Best Tank Destroyer/ self-propelled gun (1 Viewer)

the De-Marre formula assumes solid AP-shots without cap for a very narrow range of T/D ratios and obliquities.

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You are right,and my supplement is that: T/D ratio should be around 1.0, it can be 1.2 while De Marre's result is still quite accurate. The hitting velocity should be less than 1200m/s otherwise both amor and projectile will fall to pieces and the remain part of projectile will continue to penetrate the amor other than "throwing back". That's why modern APFSDS is more effective than WWII AP when facing slope amor.

There is another important concept: When a projectile double its KE, it just can NOT penetrate twice thickness of same quality amor. That is to say, ONE 200mm plate's stopping power is quite bigger than TWO 100mm plates in spite of what type the projectile is (AP,APCBC, APCR etc.)With regard to multi-layer amors, we can't add up each amor's thickness simply in order to get the total stopping power.It's a basic knowledge.

Kwk43's APCBC KE has 67% advantage on kwk36's, therefore, kwk43's penetration must be LESS than 200mm@100m since 120*167%=200.
Delcyros, I agree that if kwk43 apcbc's penetration is 200mm@100m, the target plate of kwk43 must be different from kwk36's.

I've got the answer! The thick target plates (>150mm even >200mm) are of inferior quality compared to thin plates(<150mm), therefore, those mighty guns' (such as 17 pdr,kwk43 ...)score is overvalued inevitably. This can perfectly explain why those guns are not sufficient when facing Panther D's glacis (80-85mm/55 degree) which is equivalent to "good-quality thick plate"(>150mm).

LOL

No Glen, the thicker plates were NOT of worse quality! The BHN level was just lower, which is completely normal. QUALITY DID NOT CHANGE.

Against WW2 AP projectiles the best armor BHR was 255 - 265 BHN, the level of the Tiger Ausf.E's armor, the same armor which managed to stop 76mm 77mm Allied AP projectiles at point blank range! Yet the 88mm KwK43 L/71 is capable of punching holes in this armor beyond 4 km if the thickness is 100mm! The KwK43 would punch through 100mm of 300 + BHN armor past 4km for crying out loud! The 122mm D-25T can hardly punch through 100mm of VERTICAL 240 BHN armor at 3km, the 88mm KwK36 L/56 being just ~10mm behind it.

And like Delcyros explains De marre's theory DOES NOT WORK for these projectiles! It works for solid shot AP projectiles, NOT APCBC, esp. not when slope is applied! The theory is from 1870 Glen! Not 60 years later when the APCBC projectile was introduced!

Also for the last time, the 88mm KwK43's APCBC projectile was designated Pzgr.39/43, NOT Pzgr.39-1, the 88mm KwK36's APCBC projectile was designated Pzgr.39-1!

Its time you get this into your head Glen, cause its getting really straining having to repeat it!

Soren
17pdr was also 76,2mm gun, and its APCBC round was definitely able to brew up Tiger I at medium ranges. Gordon's Firefly knocked out 4 Tiger Is in the battle in which Wittmann was killed and another Firefly brewed up 2 more, modesty claiming only 2 Pz IVs.
I also have seen too many photos of holes made by T-34's 76,2mm gun onto Tigers to take your claim too seriously.
That said IMHO Pz VI E was a good and effective tank but expensive to product.

Juha

I wasn't talking about the 17 pdr's APCBC projectile Juha, I was talking about its APDS projectile failing miserably at close range against the Tiger Ausf.E's armor. The US 76.2mm gun was even worse in this regard, WITH APCBC, as it often just shattered at point blank range. The US had previus to the introduction of the 76.2mm gun promised that it would be able to defeat the Tiger's front armour out to 1,000 yards, in actuality it wasn't even capable at 300m, much to the dismay of the US tank crews.

Now let me see just ONE single photo of a 76.2mm Zis gun having penetrated the front armour of the Tiger - you'll have a hard time finding one!

