47mm AT gun-pathetic after armour affects

[black_prince]

Last night I played a QB as Italians defending against Americans. At one point an advancing Stuart exposed its right side to one of my 47mm guns. The gun opened up at about 350 metres achieving eight penetrating hits in succession before the crew finally bailed out. However, the tank had not been knocked out or destroyed. Two other Stuarts also recieved multiple penetrating shots on the right side of their turrets and front of their turrets (possibly from a 47mm HEAT round?) and the original abandoned tank also recieved further occassional penetrating shots into its side. In addition, both of the latter Stuarts recieved a number of partial penetrations and spalling hits. By the end of the game a further Stuart had been abandoned and it transpired that all three had been immobilised. However, none of these tanks had been knocked out or destroyed in spite of multiple penetrating hits to their hulls and turrets.

I am a little surprised that any armoured vehicle of the period should survive so many penetrating hits. Even if the 47mm rounds are modelled as solid shot with no bursting charge (although the graphical depiction of their impacts would certainly suggest otherwise) this doesn't seem right to me. Have other people had a similar experience with this gun and if so is there any historical justification for this?

[womble]

It's often difficult to know quite what's happened to AI vehicles. You eventually discovered that the "OK" tanks were immobilized, but I don't know how you can tell what system damage they've sustained, and you don't mention any crew casualties. There are tales of Shermans in the game surviving multiple penetrations from PaK38 with only single casualties (there's a comparatively large amount of empty space in a Sherman).

[Amizaur]

IMO behind-the-armor effects are too weak in the game. To achieve good chance of causing enemy crew casualties and firt-penetration knock-out you need very powerfull/energetic gun like 17pd or 88L71. Anything less (like 76mm, 75L48) achieves only medicore performance even against thin, side armor (thin enough, to ensure clean penetration with little loss of shell velocity, but thick enough - like 40-60mm - to produce good amounts of spall and shrapnel). Both kinetic effects and burst-charge effects (if they are modelled) seem undermodelled for me. It's a feeling based on in-game observations and knowledge of numerous tanker memoirs, statistics, and physics.

Some testing I've done showed number of casualties in Shermans almost as high as historically documented, BUT I used solely 88L56 to achieve penetrations, and only against Shermans. My later game experience showed that less powerfull guns achieve much lower casualty rate (extreme example being those 47mm guns), and that German tanks like Panthers/Tigers seem to be more resistant (have lower chance of casuality happening if penetrated). So - overall - the casuality rate is too low IMO and the formulas used should be revised. Especially in case of side penetrations.

[Michael Emrys]

I don't know about all of that. I've seen enough pics of tanks with multiple penetrations that I would want to see some official statistics on the average number of penetrations required to get a definite kill before I committed to a position on this issue.

Michael

[Baneman]

... There are tales of Shermans in the game surviving multiple penetrations from PaK38 with only single casualties (there's a comparatively large amount of empty space in a Sherman).

PAK38 ? Phooey, small beer. I've had a Panther put 5 penetrations into a Sherman which then killed the Panther

Empty space ? I think the crew were remote operating it !

I don't know about all of that. I've seen enough pics of tanks with multiple penetrations that I would want to see some official statistics on the average number of penetrations required to get a definite kill before I committed to a position on this issue.

Multiple penetrations doesn't mean the first hit didn't knock it out, it just means the enemy weren't sure.

Most of the tanker memoirs I've read pretty much had them bailing out as a matter of course, if they were penetrated at all.

[black_prince]

It's often difficult to know quite what's happened to AI vehicles. You eventually discovered that the "OK" tanks were immobilized, but I don't know how you can tell what system damage they've sustained, and you don't mention any crew casualties. There are tales of Shermans in the game surviving multiple penetrations from PaK38 with only single casualties (there's a comparatively large amount of empty space in a Sherman).

You can check the systems report for enemy vehicles after the mission ends. The second abandoned tank (front and side turret penetrations) had red tracks and radio but all other systems were green, didn't check the first tank which took the most penetrating hits. Crew casualties were 2 each in the case of both abandoned tanks.

