Good news, I found this useful fragment of physics lore I had lying around:
we can use it to estimate the m.v. of the 37mm subcaliber shell without the LJ adapter:
Almost right on money! It seems that the adapter doesn’t add much, if any extra velocity to the shell that is not already achieved just through it’s smaller mass.
It’s wonderful to see how you can’t kill a BMP completely from the side by shooting at point-blank range. Or how it can’t break cannons or tracks, unless you spend more than 100 bullets per module.
It really is a shame what gaijin does with certain weapons, and precisely the Marder A1 and the Ratel 20 have both of the two worst weapons in the game.
By the way, how is it possible that the Marder A3 does not have the Milan 2, when in reality it used it, so they could raise the Br of that Marder a little more.
I got my hands on a scan of a soviet technical report describing the work performed between Jan to March 1942 on the development of subcaliber shells for their 45mm tank/anti-tank guns.
To avoid boring you with the technical details, I’ll just translate the ballistic tests performed against manufactured armour plates. They were carried out from a 65m distance using adjusted propellant load to get desired striking velocity:
Projectile: design No.2. Tungsten carbide core of ogival shape. Weight (kg): 0,800.
Armor plate: 50mm, face-hardened.
Obliquity: 30°.
Striking Velocity(m/s): 797 and 801.
Equivalent distance(m): approx. 450m.
Result: “Armor pe[unintelligible]. Hole, 25-40; 20-[unintelligible]. Core [unintelligible]. In the plywood behind the plate hole 80x100mm. [unintelligible] impact struck [unintelligible]”
Armor plate: 60mm, not face-hardened.
Obliquity: 30°.
Striking Velocity(m/s): 832,6 and 839,3.
Equivalent distance(m): approx. 380m.
Result: “Armor perforated. Hole diameter 25-35; 20-35mm. Core fractured into fragments. In the plywood hole 50x80mm from the first shot and 80x80mm from the second one.”
Armor plate: 60mm, face-hardened.
Obliquity: 30°.
Striking Velocity(m/s): 932,4 and 902,4.
Equivalent distance(m): approx. 250m.
Result: “Armor perforated. Hole diameter 20-50; 20-18mm. Core fractured into fragments.”
Armor plate: 100mm, not face-hardened.
Obliquity: 0°.
Striking Velocity(m/s): full propellant load 0,374kg.
Distance(m): 65m
Result: “Armor perforated. Hole caliber sized.”
We can compare these results with the rated armor penetration of this gun from the official soviet source:
So, its simply worse compared to 5 cm Pzgr.40?
Worse? Well it’s a 45mm shell fired at 1070m/s, vs 50mm shell fired at 1180 or 1130m/s. What did you expect?
Edit: Here what they look like if we use the same model to estimate their performance, to remove the influence of extraneous variables:
What about compared to the 1050m/s Pzgr.40 0,925kg of the KwK 38?
I would like to compare the performance of US 76mm HVAP vs the german 75mm APCR to analyze different philosophies of their design.
See new graph.
The relative weakness of the german 75mm APCR is not due to bad design of the shell, as germans technically could’ve used a heavier tungsten core to increase it’s armor penetration, but is a deliberate choice as it was merely meant to offer a fighting chance against armored targets, that are armoured enough to make the full caliber shells from this gun ineffective against them (which is about 110mm/30°). Against even more heavily armored targets, other, heavier guns, like the Nashorn’s 88mm were supposed to take care of them.
While the US subcaliber shell was designed to, quite simply, achieve the higher possible armor penetration performance from this gun.
@Ghostmaxi Subtract 180m distance for the 5cm shell o account for lower m.v. It’s still slightly superior to the 45mm one.
Edit: My bad, the german 75mm APCR when fired from the L/48 gun had m.v. = 990m/s, not 930m/s.
See updated graph:
Today I just shot a DF105 from the side completely at about 30 meters, not a single bullet from the 20mm cannon entered, then I shot a Milan at the center of the tank and only killed the commander, immediately afterwards it killed me. Really War Thunder’s damage and penetration model is the biggest piece of garbage ever seen in a game.
I also manage to get a non pen on a 105 Sherman with French 90mm APCBC and non-penned a Ho-Ri Prototype with 90mm HEAT-FS with 350mm penetration because it hit the 150mm front plate at an angle, resulting in like 500-1000mm of armor, because the armor isn’t modeled volumetric, resulting in impossible armor values.
It’s so annoying.
That’s like a pixel size where the shell won’t pen.