Soren
you wrote "Against WW2 AP projectiles the best armor BHR was 255 - 265 BHN, the level of the Tiger Ausf.E's armor, the same armor which managed to stop 76mm 77mm Allied AP projectiles at point blank range!", so I took that included also side armour. All photos showing soviet 76,2mm penetrations I recall showed holed side armour of Tiger and usually there are a group of hits close to each other of which only one is a clean penetration. So clearly Soviet 76,2mm gun was hard pressed to penetrate Tiger's 82mm side armour. I only wanted to notice you that you made too sweeping claim. After all it's probably that the commonest reason to Tiger loss was hit/hits by 76,2mm AP round(s). Also in your message there wasn't a mention on APDS.
But I think we a not so far each other when we are talking on Tiger I, a very good but expensive AFV.

Juha

Juha said:

Soren
you wrote "Against WW2 AP projectiles the best armor BHR was 255 - 265 BHN, the level of the Tiger Ausf.E's armor, the same armor which managed to stop 76mm 77mm Allied AP projectiles at point blank range!", so I took that included also side armour. All photos showing soviet 76,2mm penetrations I recall showed holed side armour of Tiger and usually there are a group of hits close to each other of which only one is a clean penetration. So clearly Soviet 76,2mm gun was hard pressed to penetrate Tiger's 82mm side armour. I only wanted to notice you that you made too sweeping claim. After all it's probably that the commonest reason to Tiger loss was hit/hits by 76,2mm AP round(s). Also in your message there wasn't a mention on APDS.
But I think we a not so far each other when we are talking on Tiger I, a very good but expensive AFV.

Juha

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Soviet 76.2mm BR-350B projectile can penetrate Tiger side 82mm amor within 100-200 meters (Kursk battle), that's suicide range. With reagrd to more powerful BR-350P projectile, its service was after Kursk battle.

Soren said:

No Glen, the thicker plates were NOT of worse quality! The BHN level was just lower, which is completely normal. QUALITY DID NOT CHANGE.

Against WW2 AP projectiles the best armor BHR was 255 - 265 BHN, the level of the Tiger Ausf.E's armor, the same armor which managed to stop 76mm 77mm Allied AP projectiles at point blank range! Yet the 88mm KwK43 L/71 is capable of punching holes in this armor beyond 4 km if the thickness is 100mm! The KwK43 would punch through 100mm of 300 + BHN armor past 4km for crying out loud! The 122mm D-25T can hardly punch through 100mm of VERTICAL 240 BHN armor at 3km, the 88mm KwK36 L/56 being just ~10mm behind it.

And like Delcyros explains De marre's theory DOES NOT WORK for these projectiles! It works for solid shot AP projectiles, NOT APCBC, esp. not when slope is applied! The theory is from 1870 Glen! Not 60 years later when the APCBC projectile was introduced!

Also for the last time, the 88mm KwK43's APCBC projectile was designated Pzgr.39/43, NOT Pzgr.39-1, the 88mm KwK36's APCBC projectile was designated Pzgr.39-1!

Its time you get this into your head Glen, cause its getting really straining having to repeat it!

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I've shown you the picture in which the Pzgr.39-1 and Pzgr.39 share SAME penetration ability. Kwk43 can also fire Pzgr.39-1 shell.

In spite of what type the projectile is, penetration is NOT directly proportional to KE (per square). The Data has proved this.

Even the Tiger Ausf.E infact remained superior in combat to any Soviet tank till the end of the war.

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JS2 late version(from 44 mid) is much superior to Tiger Ausf.E. Its 120mm/60 degree upper glacis amor is immune to any German tank gun and its 160mm turret front amor can only be penetrated by kwk43's APCR within 800 meters. That's to say, Tiger Ausf.E can NOT penetrate Js2 late front amor at point blank range in spite of what type shell used(APCBC, APCR). Lower glacis amor of any tank is easily to penetrate and seldom to hit, so ignore it.

Believe it or not.

All things beeing equal, doubling the velocity will not quadrupel the penetration. It´s actually short of this, in between (roughly) ^1.4 and ^1.7, depending on the projectile in question (the projectile determines specific penetration).