I've seen plenty of pictures of tanks with multiple penetrations as well (although I don't know wether or not they were still in a good running state. IIRC correctly I have also read an acount of a British tank crew in North Africa continuing to fight their tank after it had been penetrated by an AP shell and one of the crew having been severely wounded. However, I was very surprised that the little M5a1s were able to survive penetrating hit after penetrating hit in the way I described. Obviously the versions of the Stuart used in game are mature versions of the tank so it is possible that they have an improved internal layout (well protected fuel and ammo stores). But it still seems a little odd to me. TBH, I don't feel confident enough to say definitively wether or not these results are true to life or not. I've had a quick look to see if I can find anything relating to the survivability of tanks after a penetrating hit from a gun of similar caliber but havn't found anything useful so far. I'll also carry out some tests to see how repeatable this is when I have a little more time but I was hoping to hear other people's opinions and experiences with regard to this in the meantime.

[womble]

PAK38 ? Phooey, small beer. I've had a Panther put 5 penetrations into a Sherman which then killed the Panther

Heh. Yeah. I think the most I've seen one take from a Panther is 3, and certainly still be in a fighting condition (it backed off behind smoke, then reappeared and blew up some infantry before the AT assets nailed it).

Given how powerful AT shells are when they burst in the open after overpenetrations or ricochets, I'm surprised any tank crew ever survives if the burster charge goes off. Regardless of clever layout stuff.

[Baneman]

Hehe, it may have wanted to back off, but one of the shots must have immobilised it as it never moved again.

It actually survived a 6th :eek: penetration from a schreck I then crept up to it, but the 7th finally convinced the crew to go away. It was a real thorn in my side though !

[black_prince]

Given how powerful AT shells are when they burst in the open after overpenetrations or ricochets, I'm surprised any tank crew ever survives if the burster charge goes off. Regardless of clever layout stuff.

Good point.

[MikeyD]

I tried looking it up on the net and failed. Does anybody know if 47mm AP had a burster charge, or was it solid shot? British 2 pounder (40mm) didn't have a burster charge, I believe.

[akd]

Italian 47mm AP had a 0.030 kg TNT bursting charge according to TM 9-1985-6.

[Amizaur]

Calibers like 37mm, 45mm, 47mm, 50mm needed burst charges to be more effective. Basing solely on kinetic effects they were able to knock out enemy tank (kill or injure it's crew) but often it took multiple penetrations. With good and working burst charge shells like German 50mm were said to be MUCH more effective after penetration and capable of one-shot knock-outs, especially if the penetration was barely achieved, with such low energy that it had small chance to be effective.

The caliber, muzzle velocity and energy of AP shells were raising quickly and soon shells like high-velocity 75/76mm were effective ENOUGH with only kinetic energy, and guns like 88L71, 17pd and probably 75L70 as well were penetrating with such velocity and energy that burster would not add much to the equation.

On the other hand, IF equipped with working bursters those rounds were even more deadly and effective, detonation of the burster was increasing number of shrapnel, chances for fuel or ammo ignition, was creating deadly overpressure peak that alone could kill in confined space, and filled the inside of the penetrated crew compartment with thick smoke from detonation products...

Those additional effects increased casualties, but - even if burster detonation didn't add much ENERGY to the total equation (the kinetic energy was far greater), then I guess that it greatly increased chances for making the crew of penetrated tank willing to abandon it (because of all this explosion, shock, burns, wounds, perforated eardrums, smoke, maybe fire ect).

Sometimes I find amazing that anyone was able to survive detonation of medium size burster inside a buttoned tank, in a cramped space filled with mechanisms, human bodies, lots of ammo cartridges and sometimes even fuel tanks (T-34), with not much free space and the crewmembers relatively close to each other. If typical burster of medium-caliber AT round had 30-60g of HE, then it's like a defensive fragmentation hand grenade detonating INSIDE of the tank - with smaller number of fragments, but similar HE effect.

I guess that at least some of the survivors had enough luck that burster of the penetrating shell for some reason didn't detonate, so they only experienced kinetic effects.

