Non Capped AP(BC) shells need overhaul in WT

[Laurelix]

Currently in game, AP rounds are more likely to bounce against sloped armour than APCR rounds. If you don’t believe me, take a look at the stat card and it will say 50% chance of bounce against armour at 60 degrees whereas APCR gets only 50% chance of bounce once the angle is 70 degrees. This means AP bounces more against sloped armour than APCR which should not be the case considering it denormalises less than APCR.

Moving on… Non Capped AP rounds tend to deform against thick flat armour since they lack a piercing cap to absorb the initial impact by transferring the shock from the tip to the body, hence protecting the penetrator tip and increasing the ensuing penetration. The issue is that gaijin is using AP slope modifier found in WWII Ballistics: Armour and Gunnery with the post deformation penetration of AP rounds at 0 degrees instead of the true full penetration potential value at 0 degrees which matters because at high obliquity plates, the impact shock is lower and the shock hits the body rather than the tip flat on hence why deformation of the penetrator no longer occurs. Due to using lower 0 value to calculate sloped penetration, the sloped penetration figures end up being too low against sloped armour.

For Example According to the British the full true penetration of 2 Pounder AP (40mm, 1.08kg penetrator) at 792m/s is 90mm at 0 degrees.

Source:

If we use this as reference in Demarre Equation for 90mm T33 APBC which is a 10.61kg penetrator + 0.3kg windshield at 853m/s, the full true penetration of this round is 215mm at 0 degrees

Result:

T33 APBC penetration according to Terminal Ballistics is only 165mm at 0 degrees at 853m/s, however this is with deformation of the round included. War Thunder Penetration Calculator gives it 175mm at 0 degrees.

HOWEVER, Terminal Ballistics ALSO rates the 90mm T33 to penetrate 97mm of armour at 55 degrees at 853m/s.

Here are the AP slope modifiers from WWII Ballistics Armour and Gunnery.

Now we will see which of these 0 values is accurate in calculating 90mm T33 AP(BC) sloped penetration at 55 degrees.
165mm (Terminal Ballistics Volume III)
175mm (War Thunder AP pen calculator)
215mm (Full Potential penetration, Brit criteria)

According to Terminal Ballistics, the 55 degree penetration at 853m/s is 97mm which gives the 90mm round the capability to penetrate Panther Upper plate past 1000 meters.

T/D Ratio (Thickness Divided by Diameter)
97mm / 90mm = 1.0777

So 1.0777 T/D ratio at 55 degrees gives us a slope modifier of 2.21

97mm at 55 degrees x 2.21 slope modifier = 214mm at 0 degrees.

CLEARLY, the correct number to calculate AP sloped penetration is the full penetration potential value rather than the penetration at 0 degrees after AP shell deforms, because at high obliquities when it does not deform it does reach its full potential. The achieved penetration at 0 degrees after the round deforms DOES NOT represent the true penetration capability of the round. Using 165mm or 175mm instead to calculate sloped penetration at high obliquity will only yield underperforming values because essentially all that gaijin is doing is making non capped AP rounds deform equally as much at high obliquity as when they strike thick flat armour at 0 degrees, hence why currently AP shells underperform in WT which means non capped shells like T33 AP(BC) can’t penetrate Panther Upper Plate like it should and could do in real life and when you add that the unreasonable RNG value of 50% chance of bounce at 60 degrees, it makes AP rounds feel like Popcorn Dispensers instead of actual capable Penetrators against sloped armour where they should be excelling.

According to US tests in a declassified report from November 1951 ‘Comparative Effectiveness of Armour Defeating Ammunition’ it states the superiority of AP shells performance against armour sloped at higher obliquity compared to APC shells however also the superiority of APC rounds against flat armour compared to AP rounds.