Russian armour usually was very hard (400+ BHN) but typically of very low tensile strength and limited ductility with accompanied manufacturing related deficiancies. Laminations and bubbles were recorded very often in them. Basically, the russians were producing overhard cast plates, which were not as good as high quality plates of lower BHN levels but occassionally very tough and much easier to produce. They would have been superior if they would have been of entirely good quality with regards to tensile strength and ductility. But there was no technology existing to produce 100mm +, 400 BHN plates with these properties. These deficiancies make penetration tests very chancy for the soviets.

A high velocity, 75mm projectile, impacting an JS-II may not make it through but will throw off enough armour material from the backside of the RAS plate to deliver fatal damage inside on their way. These high velocity "discs" are a serious thread, typical for overhard plates. Another problem with overhard plates is that the projectile, if engaging the armour at high obliquity, may stretch the plate (and in this regard low tensile strength is negative) to it´s limits, if the projectile start enough sideway movement of the plate to "overstretch", the plate will shatter.
On the other hand, very high velocity projectiles impacting are moving close to the speed, where the filler explodes (if enough deceleration is induced). That´s why just giving more striking velocity will not always asset penetration. Then You will have to move to a larger (=heavier) projectile. The proposed 75mm L100 falls into this category.

Glen
I know, IMHO many of the photos were taken to show that it could be done and to show an extraordinally deed. In war one must try to cope with equipment at hand even if that meant rather suicidical tactics. IMHO with closely grouped multiple hits the penetration was possible to achieve a bit farer away. IIRC Soviet tactic was to open fire with all 4 guns of an AT battery against a single Tiger. Only after/if the first Tiger was neutralized the fire was shifted against another target.

Juha

"JS2 late version(from 44 mid) is much superior to Tiger Ausf.E. Its 120mm/60 degree upper glacis amor is immune to any German tank gun and its 160mm turret front amor can only be penetrated by kwk43's APCR within 800 meters. That's to say, Tiger Ausf.E can NOT penetrate Js2 late front amor at point blank range in spite of what type shell used(APCBC, APCR). Lower glacis amor of any tank is easily to penetrate and seldom to hit, so ignore it.

Believe it or not."

I don't believe it. Read Soviet combat reports, the IS-2M was being knocked out by Panthers and Tigers at ranges up to and including 1,000 metres and it's D-25T could only penertrate the Panthers armour up to and including 600 metres.

The IS-2M suffered from poor armour quality and the crews suffered as a result. The Soviet industry considered tempering the IS-2M armour too expensive and time consuming so the problem remained until wars end. The numbers look good when studying the IS-2Ms armour, it was designed to be immune to the Tiger at ranges up to 1,000 yards - but it wasn't and that's a fact.

delcyros said:

All things beeing equal, doubling the velocity will not quadrupel the penetration. It´s actually short of this, in between (roughly) ^1.4 and ^1.7, depending on the projectile in question (the projectile determines specific penetration).

Russian armour usually was very hard (400+ BHN) but typically of very low tensile strength and limited ductility with accompanied manufacturing related deficiancies. Laminations and bubbles were recorded very often in them. Basically, the russians were producing overhard cast plates, which were not as good as high quality plates of lower BHN levels but occassionally very tough and much easier to produce. They would have been superior if they would have been of entirely good quality with regards to tensile strength and ductility. But there was no technology existing to produce 100mm +, 400 BHN plates with these properties. These deficiancies make penetration tests very chancy for the soviets.

A high velocity, 75mm projectile, impacting an JS-II may not make it through but will throw off enough armour material from the backside of the RAS plate to deliver fatal damage inside on their way. These high velocity "discs" are a serious thread, typical for overhard plates. Another problem with overhard plates is that the projectile, if engaging the armour at high obliquity, may stretch the plate (and in this regard low tensile strength is negative) to it´s limits, if the projectile start enough sideway movement of the plate to "overstretch", the plate will shatter.
On the other hand, very high velocity projectiles impacting are moving close to the speed, where the filler explodes (if enough deceleration is induced). That´s why just giving more striking velocity will not always asset penetration. Then You will have to move to a larger (=heavier) projectile. `The proposed 75mm L100 falls into this category.

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Good post，I agree with you about "between ^1.4 and ^1.7" and the relationship beteen thickness and hardness/toughness.

