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Post by caiaphas on Jan 4, 2017 13:14:01 GMT
yea... wipples don't do anything at all vs high velocity rounds... if I remember correctly wipple shields have a peak efficiency against projectiles of 10km/s and loose 15% efficiency for every 5km/s over that here is a gallery of my testing vs 130km/s 600mg rail gun boat composite - my normal Di/AMc(gap)/Bo/Ggel/Os Pure Wipple - 4x1cm wipple AMc(g)/AMc/Ggel/AMc(g)/AMC Altered Wipple - Diamond coated filled wipple Di/AMc/Ggel/AMC(g)/Bo Nitrile onion - NIrubber onion armour NIr(g)/NIr(g)/NIr(g)/NIr(g)/AMc imgur.com/a/itOPRbasic summary: any armour with Di/AMc coating managed to quite happily bounce all the needles and survived indefinitely (over 5000 rounds no damage) any armour without Di/AMc coating was shredded only composite armour managed to survive being shot by both needle guns and nuke cannons intact ...so many guns. EDIT: Oh, right, what mass rounds do you need to start chucking before it starts getting through the armor? I'm assuming that middleweight 10 to 20-kilo KKVs are the baseline?
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Post by newageofpower on Jan 4, 2017 13:49:18 GMT
EDIT: Oh, right, what mass rounds do you need to start chucking before it starts getting through the armor? I'm assuming that middleweight 10 to 20-kilo KKVs are the baseline? A few thousand (perhaps tens of thousands depending on hit angle) rounds of high velocity 1g sand will chew through even sloped amimai composite; the majority will bounce, but the energy transfer still occurs, and enough will not bounce. So going to a heavy kill vehicle is unnecessary.
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Post by Enderminion on Jan 4, 2017 20:04:08 GMT
EDIT: Oh, right, what mass rounds do you need to start chucking before it starts getting through the armor? I'm assuming that middleweight 10 to 20-kilo KKVs are the baseline? A few thousand (perhaps tens of thousands depending on hit angle) rounds of high velocity 1g sand will chew through even sloped amimai composite; the majority will bounce, but the energy transfer still occurs, and enough will not bounce. So going to a heavy kill vehicle is unnecessary. Ammo, do you have tens of thousands of rounds to waste like that
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Post by newageofpower on Jan 4, 2017 20:20:26 GMT
Ammo, do you have tens of thousands of rounds to waste like that Dude, the rounds are literally 1 gram ea. For a single 10-20kg vehicle I can carry 10-20k 1 gram rounds...
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Post by David367th on Jan 4, 2017 20:27:43 GMT
A few thousand (perhaps tens of thousands depending on hit angle) rounds of high velocity 1g sand will chew through even sloped amimai composite; the majority will bounce, but the energy transfer still occurs, and enough will not bounce. So going to a heavy kill vehicle is unnecessary. Ammo, do you have tens of thousands of rounds to waste like that Ammo doesn't really get expensive or heavy until you start getting into big armor piercing coilguns, like the 300mm stock design.
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Post by caiaphas on Jan 4, 2017 20:38:58 GMT
Ammo, do you have tens of thousands of rounds to waste like that Ammo doesn't really get expensive or heavy until you start getting into big armor piercing coilguns, like the 300mm stock design. Especially since a heavy KKV can run into the kilo-credits per shot depending on choice of material, rocket, fuel, armor, et cetera, while a one-gram chip of amorphous carbon is literally only 22.4 milli-creds. On that scale you could throw around fifty thousand shots before the KKV coilgun started being cost-effective. As for the physical size, some of my smaller PD railgun ship designs carry around a million rounds in a space smaller than one of the crew compartments.
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Post by caiaphas on Jan 4, 2017 20:48:33 GMT
EDIT: Oh, right, what mass rounds do you need to start chucking before it starts getting through the armor? I'm assuming that middleweight 10 to 20-kilo KKVs are the baseline? A few thousand (perhaps tens of thousands depending on hit angle) rounds of high velocity 1g sand will chew through even sloped amimai composite; the majority will bounce, but the energy transfer still occurs, and enough will not bounce. So going to a heavy kill vehicle is unnecessary. To be honest, with my preferred tactical doctrine (stay well outside of their range and murder them to death before they can start shooting at me), my primary consideration is still going to be "how long is it going to take for these railguns to shoot these thousands upon thousands of rounds, and is it going to be enough time for them to close the distance and murder me to death". So shooting off projectiles that can guarantee a kill with, theoretically, only a few dozen direct hits and will at the same time draw off enemy fire still feels like the better option to me.
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Post by kitten on Jan 4, 2017 22:45:19 GMT
Those are your sub-gram designs though aren't they? A whipple shield worth it's weight would gobble them like nothing. My osmium needles destroy whipple shielded craft (one passed through a stock gunship's nose armor and exited through an engine nozzle), but tend to do nothing (maybe leave a small glowing circle upon impact) against heavy monolithic plate. I suspect at sufficiently high velocities, the plasma (which the whipple shield shocks the projectile) into doesn't have time to disperse and is still fairly dense. Any criticism of the simulation aside, the most basic properties of Whipple shielding require a greater standoff distance as the density and speed of the impactor increase. The problem being that, say, a 10m standoff adds a huge ammount of cross-section and scales up the mass of your bumper (despite it being thin) considerably. And that's within the parameters of the simulation—IRL you'd have an engineering challenge to attach the shielding without a massive structure, yet in a way that it doesn't just tear off under the stresses of acceleration and impacts. Still, the basic concept of Whipple shielding—although it's probably more appropriate to say spaced armour at this point—is very useful (IRL at least) against high-velocity, low mass penetrators. I'm rather disapointed by how it works out in game, although it's worth pointing out that Amimai's composites are essentially "stuffed whipples".