APC rounds feature piercing cap at the cost of a smaller penetrator resulting in lower kinetic energy and upon impact some of the energy is further absorbed by the piercing cap against the sloped armour yielding inferior performance to the AP round. AP rounds do not have the piercing cap hence why their penetrator is bigger and also there is no piercing cap getting in the way of the armour and the penetrator. However despite the fact APC round have smaller penetrator, the piercing cap stops the penetrator deforming against thick flat armour, increasing the ensuing penetration, yielding superior flat penetration compared to non capped AP rounds.

Full Source Here:

ADA954868.pdf

Changes that should be made:

Non Capped AP / APBC rounds should no longer deform at high obliquity. 0-37 degrees they should deform like normal. 37-53 should be the middle ground, from 37 to 53 the deformation should gradually become less and less as the angle increases and anything after 52 degrees, the sloped penetration should be calculated using the “full potential penetration” which is 215mm for T33 APBC at 853m/s or 90mm for 2 Pounder AP at 792m/s

As for those who still do not believe that T33 AP(BC) is capable of over 210mm penetration.

90mm M82 APCBC at 853m/s in WT has 185mm at 10m penetration

90mm T33 APBC - Look how much bigger the penetrator size is compared to M82 APCBC, the penetrator not only is longer than M82, it has no HE filler cavity inside, further increasing the penetrator volume and weight which increases the Kinetic Energy of the round.

It should be no surprise that 90mm T33 APBC penetrated Panther upper plate (80-85mm at 55 degrees) reliably at 1000m, whilst the M82 couldn’t whatsoever. T33 AP(BC) penetrator is literally 2.78 calibers (250mm) in length compared to M82 APCBC penetrator length at only 2.413 calibers (217mm). Also again I want to emphasise the fact that instead of a big non penetrator cavity filled with explosive filler that M82 has, the T33 is a full on solid penetrator slug without a cavity that could of been a penetrator, again reducing the actual overall weight of the penetrator on M82, and T33 having a much heavier penetrator.

Successful penetration of Panther Upper plate with T33 APBC

full source here:
https://www.lonesentry.com/manuals/90-mm-ammunition/index.html

Non Capped AP rounds chance of bouncing is far too high, 50% of the time at 60 degrees makes no sense. They shouldn’t be prone to bouncing more than APCR. Considering WWII ballistics slope modifier doesn’t put AP/APBC at 4.0 slope modifier until 68 degrees at 1:1 T/D ratio, I don’t see why gaijin can’t increase the 50% chance of bounce probability to 68-70 degrees instead of 60.

If you’re still not convinced for fixing the rounds, then here’s another reason. It would add another skill element to the game, knowing when it’s better to use AP round and when it’s better to use APC round instead of just using APC 24/7 because it’s better in every regard over AP rounds in game right now.

To support the overhaul give us a thumbs up on the bug report
https://community.gaijin.net/issues/p/warthunder/i/hLPH8HLThguu

[Laurelix]

Full Potential Penetration of non Capped Shells when they don’t deform at 0 degrees.

US:
75mm M72 AP = 114mm @ 0m
76.2mm M79 AP = 168mm @ 0m
90mm T77 AP = 204mm @ 0m
90mm T33 APBC = 215mm @ 0m
120mm M358 APBC = 395mm @ 0m

USSR:
85mm BR-365K AP = 184mm @ 0m
100mm BR-412 AP = 273mm @ 0m
122mm BR-471 AP = 257mm @ 0m

UK:
2 Pounder AP = 90mm @ 0m
2 Pounder AP(HV) = 100mm @ 0m
6 Pounder AP L/45 = 137mm @ 0m
6 Pounder AP L/52 = 146mm @ 0m
77mm QF AP = 181mm @ 0m
17 Pounder AP = 215mm @ 0m

Japan:
47mm Type 1 AP = 99mm @ 0m
75mm Tokku Ko AP L/38 = 136mm @ 0m
75mm Tokku Ko AP L/56 = 185mm @ 0m
90mm M318A1 APBC = 237mm @ 0m
105mm Type 2 AP = 306mm @ 0m

NOTE
These non capped rounds deform at 0 degrees so they don’t actually achieve this penetration however since deformation at high obliquity does not occur, their 50-52+ degree penetration should be calculated as if they could achieve the penetration figures above at 0 degrees.