<<TABLE OF METALLURGICAL PROPERTIES OF NAVAL ARMOR AND CONSTRUCTION MATERIALS© >>
by NATHAN OKUN (Revised 10 July 2002

GERMAN KRUPP "WOTAN STARRHEIT" (Wsh) ("Extra-Hard 'Wotan' Armor Steel")

Special extra-hard form of "Wotan" armor for use on the spherical anti-aircraft directors used by World War II German heavy warships and in similar lightly-protected areas. Similar in principal to the extremely hard British and American "Homogeneous Hard" aircraft armor of thicknesses up to 0.5" (1.27cm) used to protect fighter and bomber crews, but not as extreme due to its greater thickness. Manufacture was possible because thin metal plates can be hardened (and thus strengthened) to a high level while retaining enough toughness. Similar to tank armor, which is made of higher hardness to protect against close-range, high-velocity projectile impacts, which is also true here since aircraft strafing will be at close range and projectile fragments are moving at a high velocity near the point where their filler explodes. Very low Percent Elongation should result in larger scaling effects than with Wh.
AVERAGE QUALITY: 1.10 (when hit by projectiles up to 8", dropping off slowly and steadily when hit by projectiles above this size, but at a higher rate than with Wh)

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I completely support the words in red.

The official German penetration figures for the 8.8cm KwK36 KwK43 with the Std. Pzgr.39 APCBC projectile against 260 BHN RHA armor laid back 30 degree's from the vertical:

Range: KwK36 / KwK43
100m: 120mm / 202mm
500m: 110mm / 185mm
1,000m: 100mm / 165mm
1,500m: 91mm / 148mm
2,000m: 84mm / 132mm

These figures were consistantly achieved against 260 BHN RHA armor plates. Std. criteria demanded atleast 2/3's of the projectiles fired to completely penetrate the test plate, ie. a 100% clean penetration. This is the most strickt critera used by any country during WW2.

By comparison the US testing criteria for their own rounds demanded only that 50% of the projectiles fired to partially penetrate the test plate. Hence why the 7.5cm KwK42 L/70 was found to outperform the US 90mm M3 in the tests conducted at the Aberdeen proving grounds against 240 BHN RHA armor.

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WWII cannon penetration criterion

Germany

definition of penetration:
completely penetrate

probability of penetration：
50%

target plate：
type：RHA
thickness/hardness：
5-15mm/BHN 435-465
16-30mm/BHN 338-382
31-50mm/BHN 323-368
51-80mm/BHN 309-338
81-120mm/BHN 279-309
121-150mm/BHN 235-265
151-275mm/BHN206-235


BRITISH

before 1942

<20mm calibre，completely penetrate，probability:60%
target plates:RHA，thickness 3-30mm，BHN:440-475

2 pdr cannon，20% body of projectile penetrate，probability:80%
25 pdr cannon，completely penetrate ，probability 50%
target plates:RHA，thickness>15mm，BHN 300-331

1942-1945
all cannon，completely penetrate，probability:50%
thickness/hardness
3-14mm/ BHN 340-388
15-80mm/BHN 262-321
85-120mm/BHN 255-302
125-160mm/BHN 241-285
>160mm /BHN ?


American
definition of penetration:
certain part of projectile penetrate

probability：50%

target plates：RHA
6-13mm/BHN 330-370
25mm/BHN 240-350
38mm、51mm、63mm/BHN 240
76-127mm/BHN 220-240
>127mm/BHN 220


Rassia
completely penetrate，probability:80%

target plates：RHA
hardness: BHN 250-380

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We can see the hardness IS relative to thickness. Good amor is the excellent combination of HARDNESS and TOUGHNESS while these two factors are usually oppose each other.

(toughness relative to the tensile and yield strengths of the material)

Glen, the De-Marre formula assumes solid AP-shots without cap for a very narrow range of T/D ratios and obliquities. Outside this envelope, the De-Marre formula shows results which some times work, sometimes don´t work, just like a monte carlo alike probability step system. You don´t want this condition to apply for Your question.

I fully agree in plate thickness and quality related issues. However, it could defeat 200mm plates. It´s true that 200mm are not "true" 200mm in stopping power but the 200mm it could defeat where usually of the same quality as those encountered in the battlefield. So the difference is of more theoretical interest, as it shows marked problems in calculations when applying the De-Marre formula. Never use it at T/D ratios above 1.0, differences may be fractions, but fractions are important.

