Is it possible that 310 grams is the slug of steel behind the core? Say you project the core diameter through the steel base, is that close to the 310 grams?
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Here is how it would look like:
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This model predicts that against thin plates this shell will have much lower ballistic limit than DeMarre equation predicts. I’ve selected the penetration points between 300 - 500m as reference, as we know that in real life tests this shell perforates between 100 and 80mm at 500m distance.
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@Conraire Since no weapon fires bare tungsten cores, the eventual contribution of the mass of base plug to penetration is already implicitly accounted in penetration curves. So I don’t believe the solution is to add some extra mass to the projectile.
Almost all conventional HVAP designs have the weight of the base roughly equal to the weight of the core, but in the soviet 76 and 85mm APCR this mass is about 6 times the greater than that of the core alone.
Edit:
@Conraire You were looking for information on soviet 85mm post-war HVAP shells? I’ve tried looking as well, no luck so far. Found FT for the D-44 gun. This shell is mentioned there, has velocity vs distance data for it.
Look, if we assume that the tungsten core of BR-367P is proportioned like that of the US 90mm HVAP, we can estimate its penetration and compare that to historical data:
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BR-367P, from what I’ve gathered, basically copies the design of late, German HVAP-like rounds.
The pictures I’ve seen online all show the same blueprint with the half cut, so it’s a bit more difficult to make pixel measurements. Nevertheless, doing the pixel measurements that I can using this diagram, it seems that the core is roughly 135 mm long, and 35 mm wide.
Edit: I will add that BR-367P in WarThunder has a 30 mm wide core, weighting 1.1 kg.
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That’s what I initially thought, expecting the soviet shell to be essentially an up-scaled 7.5cm PzGr.40, but after running some calculations, I’ve realized that you can’t achieve 200mm+ of pen at 500m with such small core, and only 1020m/s of muzzle velocity.
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Here is why I believe the soviets went with a heavier core for this shell: when you’re shooting a tank, as long as your penetration is less than it’s armour thickness, your attack is about equally effective whatever your penetration is.
So it stands that instead of peppering the target with weak attacks you want to use the strongest attack possible. This is doubly so with tungsten ammo, as you don’t want to waste it on ineffective attacks. So, if your heavy HVAP shell will reliably penetrate target’s armour and disable it in 1-2 hits, you will actually save tungsten as a result, as opposed to if you were shooting dozens of weaker shells that could disable the target only if they’d hit a weak spot like the turret ring, joint between two plates etc…
I’m taking an educated guess. Going by the cutaway design from that manual page for BR-367P, it appears to be a copy of 88mm PzGr40. Using the core mass and diameter from 88mm pzgr40 with the velocities for 85mm BR-367P on the 2C6 Calc results in this under the natural brinell hardness curve for the calc… That compares exceptionally close to the values from the German manual for the gun.
Core Mass: 4.25lb(1.927kg)
Core Diameter: 1.42in(36mm)
Mass in Flight: 11.68lb(5.30kg)
85mm BR-367P
Muzzle = 1020m/s
100m = 997m/s
500m = 909m/s
1000m = 803m/s
1500m = 705m/s
2000m = 612m/s
Vertical
10m = 258mm
100m = 249mm
500m = 216mm
1000m = 176mm
1500m = 143mm
2000m = 113mm
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Is the carrier weight included in any way or is that just the core?
No, with that particular design, the carrier probably wouldn’t contribute much at all. So it’s just from the core.
So it would be comparable to early US APCR?
Hey boi, look what I found:
Compared to BR-365P, the BR-367P projectile has an even smaller elongation of 3.0 calibers, though it was still somewhat heavier overall due to the larger core. Its tungsten carbide core is 35mm in diameter and 140mm long, giving it an aspect ratio of 4.0. It weighs 1.6 kg, which is more than twice the weight of the BR-365P core while the weight of the complete projectile inceased only slightly to 5.3 kg. However, the weight of the core was still lighter than the core of the M93, which weighed 1.79 kg (3.95 lbs). The BR-367P tungsten carbide core shared the same aspect ratio as the 76.2mm BR-354N core, developed in conjunction with BR-367P and sharing the same design features but scaled for a smaller and less powerful gun.
Muzzle velocity: 1,020 m/s
Cartridge weight 11.72 kg
Projectile weight: 5.35 kg
Propellant charge weight: 2.5 kg
Overall projectile length: 255mm
Core diameter: 35mm
Core length: 140mm
Core weight: 1.6 kg
Source: Tankograd: Soviet Towed Anti-Tank Guns
He doesn’t give his sources, so take this information with a grain of salt.
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35×140 is nearly the same as 88mm pzgr40 core, which is 36×140 iirc… I can probably bug him on discord to figure out the source for the info.
Yeah, but the 8.8cm PzGr.40 core weights about 2000g, not anywhere close to 1.6kg figure he’s reporting on his blog.
Edit: He probably just measured the drawing and took it at face value.
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The reason why you can’t is because they only existed in a proof of concept phase for tests leading up to APFSDS (called HVAP-DS equiv. historically).
Neither «УБР-412П» nor «УБР-365П» were produced for any period of time, and as far as testing and accounts of use, I doubt there was more than 100 of either shot.
First, HVAPDS is the american name for APDS, and not APFSDS.
Secondly, if the 85mm BR-365P round was experimental, then why examples of it were captured in the field during the Korean war? Why was data for it present in soviet firing tables? Why germans were able to get their hand on some in 1961?
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As I said, the translation to English conforms most closely to the definition of HVAP-DS, as that was the nature of Soviet and German APDS.
Nobody mentioned APFSDS.
Examples? I don’t see any.
Because… It was tested and later overshadowed by APFSDS?
That’s ripped directly from a random forum, and here is the statement verbatim
“According to him these two pages are from a 1961 german report. He said nothing else about it and didn’t respond when another user asked to see the full document, but he left these performance figures derived from live firings…”
There is then an image copy/pasted from a Tankograd forum.
Did you forget that Germany was a pivotal portion of the SSSR from 1954-1979? Especially in development, and they were the hosts of countless training grounds for T-62 and T-64 crews, as well as research and development.
Why wouldn’t they have a diagram of these?
Which APDS is this, T137 or T65?