So, I’ve been tinkering with the 2C6 Nomograph calculator recently. I figured out how much of the carrier mass from M304 is applied to the core during low obliquity angle penetration, and have it calibrated to match historic penetration results at firing table velocities for the M304/T30E16 round at 220bhn. If it’s not exactly on for the round, it’s within 1-2mm for the range table velocity.
It’s also quite useful, in the fact that once its calibrated to a specific round design. It can be used to determine a velocity table/curve for a round or rounds where little or no information is available, as long as there is some form of historic penetration data to go by.
For example, the T30E16 based 90mm HVAP rounds. Which would be M304(90mm M3 Gun), T44(90mm T15 Guns), and T44E2(90mm T54 Gun), all basically use the same 8lb core and base carrier design. The only differences may be in driving band placement. However, they all fire the rounds at different muzzle velocities.
90mm M3 Guns
M304 = 3350ft/s or 1021m/s
90mm T15 Guns
T44 = 3750ft/s or 1143m/s
90mm T54 Gun
T44E2 = 3875ft/s or 1181m/s
The constant with the T30E16 design is of course the as fired mass of 16.8lb or 7.62kg, 8lbs/3.628kg of which is the core, an unknown amount is the Steel base cap and tracer assembly, and the rest is the aluminum carrier and windshield. After subtracting the 8lbs from the core, that leaves 8.8lbs/3.992kg of carrier mass.
During calibration to M304, I found that, in order for the round to meet its historic performance levels at firing range table velocities, a penetration mass of 8.686lb/3.94kg was required. Which would mean, about 0.688lb/312g (7.81%) of the carrier mass are acting on the core, during initial penetration. Most of that is likely from the steel base section acting as a piston pushing on the core.
I’m not at home near my PC at the moment, so I’ll have to elaborate more later.
When estimating the performance of the APCR carrier, I used to just consider the steel weight behind the core. Both for simplicity sake but also since I knew that the total weight couldn’t be used, since not the full KE of the carrier would be transfered the core.
As you can see, during the initial penetration impact phase, the steel base section stays intact, pushing on the core until it hits the plate surface. And then a small portion of the carrier base breaks off and follows the core through the hole.
On the other hand, that also somewhat explains why those earlier HVAP/APCR rounds would be worse against sloped armor than an APDS round. As at angles above ~50-55° that base section would get deflected off the base off the core much sooner.
I believe the later rounds like M319, and M332 also benefit somewhat from the base piston effect as well, due to how the carrier is designed, even though the base is aluminum alloy.
Dejmian also made this simulation, using a supercharged M93 round versus a hypothetical armor set up of the Ferdinand using slopped spaced armor rather than 2 plates of armor stuck together.
One thing I want to point out is that according to him these armor plates are 80 mm at 55 degrees followed by 100 mm at 9 degrees. M93 just about managed to penetrate the first plate.
Obviously, this is just a simulation, so it’s not proof of anything, and this is being fired at a supercharged velocity. But I do remember something about the British figuring out that 17 pounder APDS needed over 3410 ft/s (1040 m/s) of velocity to defeat a Panther upper glacis. It seems that M93 follows that closely (and M93 has a very similar core to 17 pounder APDS, only slightly larger by 0.5 mm and heavier by around 0.02 kg) .
It could be that late war US APCR rounds follow a slope armor performance much more similar to early APDS rounds than what “WW2 Ballistics: Armor and Gunnery” states. This might be because navy criterion requires set amount of mass to pass through the plate, so penetrations like this weren’t considered? But I’m just throwing ideas out.
Wait so the M26E1 should fire APCR at a slightly higher speed?
If so, can a bug report be made on it? Not only the speed but also the name, since in game it’s just called “HVAP shot”. I feel like the ammunition names of the M26E1 could do with some love.
(Edit: I also am interested in the source since I always like expanding my library of knowledge)
Genuinley dont understand why gaijin made the shell penetration so bad and shatter so violently overcommon in such ammo, conveniently not allowing other shells prone to shattering to have the same mechanic
Remember, they don’t play their own game so they don’t even understand clearly how badly they’ve ruined alot of stuff in the game, though they’ve also made it pretty clear they don’t care either way.
Never. Changing bullet damage would fix a lot of the game’s issues and make it possible to rebalance most tanks in a more historical manner, but it would be a job for the developers that doesn’t generate any financial benefit. An update with 20 new vehicles, 8 of which are premium, is always better than fixing the game’s real issues without generating any financial benefit.