When calibrating on 2420 fps striking velocity at 100m and 30 deg for the KWK 36, and assuming the projectile is with regards of it´s properties like a stand. US M79 AP, without cap and filler, the critical plate thickness at which it achieves full penetration is 4.7" at a relative quality of 1.25.
Comparing to a striking velocity of 3140 fps for the L71, I get a penetration of 7.2" single plate aequivalent of quality= 1.25 or 7.88" single plate aequivalent perforation of quality = 1.14.
BHN value for quality 1.25 = 280, matching requirements for 120mm plates
BHN value for quality 1.14 = 255, matching requirements for 200mm plates

Calculations performed with M79APCLC

best regards,
delca

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I agree with you. One exmaple: 122mm D25T/AP sharp-tip projectile:BR-471

Soviet penetration table

completely penetrate，probability:80%

0M 500M 1000M 1500M 2000M
**** 122mm 115mm 107mm 97mm (α=30 degree)

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D25T/AP is solid AP-shots without cap, OK for De Marre formular; 30 degree obliquity, OK, T/D is below 1.0,Ok. De Marre's result:
**** 153mm 143mm 132mm 119mm (vertical)
acutal score
**** 152mm 142mm 133mm 122mm (vertical)

Very accurate!

However, I don't know whether the De Marre formular can be applied to 55 degree plates. According to Russian test, D25T/AP can penetrate Panther D's 85(80)mm/55 degree upper glacis @650m away. This fact is acceptable for all of us, isn't it?

The Russian Battlefield - JS tanks: development history

Further, after the first encounters between the JS-2 and German heavy tanks, it turned out that the sharp-nosed 122 mm APHE round - the BR-471 - could only penetrate the frontal armour of a Panther up to 600-700 metres

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For 122mm solid AP-shots without cap(sharp tip), 85mm/55 degree is equalient to 179mm vertical (De Marre's result) BTW, 80mm/55=166mm
85(80)mm/55degree plate has the same weight as 148(140)mm vertical amor, therefore if PantherD's glacis is NOT obvious bigger than 148(140)mm,those Panther's designers will be idiots!

@650 meters, D25T/AP(HE) can penetrate 149mm soviet target plates whlie it can finish 150-166/179mm german amor......

With regard to amor quality, Panther D>A>G (D version is about 20mm better than G version)and D25T/AP vertical penetration @0m is only 13mm bigger than @650m. Now someone is in a dilemma: If the Panther@650m is G version , Js2 AP projectile can NOT penetrate Panther D at point blank range! Who will believe that? If the Panther@650m is A version, at least, A/G's amor quality is inferior to soviet target plates, my opinion is D version.

If you don't believe German amor is inferior to soviet target plates, let's check the performance of kwk43/APCBC shooting Panther D: 650m! same as D25T/AP.

Apparently,kwk43's APCBC has a much better penetration than D25T/AP, however, that's NOT the truth. Two reasons:

1) APCBC has a normalization effect which makes its 30 degree penetration is very close to its vertical score, therefore, 202/cos(30)=233mm is quite above kwk43's piont blank range ability.

2) Poor quality of thick target plates has given us the fake penetration of kwk43, 17pdr ....

Delcyros said

I fully agree in plate thickness and quality related issues. However, it could defeat 200mm plates. It´s true that 200mm are not "true" 200mm in stopping power but the 200mm it could defeat where usually of the same quality as those encountered in the battlefield. So the difference is of more theoretical interest,

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I agree with you partially,Delcyros. If rassian produce 200mm vertical amor which is of worse quality than their thiner ones, kwk43's apcbc can penetrate it @100m. However, if they put up 100mm/60 degree which is equal to "true" 200mm+, kwk43's apcbc can NOT penetrate it, I am sure! That's why tank designers love sloped amor; that's why Panther D's upper glacis is stoutness when facing kwk43's apcbc, including 17 pdr's APCR shell which also has >150mm penetration score.

