive enough for rail guns. You can use it for coil guns though, but until capacitor voltage can be set per-stage, or somebody figures out how to get decent efficiency out of what we've got, they have to have very few stages (<3) or be line-powered. The 1 GW limit means line-powered coil guns can only achieve high velocities with super-light projectiles, and have to have very long barrels. That works against the stiffness of amorphous carbon, but they can still be made with very low dispersion. Example. Thanks for the tips, they were very helpful. I have found Titanium Diboride to be an effective substitute for Osmium in some cases.
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Post by concretedonkey on Mar 18, 2017 7:43:16 GMT
What's the cost on your new version compared to the original? You can use the compare new/original feature to show all of a systems stats in one screen like I did. sorry I usually copy the gun do tests and then tweak again and so on untill I get something worth posting. So the compare will show just minor changes from the last iteration not the major step from the last version. The new one is around 2.5Mc. Keep in mind that I changed it a bit from what I had when the shot was posted so its not exactly the same. The new one is 10MWs across the board (reloading , rails and wheels) with a small hit in the fire rate. vegemeister , I'll test with hafnium carbide and see what happens. Also I'll test if reducing the bracing untill it doesn't reduce the accuracy against minial crosssection of the graph will reduce the practical accuracy in the tests. Yesterday's tests were all done with maximum bracing to test if it actually does anything if its not registered on UI and for the moment I think it does.
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