[Wallia_Marseille]

Great to see you here trying to make Gaijin fix AP.
I sadly think that were going totally opposite direction that these your findings show.
I have quite a while been noticing Gaijin trying to make shells worse rather then better. Might be just me but all the changes to APDS and AP shattering, HEAT-FS damage getting nerfed even the mighty APHE feeling weaker and filler explosion dissapearing to void when hitting certain parts.

I don’t know is the reason just make rounds “More realistic” or are they trying to make WT more new player friendly where you don’t get killed by first round every time.
At least I feel like im having to spent much more shells then previous and getting lot more of these “Gaijined” moments where I or somebody else gets killed by round not doing what it was expected to do.

But I hope that Gaijin finally fixes AP using data that you have collected over the years.

[SpardaSon21]

One thing I’d like to add is that starting with the T33 onwards US shells were made out of steel that had been heat-treated exceptionally well that further reduced deformation, even against flat armor.

[MiseryIndex556]

T33 was reheat treated M77 and that actually may have cause it’s shattering issues. Here’s a chart I have showing AP vs APC and AP outperformed APC against 0 degree and 30 degree plates. APC retained its energy better due to the ballistic caps.

[SpardaSon21]

Yes, early solid shells like M77 lacked caps or ballistic caps, but the T33 did have a ballistic cap.

[FlipAllTheTables]

Interesting. If I didn’t make any mistakes reading this graph, a capped round and an uncapped round with the same 0º pen also end up with the same 30º pen. In-game that’s not the case, generally speaking uncapped rounds have worse 30º slope modifiers.

[MiseryIndex556]

@SpardaSon21

Yes, early solid shells like M77 lacked caps or ballistic caps, but the T33 did have a ballistic cap.

Yeah, I know. My point is AP generally outperformed APC, unless the AP round shattered like T33. If the AP rounds had ballistic caps, they would outperform APC at all ranges.

[MiseryIndex556]

AP actually has slightly better slope modifiers than APC.

[FlipAllTheTables]

These are not slope modifiers themselves, and while the ‘a’ value is generally lower at the 30º range, the ‘b’ value is noticeable higher, which means that against undermatched armor the AP round will perform worse, and better against overmatched armor.

Using Desmos we can determine that the AP and APC rounds end up with the pretty much the same 30º slope modifier at a T/D ratio of 1.3347, with AP being better if below, and worse if above. WarThunder uses D/T instead, so that would be basically 0.75 in-game. Red line is AP, blue line is APC, as seen from the respective 30º formulas on the top left.

Using 90 mm early M82 APC(BC) and T33 AP(BC) in-game, T33 has a higher 30º slope modifier compared to early M82 at point blank, with 175/132 mm and 173/133 mm of pen respectively at 0º/30º, although T33 will gain the advantage as the penetration decreases. Using the value of 1.3347 and the respective 1.2909 slope modifier, the 30º slope modifier is the same for M82 and T33 once their 0º penetration reaches roughly 155 mm, with 120 mm of 30º penetration for both rounds. I confirmed this using the T-54 (1947)'s UFP, which is 120 mm thick, and using it in protection analysis at 30º gave 155 mm of effective protection for both T33 and M82.

With the US 76 mm cannon, the break even 0º penetration is 130.95 mm, and basically the same for the US 75 mm, at 129.22 mm. However with these cannons the APC round just has massively improved penetration over the uncapped AP round, so the APC ends up with always higher 30º pen at all distances and this comparison becomes a bit pointless, which is why I used T33 and early M82 in my comparison as they have very similar flat penetration values

[MiseryIndex556]

Thats a good point. I only calculated the modifiers for 1 T/D and didn’t take the exponent into account.