[John Kettler]

black-prince,

The Italian 47mm antitank gun fired two separate and distinct antitank rounds. One was kinetic, the other HEAT, know to the Italians as E.P., Effeto Pronto. The velocity delta between the two rounds is enormous.

http://en.wikipedia.org/wiki/Cannone_da_47/32_M35

The Wiki doesn't list the HEAT penetration figure, but it's pretty attention getting--112mm

http://www.miniatures.de/shells-italian.html

By contrast, the 1942 intelligence report seems woefully confused. 2 pdr AT guns had NO HE round, nor were they fitted with and kind of APHE, firing solid shot exclusively.

http://www.lonesentry.com/articles/ttt08/italian-47mm-antitank-gun.html

There may be a translation error here, but the use of the term "AP grenade" would appear to suggest the AP projectile explodes, making it APHE even if not so labeled, mimicking U.S. practice.

http://www.waroverholland.nl/index.php?page=47-mm-at-gun-pag

I was right. AP shell! Page 26 here is dispositive and includes a cutaway section. Handbook of Enemy Ammunition, Pamphlet 7

http://www.scribd.com/doc/52183493/2/ITALIAN-47-32-CARTRIDGE-Q-F-A-P-WITH-TRACER-FUZE

I quote myself in an excerpt from a much longer post lamentably lost in the Great Server Meltdown. The combat lethality of even the German 37mm AP shell was high if even a partial penetration of the fighting compartment could be achieved.

"It was not until 1942 did the British investigate the high incidence of fires in British tanks post penetration. Major G.B. Jarrett in May 1942: “The German projectiles which have caused the greatest amount of damage to allied tank in the western desert campaigns have been the A.P.-H.E. type in 47mm, 50mm, 75mm and 88mm respectively. These projectiles at long range need only attain a partial penetration and the explosive charge can complete the destruction of at least the tank crew. At closer ranges the destructive effect is very great, where in many cases destruction of the tank is permanent.”……….. Of those mark III and IV knocked out in combat by AP-shot, fewer than 20 percent were destroyed by fire or damaged so severely that they couldn’t be repaired."

--------------------------------------------------------------------------------------------------

Every now and then I get really lucky. Here is Jeff Duquette's detailed post to me with all the pertinent data. (Fair Use)

http://www.battlefront.com/community/showthread.php?t=50874&highlight=2pdr&page=4

Hey John K:

Some of what you maybe recalling might have been from your readings in Jentz. There is a reference by Jentz to G/B Jerratt (I have included it with the other scanned material below).

Best Regards

Jeff

From: Thomas Jentz “Tank Combat in North Africa, The Opening Rounds”. Schiffer Publishing Limited, 1998

From Page-44

4.1.1.1 BRITISH GUNS AGAINST AXIS TANKS

Directly after the battle of Beda Fomm, the 2nd R.T.R. conducted tests to determine the vulnerability of the Italian M. 13-40 tanks. They reported on 14 February 1941: During the morning tests were carried of the effect of the two types of 2-pounder ammunition on Italian M13 tanks. These tests proved that the yellow painted explosive armour piercing projectile penetrates the armour at 900 yards and bursts inside with very destructive effect. Sand bags placed on the crew's seats were well riddled with splinters. The black painted solid A.P. projectile also penetrates at 900 yards and causes large cracks in the armor.

From Pages 46-47

4.1.1.2 EFFECT AFTER PENETRATION

The destructive effect of the 2-pounder AP-Shot after penetration was based solely on whatever kinetic energy re¬mained in the solid shot, shot fragments if it shattered, and/or fragments of armor plate broken off by the hit. Starting with the design of the Pz.Kpfw.l, German designers had taken extra precautions to reduce the probability of fire as a result of penetration. Fuel tanks were separated from the crew com¬partment by a firewall (about 5 mm thick). In the case of the Pz.Kpfw.ll, the fuel tank, located on the right side of the crew i compartment, was isolated by 8 mm thick armor plate. As a further precaution, the main gun ammunition in the Pz.Kpfw.lll and IV was stowed in bins whose sides were 4 to 6 mm thick. In addition, main gun ammunition in the Pz.Kpfw.lll and IV was stored low in the hull. Thus, even when a 2-pounder AP-Shot managed to penetrate through the armor, it needed suf¬ficient residual kinetic energy to penetrate the firewall or am¬munition bins in order to destroy the tank by setting it on fire. Penetration of a Pz.Kpfw.lll or IV by 2-pounder AP-Shot fired at 600 to 1500 yards range frequently resulted in crew mem¬bers being wounded but infrequently resulted in destruction of the tank by causing irreparable damage or by setting it on fire. Of those Pz.Kpfw.lll and IV knocked out in combat by AP-Shot, fewer than 20 percent were destroyed by fire or damaged so severely that they couldn't be repaired.

