I have no idea.
So what does it say? :3
Nothing much, it briefly describes both AP and APCR shells and their effects on the target.
The pretty much only interesting part is the penetration values, first column is AP, the second one is subcaliber.
The document does not give the mass of the projectile, so I had to manually 3D model it to estimate its mass:
The performance of this shot aganst 0° target was significantly worse than expected from extrapolation ofother data. The expected BL against a 38,1mm/0° target is supposed to be around 2700fps. Something must be going on. Could be excessive yaw of the projectile, perhaps.
Idk, it’s a pretty light core.
Compared to 20mm AP →
A 20mm Pzgr. 40 core has almost twice the weight.
Resulting in 2" penetration when using the other tungsten core as reference.
Use real life data as a reference. In a 1943 test soviet 45mm APCR against Tiger I upper side (T/D = 4,1) obtained a ballistic limit of ~840m/s. This is a good ballistic limit from 8 shots, and the armor quality on that tank was pretty good, which gives us a good reference point to estimate the BL for the .40in.(10,16mm) core against a 38,1mm plate of 269-311 BHN used in that US test.
But you’re comparing arrowhead APCR rounds with a large steel sheath against the performance of just a tungsten core.
For the 45mm APCR the penetrator makes less than a 1/3 of the shell weight.
Obviously the steel sheath can not be entirely ignored.
That’s… actually a good point. I wasn’t considering the possibility that a different relative mass of the core carrier might change the ballistic limit in a significant way.
If your theory is correct, the APCR shells with higher fraction of their mass in the carrier would perform better, relative to the absolute mass of their tungsten cores.
I will look into this.
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Isn’t that how Gaijin sets up their formula?
Yes. They put a huge emphasis on the total weight of the shell so that Soviet APCR gets to their historical standard, which of course left everyone else behind who used APCR with heavier cores instead of the Soviet approach of saving as much resources as possible.
Easy fix would just be to have two formulas for APCR penetration. One that considers the total weight (arrowhead design) and another which mainly focuses on the penetrator.
Yes, and its a wrong approach. Watch carefully this video here:
Not all mass from the HVAP carrier is equal. Some of it slides off the sides of the core with negligeble effect on the penetration process. Some of it stays and pushes it into the target for an extended time. See the sketch here:
Spoiler
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For me the video doesnt work.
For me neither.
I used inspect element to get the video link. Here it is.
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Well, the ratio of carrier to core is pretty low in this example. So it’s almost neglectable.
While with this one it’s almost like those early Soviet steel rod APFSDS with a tiny tungsten core in the the front:
On the seond plate the core has slowed down but the sheath is still going faster, pushing the core further.
Then there are these amazing pieces of Soviet engineering:
20mm and 23mm BZ API for aircraft cannons.
These must get incredible instable after impact, tumbling and probably causing quite a lot of damage to spars and fuel tanks while having pretty good performance against light armor on the ground.
When compared to those soviet 76mm and 85mm unique APCR designs, sure, but you’ve said it yourself:
The base plate on the M93 HVAP is solid steel while the rest of the carrier is aluminum. It must contain about 50% of the total carrier’s mass. I will do the math tomorrow, but this might be enough to account for the ~300fps discrepancy in the ballistic limit for that .40 cal WC core test.
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