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Post by David367th on Jan 4, 2017 23:28:26 GMT
My osmium needles destroy whipple shielded craft (one passed through a stock gunship's nose armor and exited through an engine nozzle), but tend to do nothing (maybe leave a small glowing circle upon impact) against heavy monolithic plate. I suspect at sufficiently high velocities, the plasma (which the whipple shield shocks the projectile) into doesn't have time to disperse and is still fairly dense. Any criticism of the simulation aside, the most basic properties of Whipple shielding require a greater standoff distance as the density and speed of the impactor increase. The problem being that, say, a 10m standoff adds a huge ammount of cross-section and scales up the mass of your bumper (despite it being thin) considerably. And that's within the parameters of the simulation—IRL you'd have an engineering challenge to attach the shielding without a massive structure, yet in a way that it doesn't just tear off under the stresses of acceleration and impacts. Still, the basic concept of Whipple shielding—although it's probably more appropriate to say spaced armour at this point—is very useful (IRL at least) against high-velocity, low mass penetrators. I'm rather disapointed by how it works out in game, although it's worth pointing out that Amimai's composites are essentially "stuffed whipples". If you've seen a video or pictures of whipple shields in action, generally the projectile stays in a spherical shape after the shield, probably still putting a lot of pressure on the pressure wall. 3M themselves have shown that normal single layer aluminum whipple shields can't stop 1g of aluminum going 6 km/s, and they've shown that their stuffed whipple shield design spreads out plasma further.
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Post by Enderminion on Jan 5, 2017 16:14:10 GMT
would DU needles not do more damage because they are incendiary and self-sharpening
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Post by coaxjack on Jan 5, 2017 16:39:09 GMT
Depleted uranium is only pyrophoric in the presence of oxygen, and at the speeds typical of guns in this game I doubt the self sharpening properties would come into effect before the round was pulverized into plasma by the impact.
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Post by Enderminion on Jan 5, 2017 19:34:16 GMT
Depleted uranium is only pyrophoric in the presence of oxygen, and at the speeds typical of guns in this game I doubt the self sharpening properties would come into effect before the round was pulverized into plasma by the impact. Worth a shot if it hits a crew module, any point is better then no point
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Post by dwwolf on Jan 5, 2017 21:10:56 GMT
Its only a concern with regular cannons. Once you get above the speed of sound in a material funky things start to happen. In the 1.5 km/s region that happens in steel and not in the DU penetrator.
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Post by lieste on Jan 5, 2017 21:19:53 GMT
Dense/needle like projectiles are only useful at ordnance velocities, and the much overstated 'self sharpening' of DU amounts to only modest benefits at between roughly 0.8 and 1.5km/s. Beyond that it mushrooms during penetration and has no advantage over a WHA rod at the same energy density.
By the time you are at 20-80km/s the type of material is almost irrelevant, only the mass and total energy involved, and to a limited extent the frontal area - though the smaller projectiles will instantly flow as a plasma.
DU is insanely expensive (ironic really given the huge quantity likely to be produced as a side effect of fulfilling all the requirements for 97% U235/U233 for the hyperoptimised warheads and reactors...) and broadly equivalent results should be seen with any of the cheaper materials.
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Post by kitten on Jan 5, 2017 22:10:44 GMT
Depleted uranium is only pyrophoric in the presence of oxygen, and at the speeds typical of guns in this game I doubt the self sharpening properties would come into effect before the round was pulverized into plasma by the impact. Worth a shot if it hits a crew module, any point is better then no point Not necessarily, a point can be brittle and break (which, besides losing any benefits of the point, absorbs some of the KE which you want to transmit to the target—an ideal projectile suffers zero transformations and converts all its KE into effects on the target, but that's obviously not possible). At the velocities we're looking at in CoaDE, even for chemical-energy guns, impacts are very violent and release a lot of pressure and heat. The shape of the impactor has limited relevance because both the impactor and target suffer a lot of transformation in a very short time, often including state changes (vapourisation, ionisation...). A pointy shape is helpful for less violent impacts, which can be more like cutting or shearing, especially when the projectile is harder than the target. DU is insanely expensive (ironic really given the huge quantity likely to be produced as a side effect of fulfilling all the requirements for 97% U235/U233 for the hyperoptimised warheads and reactors...) and broadly equivalent results should be seen with any of the cheaper materials. DU is relatively inexpensive; the main reason it is used IRL (despite the controversies) is that it is much cheaper than tungsten, with similar properties. Otherwise I think you somewhat understate density and thermodynamic properties for projectiles. Shooting helium is going to be less effective than shooting tungsten for the same mass and energy.
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