====================================

Below is Jentz discussing German AP-HE projectiles – from pages 48-49.

====================================

As stated in a German report on armor-penetration curves: Basically all penetration data are valid for projectiles of good quality. The estimate of penetration for "worst" projectiles is possible only with great difficulty. The penetration can spread over a very large range below the given value. The regulations for acceptance of projectiles stipulate that a certain number of projectiles (1/2%) will be presented for inspection. Two-thirds of the projectiles which have been fired against armor plate, must satisfy the given conditions. Based on past experience, it can be stated that the largest part of the deliveries satisfy these conditions. 100% assurance is not given; it may always be expected that a small percentage do not achieve the specified penetrating ability, because of shattering prematurely. Also the explosive charge in these shattered projectiles will not detonate.

The effect of the projectile inside the tank and the probability of hitting the target are not considered in these graphical charts; thus only the complete penetration with the to¬tal effect inside the tank is considered. As a rule, this effect is of annihilating power when using armor-piercing shells with a high-explosive charge. When using hard core projec¬tiles, steel or soft iron core projectiles, or hollow-charge projectiles, completely annihilating effect cannot always be expected with a single shot, because the crew, located in the dead space of the tank, cannot be hit under certain conditions.

A limited effect, without piercing the tank by the projectile (effect produced by back-spalling of armor plate and punching holes (Stanzpfropfen) is frequently achieved with plates that are about 10% thicker than the thickness presented in the graphs.

AND from page 54

4.1.2.2 EFFECT AFTER PENETRATION

In all calibers of 3.7 cm and above, the normal armor-piercing round designed by the Germans contained a high explosive filler with a delay fuze. Penetration of a British tank by a German armor-piercing shell frequently resulted in crew members being wounded as well as destruction of the tank by causing irreparable damage or by setting it on fire. Not until 1942 did the British investigate the cause of fires in the tanks and began to install armored bins to protect the ammunition.

As recorded by Major G/B. Jarrett in May 1942: The German projectiles which have caused the greatest amount of damage to Allied tanks in the Western Desert campaigns have been the A. P. -H. E. type in 47 mm, 50 mm, 75 mm and 88 mm respectively. These projectiles at long ranges need only attain a partial penetration and the explosive charge can complete the destruction of at least the tank crew. At closer ranges the destructive effect is very great, where in many cases destruction of the tank is permanent.

When the 7.5 cm K.Gr.rot Pz. was fitted to an American casing and fired from the 75 mm M2 gun, in May 1942 Lt.Col. Gruver reported: Each German AP-HE round fired may safely be presumed to have put the tank out of action. In this con¬nection it was noted that the fuze functioned perfectly, that is to say it functioned only after penetration and then always in the fighting compartment where the most damage is done. Parts also frequently penetrated into the engine compartment.

The destructive effect of the Pzgr.40 after penetration was based solely on whatever kinetic energy remained in shot fragments when it shattered and/or fragments of armor plate broken off by the hit.

Jentz Refering to Italian AP-HE, page-57

4.1.3.2 EFFECT AFTER PENETRATION

The Italian 47 mm armor-piercing round contained a high explosive filler with a delay fuze. Penetration of a British tank by a 47 mm Italian armor piercing shell frequently resulted in crew members being wounded as well as destruction of the tank by causing irreparable damage or by setting it on fire.

__________________

Based on the above, especially the last paragraph, I find it amazing that five penetrating APHE hits into a gasoline powered tank wouldn't have K-Killed it. Recall that Jarrett said the same net result could be obtained from even a partial penetration of a 37mm APHE shell into the fighting compartment, followed by detonation.

The variable here is that there may have been improvements to the Stuart to change the basic vulnerability issues the tests and combat results highlighted in North Africa. This is presently beyond my knowledge base, but I'm betting someone has the right grog reference on the Stuart.

Regards,

John Kettler

[Cranky]

"By contrast, the 1942 intelligence report seems woefully confused. 2 pdr AT guns had NO HE round, nor were they fitted with and kind of APHE, firing solid shot exclusively."

Speaking of confusion:

About a week back, I got curious about the fact that in CMAK and CMBB the 2 pdr gun in tanks and armoured cars has a HE round available in the Editor after April 1943.

The default amount is 0, meaning that you have to add such rounds via the Editor - but they ARE available.