On the topic of gameplay side of special amunition: if APCR/HVAP ever gets it’s real life penetration and be made adequately lethal in the context of WT gameplay, there will be a need to re-balance it. Otherwise everyone is gonna shoot it 90% of the time (except aganst tanks that have sloped armour everywhere).
I have previously suggested that only a limited amount of it be made available per vehicle AND that it cannot be replenished on cap circles.
My reasoning for the latter is: if once a given team controls the cap point, they get access to pretty much unlimited super shells from it, it’s gonna be even more difficult to dislodge them and re-cap it than it is now, worsening the tendency of GF RB matches to snowball into defeat once any team gain an advantage. I think we all agree that we prefer to play longer games where each team has a chance to turn things around and win at any stage of the match.
Also, from the gameplay perspective, the purpose of even having these special shells in the game is to give tanks a chance to make a difference, even when uptiered aganst significantly more powerful opponents, not to negate any armour and transform meta into “who’s got more crew members has more health points” system.
Also, making these shells limited in quantity is in line with historic reality.
Man, imagine special ammunition being actual effective, worth using and limited instead of spamming the best round like they built nothing else.
It also reminds me of air battles. The games been out for 11 years and they never bothered to add missing ammo types, like the HEI-T for Italian 12.7mm or APHE for MK 101/103s.
But now we can drop napalm on bases and use AP bombs that probably no one botheres to use.
I think I can see a pattern 🤔
If it’s a module to unlock that pays with money or playing time, regardless how useless it is, its worth implementing.
If that’s not the case, Devs don’t bother.
For Gaijin to feel compelled to make any changes, they probably need to make each ammo belt unlockable instead of all at once.
Then they will be like: Here are 5 new ammo types you can unlock.
One of the 3-4 Major version revisions of 90/40mm T320 ;). The version in game now, I believe is modeled after T320E10, which used an all steel penetrator.
Depends on the time frame, really. APCR was standard for the USA by Korea. Turns out that the richest country in the world has no problems firing wads of cash out of their tank guns instead of more conventional rounds.
Well, as tank armor got more effective it also become more expensive to deal with them :)
True, but even in Korea when the T-34/85 was the primary medium tank that the 90mm would have had no problems with we still shot APCR at them.
Of course if you were a Sherman crewman APCR was a godsend. Over 180mm of pen in the close fighting typical to the Korean mountains would let you blow a hole clean through any part of it.
People often assume that tungsten carbide projectiles are quite simply not susceptible to shatter, unlike the normal steel AP. It’s a widely held… misconception.
The truth is quite different:
The British report, EFFECT OF IMPACT AND VELOCITY, listed the results of APDS testing for shatter velocity, which was found to vary with angle.
Tungsten projectile shatter failure is based entirely on angle and velocity, as follows:
Impact Angle…critical velocity
0…4132 fps
5…3849
10…3792
15…3528
20…3472
25…3377
30…3321
35…3283
40…3264
45…3283
50…3340
55…3472
60…3623
You can observe this happening here in the velocity range predicted by british data. For lower hardness plate hits at around 3000fps don’t shatter but once they do the ballistic limits jumps upwards suddenly.
source: Shatter gap in uncapped AP shot. - Historical Discussion - War Thunder - Official Forum
Hey look what I found: the penetration for the 85mm BR-365P projectile differs in this table when compared to this other (later one).
Source: Firing Tables for the 85mm guns, 3-rd edition 22 February 1945.
Edit: interesting note:
“In this edition … is ascertained the armor penetration of the BR-365 and BR-365P projectiles and was added back the info on armor penetration of the BR-365K projectile”
Interesting. Why have they removed the data on pen of this shell from previous edition? Because from the context it sounds like it was present in the first edition of these tables.
I did look into it. :)
Now I’m back to share my findings: I have confirmed that the mass of the steel sheath(APDS)/carrier(HVAP) does indeed increase the armor penetration when compared to the core alone.
I have also developed a mathematical model to account for this effect.
Edit: Interestingly, if we try to apply this model to full caliber shells, lets say the 88mm Pzgr.39/43, and use the weight of the shell w/o cap and windshield (8.8kg) and set the contribution from the carrier to zero, we get pen of around 230mm/0° at 100m.
Edit:
Edit: Change K_0 to 1880 and U to 210 and n to 1.26
Edit: pls someone comment in this thread, the forum doesnt let me post more than 3 comments in a row.
Anyway, if this game will ever implement face-hardened armour, it will be only fair to properly model the soviet high-hardness armour as well.
And it’s much stronger against APCR than normal hardness RHA.
Very interesting formula, here’s your reply.
Link: https://apps.dtic.mil/sti/tr/pdf/ADA800130.pdf
These findings broadly match the information I’ve posted earlier.
