"Damage from APCR rounds" Topic

I've wondered just how much damage the core penetrator form an anti-tank round would cause after it penetrates.

From what I can find the penetrators are about 1/3 the diameter of the gun they are fired from and generally weight about 1kg with no HE charge. Typical 75mm AP round would weigh 6-7kg and have a HE charge in the base.

Does anyone have historical evidence of internal damage they cause or if they were likely to break apart?

Wolfhag

The primary advantage is that the entire weight of the penetrator core is in the center, so it's really more like getting hit by a ~25mm slug at ludicrous speed than by a 75mm.

It's effective enough, since the A10's 30mm uses a DU core in an aluminum jacket. No, it's NOT APDS, it's HVAP/APCR. Airplane engines don't like the idea of of ammo sabots going through them!

For the crew, you get a bunch of splinters from their own armor whizzing around at high speed – they are glass hard and razor sharp. There may be some bigger pieces of armor knocked off bouncing around at several hundred FPS, plus the core – APCR cores were steel, not Tungsten Carbide – which probably didn't have enough energy to exit the far side, so it also went careening around inside, to the detriment of radios and loose ammo. If they were unlucky, the tracer element might also go through the hole or sparks from ricocheting fragments could start a fire in ruptured ammo, fuel or whatever.

Tungsten cores are said to break-up or shatter going through the armor so that once they emerge on the inside the fragments cause casualties. They apparently still function as a penetrator while in the armor. It does seem there is less chance of the tank brewing up than with a full size shell especially APHE.

From Modern tests I read on penetrations from tungsten long-rod penetrators in Military Technology magazine. The effect of penetration on the inside of a AFV is like a small grenade going off at the inside surface of the armor. (The article was advocating Kevlar sheet lining on the inside of AFVs.)

APCR probably would be scaled back from this result as the velocities are less but personnel would be at risk.

Early war APCR had hardened steel cores but they were replaced by tungsten-carbide cores. This was rare and a limiting factor so there always shortages of these type of projectiles.

Interesting discussion here:
link

Expanding on the 57mm report does give some specifics.

And there is this official study Comparative Effectiveness Of Armor Defeating Ammunition out of Aberdeen in 1951
PDF link

Reminds me of a scene in the movie Patton, where Bradley says he asked one of his men if the German guns could penetrate the armor on American tanks. The GI said, according to Bradley, "No, they just come in one side and rattle around a bit."

Thanks for the research info.

I'm using the shell weight in kg as a modifier for the variable damage to internal systems. Since most 75-85mm shells weigh 6-9 kg and an APCR penetrator about 1 kg there should be a big difference in internal damage. It seems like an APCR penetration with the penetrator breaking up seems more similar to very serious spalling damage which can kill the crew without causing catastropic damage. That's what I'm aiming for anyhow.

Wolfhag

I would guess its a matter of chance. I remember reading about an Israeli Centurion being penetrated such that the APDS-FS went in the front and out the back of the turret leaving small notches where the fins were. This must of been steel penetrators from a T-62. I don't think the Russians sold 115mm tungsten penetrators before the 1973 war. In this case the sabot didn't breakup.

But a steel penetrator would have to be able to go through 152+90mm of armor.

Mobius,
The modern APDS-FS are a different beast compared to the WWII APCR I'm trying to model:

76.2mm APCR: 27.94mm tungsten core diameter, 0.48 kg core weigh

57mm APCR: 24.13mm tungsten core diameter, 0.51 kg core weight.

U.S. 76mm HVAP: 38.1mm core diameter, 1.76 kg core weight

These WWII penetrators are barely bigger than my thumb or big toe. I've checked some other games and on their damage table, they show a 10-20% chance of APCR causing no damage. Some of the video games have a fair % of no effect either even after penetration. I'd expect it would have some effect even if disrupting the crew and delaying them in performing their next action.

Wolfhag

I think I read that those little rounds tended to ricochet around the inside of armored vehicles, when/if they penetrated, causing casualties and additional damage.

I read in one account that even an 88 round can penetrate and do no damage. One Sheman was penetrated in and out with no effect. The writer noted that he ran a piece of string between the entry and exit and it should have passed through his knee however for whatever reason it did no dammage. So Occationally any round could penetrate and not be effective, However I agree that this is not statisticaly useful.

Thresher,
I imagine they would. However, as Mobius said, they tended to break up when passing through the armor because they were so brittle. Either way, they'll most likely cause causalities and disrupt the crew. In the close confines of a tank, more than one crew member would be affected. I just have not been able to find any first hand or historical accounts.

Wolfhag

I don't know if you want to complicate your game with modifying factors as armor thickness to shell penetration potential. Remember the case where Shermans in the Pacific had to switch to firing HE at the light Japanese tanks because their AP would go right through them and not stop them. APCR against thin armor should do even less damage as the armor punched out of the hole is so very little. APCR punching through thick armor would punch out more armor to throw around inside the tank.

The modern APDS-FS are a different beast compared to the WWII APCR I'm trying to model:

…

U.S. 76mm HVAP: 38.1mm core diameter, 1.76 kg core weight

These WWII penetrators are barely bigger than my thumb or big toe.

Ahem.

Got a pretty big big toe there, do ya?

Modern long rod penetrators for guns in the 100 – 105mm range are typically about 35 – 40mm in diameter. 115 – 120mm penetrators are typically about 40 – 45mm.

The difference is not too great. At least in diameter. If anything, the US 76mm HVAP looks a bit big, while the 76.2mm APCR (Soviet "arrowhead"?) looks more appropriately scaled in size compared to the gun's caliber.

But diameter is not really the main issue of differences in these "beasts". The real difference is velocity, mass, and the corresponding energy on target.