A couple of hours reading stuff on the internets produced a bunch of conflicting info -

An HE round was produced, but not issued, or an HE round was never made at all.

Some sources maintain that an APHE round was manufactured and issued from the late 1930's, but these rounds were quickly used up in the first 2 years of the war.

[black_prince]

John Kettler you are magnificent! Havn't had time to go through all of the sources you have provided in detail tonight as I am catching a flight tomorrow morning. However, I'll have a proper look and post here again in the next couple of days.

[MikeyD]

Italian 47mm AP had a 0.030 kg TNT bursting charge

I called on my trusty unit converted and found out that .03 kg was one ounce of TNT. That's a bit less than 1/10th the energy of a stick of dynamite. Only enough energy to crack the shell into fragments, I guess.

[John Kettler]

Cranky,

If this projectile is compatible, then I'd say you've made a discovery and that we've learned something new. No 2 pdr HE in the Western Desert, but it was apparently introduced later. Here it is.

http://en.wikipedia.org/wiki/File:QF2pdrVickersHVShell1943.jpg

Regards,

John Kettler

[John Kettler]

black_prince,

You're welcome! I considered myself fortunate to find that material, especially since I couldn't recall the location where the British ran their tests.

Regards,

John Kettler

[Cranky]

Mr Kettler -

That HE shell is for the 2 pdr Naval Gun - the QF Pom-Pom - so, as you say, it's a question of compatibility;

Whether

(a) you could fire such a shell from the 2 pdr AT gun - they are different weapons, the 2 pdr QF being an Autocannon.*

( if yes, did anyone actually do so?

And what about the mysterious APHE shell?

Clearly the Battlefront team must have had something in mind when they allowed for a HE shell to be available to 2 pdr AT guns in CMBB and CMAK, but what?

* I don't pretend to have any experience of such things, although I did once use a spud-gun to fire carrots, if this is applicable.

[Michael Emrys]

Clearly the Battlefront team must have had something in mind when they allowed for a HE shell to be available to 2 pdr AT guns in CMBB and CMAK, but what?

ISTR that an HE shell was available in time for Overlord to be used by such ACs as were still armed with the 2 pdr cannon. Is that correct?

Michael

[akd]

ISTR that an HE shell was available in time for Overlord to be used by such ACs as were still armed with the 2 pdr cannon. Is that correct?

Michael

Yes, which is why the Daimlers in CW module have HE.

[John Kettler]

Cranky,

The Wiki drawing proves you correct, but QF merely means Quick Firing, or semiautomatic, as opposed to, say a screw breech. The 2pr pom-pom is gravity fed and will fire as long as there's ammo and the firing pedal's depressed. The OQF (Ordnance Quick Firing) 2pr is not gravity fed but manually fed, and it is that gun that was fitted to the armored cars under discussion. so, we still don't know what the HE shell looked like.

Regards,

John Kettler

[John Kettler]

Michael Emrys,

This guy's quite the grog and indicates, unfortunately without giving the date or details, that an HE shell WAS eventually produced and deployed late in the game for the 2pr. Relevant paragraph's just below the pic of the Army 2pr.

http://www.quarry.nildram.co.uk/37-40mm.htm

Still looking for the bloody shell.

Regards,

John Kettler

[John Kettler]

I tried another approach, looking up a known 2pr equipped armored car, the Daimler. This isn't what I wanted, but it's really cool and should have grogs and mods needing incontinence garments!

http://www.daimler-fighting-vehicles.co.uk/DFV-File%20Part%20Be%20-%20History%20-%20WW2%20North%20Europe.pdf

Grog heaven! Daimler Mk I, II--in unbelievable detail! Gives 2 pr. ammo load, but not ammo types,let alone designations.

http://daimler-fighting-vehicles.co.uk/DFV-File%20Part%20Ah%20-%20DAC%20Data%20sheets.pdf

This is amazing, but unfortunately, it covers only the exterior. Need the part of the training film covering the interior!

Regards,

John Kettler

[John Kettler]

Cranky,

Forgot to mention a QF gun always fires fixed ammunition (no separately loaded shell and powder charge, even if it is in a cartridge brass). It's all one round, factory loaded and delivered to the field. Fuzing is a separate matter. HE could be set for a number of modes.

Regards,

John Kettler