Furthermore, the APCR shell is also insufficient in shooting Panther's upper glacis because APCR's real caliber is between 40mm and 50mm. That's to say. APCR's T/D ratio is too high and the advanage of APCR's vertical score will be counteracted by the increase of equivalent vertical stopping power. For example, 50mm solid AP-shots without cap(sharp tip), projectile on 85mm/55 degree=260mm vertical, much bigger than 179mm of D25T/AP.

Kwk43's vertical penetration is 10mm more than D25T at point blank range, and it's advantage is decreasing when the range is longer. At the range of 600-700m, they have same vertical penetration where they can both penetrate Penther D's glacis. It's coincidence: kwk43's has better projectile(apcbc vs ap) and D25T has better caliber(122mm vs 88mm).

Beyond 1000m, D25T has gained the advantage of vertical penetration due to its heavier body=good in retaining velovity.

When soviet APBC shell (BR-471B)is introduced, D25T is obvious better than kwk43's APCBC/APCR when shooting 85mm/55degree. D25T/APBC (D10T)can destroy Panther D beyond 1000m, this is very important for russian, and this achievement is impossible for allied tank gun, only German 128mm could compete with russian. Kwk43? that vaunting gun? impossible! Panther G glacis can be penetrated by APBC(BR471B) beyond 2500m!

Above is about medium-thickness/high obliquity plate(such as Panther), however, for thin/high obliquity plate(such as T34),the situation is different. APCR's carliber is close to 47mm(T34), so German APCR's 60-obliquity penetration is better than their own APCBC within certain distant. For example, kwk36's APCR can destroy T34 more far away than it's apcbc. Nevertheless, the advantage of kwk43's APCR compared to APCBC is meaningless: APCBC can destroy T34/85 beyond 2000m where the APCR shell's velocity has been consumed a lot and has no advantage.

With regard to larger caliber D10T/D25T, their AP shell ability facing thin/high obliquity plate is equal to kwk43's APCBC/APCR, If APBC is concerned, soviet gun is better: Js2 can destroy T34/85 beyond 3km!

overall, the penetration of D25T/D10T is eqaul to kwk43(if not slightly better), btw, I believe D10T is inferior to D25T in WWII. Of course, I am not talking about the fire rate, accutare and so on.

plan_D said:

"JS2 late version(from 44 mid) is much superior to Tiger Ausf.E. Its 120mm/60 degree upper glacis amor is immune to any German tank gun and its 160mm turret front amor can only be penetrated by kwk43's APCR within 800 meters. That's to say, Tiger Ausf.E can NOT penetrate Js2 late front amor at point blank range in spite of what type shell used(APCBC, APCR). Lower glacis amor of any tank is easily to penetrate and seldom to hit, so ignore it.

Believe it or not."

I don't believe it. Read Soviet combat reports, the IS-2M was being knocked out by Panthers and Tigers at ranges up to and including 1,000 metres and it's D-25T could only penertrate the Panthers armour up to and including 600 metres.

The IS-2M suffered from poor armour quality and the crews suffered as a result. The Soviet industry considered tempering the IS-2M armour too expensive and time consuming so the problem remained until wars end. The numbers look good when studying the IS-2Ms armour, it was designed to be immune to the Tiger at ranges up to 1,000 yards - but it wasn't and that's a fact.

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Give me the proof of the penetration on Js2 late version's upper glacis(120mm/60). You will find it hard to get that just like the proof of Kingtiger's(150mm/50).

The straight thickness of 120mm/60 is 240mm while the 150mm/50=233mm, 240mm>233mm,furthermore, Js2's amor is better due to its smaller thickness and the poor quality of kingtiger amor.

Look,these are Js2 LATE with "straight nose", don't mix up with Js2 EARLY which is far inferior.

The vast majority of pictures in this world are of IS-2m (Model 1944). The IS-2m was of a simpler build than the IS-2 not a vast improvement of armour quality. In fact, the major difference between the two was the replacement of the A-19 122mm with the D-25T 122mm. The only thing I can think of here is the replacement of the stepped-armour glacis plate on the IS-1.