Any tanker I have asked has always expressed genuine disapproval of anyone punching holes through his office walls. When those holes are punched through with very high velocities, all kinds of bad stuff happens inside. Spalling, and the shot itself entering the crew's working space (whether as a whole or in pieces) means all sorts of soft bits (radios, ammunition cartridges, crew members, etc) will get shredded. Also, heat is a by-product of friction, and there is no path by which you can pass a metal object through another metal object without generating a lot of friction (a LOT of friction), so those little bits that go flying around inside the tank will probably be far beyond the combustion temperatures of the various soft bits they come into (and out of) contact with.

This friction heat is the main source of damage in penetrators. We're talking about spitting a Kg or two of white hot metal bits out of a 2 inch barrel (the channel through the armor) at higher velocities than most shotguns.

Yes, crew members survived penetrations. But it messed sh!t up left and right.

Or so I've read and been told.

-Mark
(aka Mk 1)

Mobius: I'm hoping to not make it difficult or complicated.
I'm exploring the ways that APCR failed so it does not be a "Silver Bullet" in the game. Like UshCha's account of an 88mm APCR round that is 30mm in diameter and weighed about 4kg.

Mark: my thumb is 25x75mm, big toe is 30x60mm. No, you can't see a picture. Compare that to the core/penetrator, not the entire shell.

You gave an excellent description of the modern APFS rounds but I posted this in the WWII section not the Ultramodern as the modern APFS are completely different as you stated. The APFSDS can have an MV of 3x+ of the WWII APCR rounds and the long rod concentrated many more times the energy too. The DU rounds have a completely different effect on armor penetration than normal rounds too. Modern APFS are almost always fatal to the entire crew, no argument from me there. From what I've gathered so far WWII APCR was much less lethal and that's what I'm trying to understand.

If you look at the images the core/penetrator, that's what does the damage, it's not the entire "arrowhead" of the round. It's kind of hard to believe they are so small but the diagrams don't lie. But being so small and brittle it's no wonder they break up while penetrating through the armor.

High armor angles and high velocity cause a lateral force on the nose which can shear it off (shatter gap).

50 mm Pzgr.40 and 40/1 21 mm diameter and 75 mm long tungsten cores.

From some reports, I read from metallurgists that have worked with this stuff confirm the core breaking up much of the time which is why there may not be much damage unless you happen to be directly in the way.

Early sub-caliber cores or penetrators are usually made from tungsten carbide sintered using nickel or cobalt as the bonding agent or binder. Its main advantage is its high density, ranging from 14.3g/cc to 16.3g/cc compared with 7.85g/cc for steel (and 1g/cc for water); and also its high hardness, ranging from 900 to 1,800 VDH compared with 850 VDH (about 739 BHN, the highest BHN possible) for hardened shot steel.7 Tungsten carbide has a high compressive strength and is two to three times as rigid as steel. Its high wear resistance makes it particularly useful as a cutting surface for machine tools. Industrial use was so important that when Germany was cut off from tungsten supplies the production of sub-caliber cores ceased and over half of the existing stockpiles were put into storage for future industrial use.

Tungsten carbide is relatively brittle and as a result penetrators made of it break up as they pierce armor, creating a highly lethal spray of particles. However this brittleness also causes them to fracture when they strike armor obliquely, so that their armor piercing performance falls off appreciably as the slope of the target armor increases. Against spaced armor the penetrator invariably breaks up completely after passing through the first plate, and the fragments tend to disperse before striking the second plate. This can be reduced but not eliminated by sheathing the core with steel, but this was only done by Britain in World War II.

Krupp experimented with tungsten cores from 1929 and limited production of such cores for infantry ammunition began in 1933. Krupp emphasized high density as the key requirement for the core, resulting in a high proportion of tungsten, but found that for cores of 15mm diameter and larger tungsten carbide sintered using nickel was needed to increase toughness and reduce the tendency to shatter. A typical German core has 93% tungsten, 5% carbon and 1% nickel.

German requirements for the hardness of cores were 1,725–1,800 VDH for cores used in guns up to 50mm, and 1,410–1,460 VDH for cores used in larger guns. Actual hardness measured by the USA of smaller cores averaged 1,365 VDH. German cores were 34–43% of the diameter of the gun caliber, with later versions of ammunition tending to increase the percentage ratio to improve penetration

Soviet cores were also high in tungsten content, but to save on its use their 76mm projectile had a two-piece core, with the forward part of tungsten and the rear part of nickel. The core's lesser weight understandably reduced its penetration. A typical Soviet core has 89% tungsten, 6% carbon and 4% nickel, has a hardness of 900–1,200 VDH and is 36% of the diameter of the gun caliber.

The British stressed toughness over density in the design of their cores. Thus the proportion of tungsten was reduced, and cobalt was used instead of nickel as a bonding agent. British research indicated that 50% of the gun caliber was a better size for the core diameter, and all British cores were sheathed in steel to reduce shatter against spaced armor and highly oblique targets. A typical British core has 82% tungsten, 5% carbon and 12% cobalt, has a hardness of 1,150–1,400 VDH8 and is 45–50% of the diameter of the gun caliber.

Wolfhag

Tungsten Carbide is going to strike all sorts of sparks off the inside of the tank, not to mention is going to be red-hot. That's going to do ugly things to hydraulics, fuel, or ammo. It's actually going to do less damage to the crew.

modern depleted uranium APFSDS raises that to another level, because uranium is pyrophoric (catches on fire in air!)

World of Tanks and Warthunder model the damage such that the AP shells fragment at the inside of the armor, so a side hit may catch 2-3 crew in the fragments.