[KillaKiwi]

@FlipAllTheTables

Interesting. If I didn’t make any mistakes reading this graph, a capped round and an uncapped round with the same 0º pen also end up with the same 30º pen. In-game that’s not the case, generally speaking uncapped rounds have worse 30º slope modifiers.

@MiseryIndex556

Yeah, I know. My point is AP generally outperformed APC, unless the AP round shattered like T33. If the AP rounds had ballistic caps, they would outperform APC at all ranges.

I think in that case it’s because US APC kinda sucked. They appear to be designed to defeat FHA rather than to retain good penetration over AP at 30° impact angles.

76.2mm M79 is superior in penetrating a Tigers front plate even at 30°.
Had the Tiger used FHA however, then the M62 would be effective at much longer ranges compared to the M79.

[MiseryIndex556]

To an extent, sure but even if you compare it to 75mm PzGr 39/42 DeMarre to the same velocity, M72 would out perform it by around 10mm.

[Bruce_R1]

I would like to hear from a community leader why this entire discussion isn’t a violation of new forum rule 3.6: ““reporting game bugs, errors, or other flaws is not permitted.” Seems to be a pretty flagrant violation. (Link)

I don’t want to stop the conversation, just wanting clarification before I risk my community rating participating as a community member in discussions like this.

[scorpian]

Gaijin has a very spotty track record when it comes to modelling shell shattering. Even before the calculator was implemented, Gaijin still gutted the T33s flat pen to realistic standards because of histroical accuracy. But, despite a bible worths of information made on the forum and suggestions the sloped pen was never touched on. The 90mm does seem very much under lock and key because Gaijin has very much deemed it ‘historically accurate’.

Anyways, the other issue is that only Soviet APHE is allowed almost borderline absurd sloped performance. If other nations were allowed usuable sloped performance, tanks like the T-44 wouldnt be such a balancing nightmare.

In a sense, it seems that soviet midtiers was specifically designed to have this ‘gimmick’ of superb sloped performance. Having uncapped AP shells creep over the soviet gimmick is completely unacceptable. After all this is what makes soviet shells ‘unique’.

[poopooo]

One question, which tanks had face hardened armor? Supposedly the hull front of the tiger 1 was not from FHA? And also the T34 were not made with FHA?

[SpardaSon21]

The Germans were really the only ones who used FHA. It works best against impacts of relatively low obliquity (such as with vertical armor plates). However when impacted at an oblique angle such as when you use sloped armor even if the harder front blocks the shell through ricochet or shatter the kinetic energy of the impact has a tendency to cause the softer rear to fly off as internal spalling.

As an (extreme) example, the French battleship Dunkerque had face-hardened armor on her turret tops to protect against AP bombs from aircraft, which meant that when Hood bounced a 15" shell off the top at Mers-el-Kebir the resulting spalling was bad enough to ignite the powder stored in that side of the turret, killing the crew from asphyxiation, as well as completely disable the right-most gun, only the internal bulkheads keeping the guns and crew in the left side of the turret safe.

[KillaKiwi]

Both Pz III and IV used FHA for most of their armor. Probably the Pz II as well.

T-34 and IS tanks had HHA, while pretty much any other tank used RHA or CHA.

80mm FHA should protect against medium velocity 75mm AP projectiles so APC enabled Shermans to destroy Pz IVs even at long range.
A 100mm FHA plate would probably also protect against high velocity 75/76mm AP shells except from the 17pdr.

So 76mm APC was pretty much only required, had either Tiger or Panther used FHA for their 100mm thick armor plates. Since they didn’t, M79 AP was the superior shell.

90mm M82 is the same story. It’s pretty much inferior against any known target compared to M77, unless a vehicle had used >100mm FHA plates.

[KillaKiwi]

@SpardaSon21

The Germans were really the only ones who used FHA.

I think Japan also used them for their tanks. Certainly for armor plates inside planes, afaik.

[poopooo]

So not even the most initial tigers had the heat treatment on the front of the hull?