IS-1

Kotin believed that this new armour protection could withstand the KwK36 at over 1,000 metres, whilst the A-19 could pierce 160mm at 1,000 metres. Up-armouring the turret was out of the question because of weight distribution.

The IS-2m ("late version" in your words, and not to be confused with the 1950s IS-2M) replaced the A-19 with the D-25T because of its more efficient breech. Unfortunately for Soviet tank crews it was discovered in combat that the D-25T (nor the A-19) could penetrate the Panthers armour above 600 metres.

The IS-2 and IS-2m (Model 1944) both suffered from splintering of their armour, throughout. This was due to the complexity and cost of tempering their armour - the problem remained throughout the war.

I have no pictures at the moment, but I will kindly look. But I do have to leave you with the battle of Sandomierz, the most famous IS-2 battle against the Pz.Kpfw VI ausf B. The Soviet forces lost three IS-2s and seven damaged and in their post battle report they filed that their tanks were vulnerable up to 1000 metres because of faulty casting.

It'll be more difficult to find picture evidence, since the Germans mostly left the battlefield to the Russians in 1944 - and Soviet propaganda didn't like pictures of wrecked IS-2s albeit I know there are some.

Glen, you are still clueless about which you talk. You're a gamer, I had that figured out from the start.

First of all your criteria citings are completely wrong.

These are the true criterias used by each country:

German test criteria
2/3rds (66 %) of the projectiles fired must penetrate the plate completely, ei. 100% of the projectile.

British test cirteria
50% of the projectiles fired must completely penetrate the plate, ei. 100% of the projectile.

US test criteria
50% of the projectiles fired must partially penetrate the plate.

USSR test criteria
80% of the projectiles fired must partially penetrate the plate, atleast 80% of the projectile.


The Russianbattlefield website has to no surprise got these figures totally screwed ofcourse, amongst other things claiming German criteria was for 50% of the projectiles fired to penetrate, which is complete hogwash.

Now moving on Glen, you theory is that the 88mm KwK43 does not penetrate 202mm of the same armour at 100m as that used for testing the 88mm KwK36, and you therefore argue that this means that the KwK43 figures are overblown. This however is complete hogwash Glen, cause you see with increased armour thickness a lowering of the BHN is inevitable, and that goes for tanks as-well as test plates. BUT, also notice that at 2.5km the KwK43 manages to consistantly penetrate 127mm 300 + BHN armour plates, the same the KwK36 is just capable of at below 100m. So while it is true that if the 200mm plates were of the same BHN as the 120mm ones then the results would've been different at close range, however the bottom line is that the thicker plates were of 250 - 265 BHN while the thinner ones were at 295 - 307 BHN (And the same was true for all armour of that period, BHN dropped with increased thickness).

SO Glen, if we were to follow your flawed logic that the 17pdr 88mm KwK43's figures were overblown then so is the figures of the 122mm D-25T's, 100mm D-10's, 90mm M3's etc etc ... Fact is however that none are, they were just fired against thicker but lower BHN plates at close range by virtue of their increased power and at hard but thinner plates at longer ranges.

Ofcourse had to been a serious researcher on the subject you would've known the above.

Moving onwards...

NO glen, the KwK43 did NOT fire the Pzgr.39-1, it fired the the Pzgr.39/43. Or are you seriously trying to suggest that the Germans for some odd reason somehow just put Pzgr.39-1 projectiles in their KwK43 cartridges ??! No Glen, the KwK43/PaK43 had its own ammunition, the projectiles used was the Pzgr.39/43 which was different than the Pzgr.39-1 both in terms of heat treatment and exterior design. The drive bands on the Pzgr.39/43 were wider than those on the Pzgr.39-1 in order for them to withstand the much higher pressure created by the KwK43/PaK43 guns. And the exact same goes for the 75mm KwK42 which ALSO fired a different round than its less powerful littlebrother, the 75mm KwK40, and this round was as explained designated the Pzgr.39/42, and again the difference between the two was the heat treatment and exterior design.

Now you need to get the above into your skull, cause so far you have only demonstrated that you have absolutely no clue what you're talking about, neither about this nor that of the armour penetration subject.

Soren said:

Glen, you are still clueless about which you talk. You're a gamer, I had that figured out from the start.

