Post by AtomHeartDragon on Jul 19, 2020 9:36:37 GMT
We all know that melty, ductile Whipples are the best, so does meltiness of k-slugs (regular ones and shrapnel, not radshield cheese) negatively impact their peformance? Would, say, a hypervelocity 1kg of carbon, osmium or tungsten deal appreciably more damage even after shattering compared to usual steels?
Has anyone ran any regular tests?
Do note that "meltiness" includes a few disparate properties like melting temperature, heat of fusion and heat capacity, possibly also boiling temperature and heat of vaporization.
Basically does the game model bulkhead and underlying components getting shotgunned by fragmented k-slug as opposed to being only gently singed by vaporized one?
Another question - can shattering be beneficial in limiting overpenetration and leaving more kinetic energy in the target?
Post by doctorsquared on Jul 20, 2020 16:42:55 GMT
I’ve not run instrumented tests, but it would appear that the game’s model uses the tensile strength and force imparted by the projectile to determine if the k-slug overpenetrates or shatters. I’m unsure if fragmentation outside of flak is modeled, since the damage model seems to generate a mesh around the target and then uses the mechanical properties of the materials in the impacted volume to determine the effects.
Post by AtomHeartDragon on Jul 20, 2020 20:18:13 GMT
OTOH the game does seem to model different failure modes for armour, does seem to model spall and (empirically) ductile and melty whipple shields tend to perform better, so the question is whether those same effects are modeled for slug material and whether it matters.
That would be a good option. I've been playing around with the stock 60mm cannon and tested out Amorphous Carbon, Calcium, Copper, and the standard Tungsten rounds and haven't noticed much difference.
Stock 60mm actually doesn't have almost any penetration. It fires wafer-thin disks. Even depleted uranium isn't of much help here. The reason why it's contrary to gameplay experience is that stock 60mm is very fast and accurate so its slugs hit pretty much the exact same spot and effectively drill through armour.
Anyway, I'm attaching two railguns. One is good old 'Santa' firing coal amorphous carbon (that can also be gotten off Steam), the other is pretty much its equivalent, but firing maraging steel instead (based on jtyotjotjipaefvj redesign of 'Santa' - which is nice as I usually steal jt's guns instead ).
Both fire 1kg slugs at 20km/s (that's 200MJ of blam) at same rate of fire. Feel free to throttle them down to test at lower velocities.
Sadly they have different caliber, but that's not as easy to tweak as changing rate of fire.
Post by doctorsquared on Jul 23, 2020 21:36:00 GMT
Okay, so I took and made a Black Box weapon that fires a 1kg projectile at 20km/s at ~60 rounds per minute like the railgun in question. I then took the base Austenitic Stainless Steel and made a low melt temp (59K) and a high melt temp (4900K) version of each, so both have the same mechanical properties with different melting points. One (1) cannon was then fired at a stock Corvette using the Predatory Opportunism mission preset using the Instant Action option for 60 seconds. Range was ~100km, the weapon was set to distributed targeting with "ignore range" turned on in order to maximize odds of hitting armor rather than external modules.
Neither material showed signs of over penetration of the target. The backstop armor did have indicated damage on the model for both tests.
Total of 28 penetrations through the armor facing the cannon for the low temperature material, 19 penetrations for the high temperature. Differences would include target orientation and differences in perpendicular velocity versus the two targets.
Based upon the results it would appear that projectile melting point does not factor into penetration calculations at this projectile mass and muzzle velocity.
High Melt Temp Impact and Backstop
Low Melt Temp Impact and Backstop
Material Low Temperature Test Material Elements C Mn P S Si Cr Ni N Fe ElementCount .0008 .02 .0004 .0003 .0075 .20 .12 .0010 .65 Density_kg__m3 8030 YieldStrength_MPa 290 UltimateTensileStrength_MPa 621 YoungsModulus_GPa 193 ShearModulus_GPa 77 SpecificHeat_J__kg_K 500 MeltingPoint_K 59 ThermalConductivity_W__m_K 21.4 ThermalExpansion__K 9.4e-6 Resistivity_Ohm_m 116e-8 RelativePermeability 7 RefractiveIndex Iron RoughnessCoefficient .35
Material High Temperature Test Material Elements C Mn P S Si Cr Ni N Fe ElementCount .0008 .02 .0004 .0003 .0075 .20 .12 .0010 .65 Density_kg__m3 8030 YieldStrength_MPa 290 UltimateTensileStrength_MPa 621 YoungsModulus_GPa 193 ShearModulus_GPa 77 SpecificHeat_J__kg_K 500 MeltingPoint_K 4900 ThermalConductivity_W__m_K 21.4 ThermalExpansion__K 9.4e-6 Resistivity_Ohm_m 116e-8 RelativePermeability 7 RefractiveIndex Iron RoughnessCoefficient .35