First of all your criteria citings are completely wrong.

These are the true criterias used by each country:

German test criteria
2/3rds (66 %) of the projectiles fired must penetrate the plate completely, ei. 100% of the projectile.

British test cirteria
50% of the projectiles fired must completely penetrate the plate, ei. 100% of the projectile.

US test criteria
50% of the projectiles fired must partially penetrate the plate.

USSR test criteria
80% of the projectiles fired must partially penetrate the plate, atleast 80% of the projectile.

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Weather my criteria citings is wrong or not isn't important, my focus is that, BHN dropped with increased thickness. I even don't care about "hardness" itself, I care about "quality of amor" which is more than "hardness". It is probably that the thicker amor(>150-160mm) has inferior quality compared to thiner ones.

cause you see with increased armour thickness a lowering of the BHN is inevitable, and that goes for tanks as-well as test plates.

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For example, 120mm/60(250 BHN)is equivalent to 260mm(250 BHN) vertical when facing 88mm shell, however, nobody can produce a real 260mm(250 BHN) vertical amor, usually, they can only produce 260mm(200 BHN) etc.

also notice that at 2.5km the KwK43 manages to consistantly penetrate 127mm 300 + BHN armour plates, the same the KwK36 is just capable of at below 100m. So while it is true that if the 200mm plates were of the same BHN as the 120mm ones then the results would've been different at close range, however the bottom line is that the thicker plates were of 250 - 265 BHN while the thinner ones were at 295 - 307 BHN (And the same was true for all armour of that period, BHN dropped with increased thickness).

SO Glen, if we were to follow your flawed logic that the 17pdr 88mm KwK43's figures were overblown then so is the figures of the 122mm D-25T's, 100mm D-10's, 90mm M3's etc etc ... Fact is however that none are, they were just fired against thicker but lower BHN plates at close range by virtue of their increased power and at hard but thinner plates at longer ranges.

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No, D25T's score is almost below 150mm, and kwk43's is around 200mm，I believe the german 200mm target plates is probably inferior than soviet 150mm ones.

If you find a score of D25T is 180mm@*m，that's a fake score just like kwk43's.

At least, I've prooved the soviet D25T target plates are better than Panther glacis. Since you believe the kwk43 apcbc's 200mm+ is true, how can you explain it only penetrate panther glacis at range of 650m?

Kwk43's performance in battle field is not so strong. I'll collect more evidence,

plan_D said:

The vast majority of pictures in this world are of IS-2m (Model 1944). The IS-2m was of a simpler build than the IS-2 not a vast improvement of armour quality. In fact, the major difference between the two was the replacement of the A-19 122mm with the D-25T 122mm. The only thing I can think of here is the replacement of the stepped-armour glacis plate on the IS-1.



IS-1

Kotin believed that this new armour protection could withstand the KwK36 at over 1,000 metres, whilst the A-19 could pierce 160mm at 1,000 metres. Up-armouring the turret was out of the question because of weight distribution.

The IS-2m ("late version" in your words, and not to be confused with the 1950s IS-2M) replaced the A-19 with the D-25T because of its more efficient breech. Unfortunately for Soviet tank crews it was discovered in combat that the D-25T (nor the A-19) could penetrate the Panthers armour above 600 metres.

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kwk43 apcbc can only penetrate pantherD glacis within 650m, too.

I have no pictures at thre moment, but I will kindly look. But I do have to leave you with the battle of Sandomierz, the most famous IS-2 battle against the Pz.Kpfw VI ausf B. The Soviet forces lost three IS-2s and seven damaged and in their post battle report they filed that their tanks were vulnerable up to 1000 metres because of faulty casting.

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kwk36's APCR can pen. 122mm/30 degree @1500m, one section of js2 early's front amor is 120mm/30 degree.

For example,if Panther's galcis is equaivalent to 180mm vertical facing 88mm apcbc, its performance is quite better than a 180mm verical amor produced by german because panther's amor quality is quite better than the thick vertical plates. If kwk43's @1000m score on target plate(worse quality than 80mm plate)is 180mm vertical, it just can not pen. panther glacis @1000m! It must be within 1000m, such as 650m.

I'm not talking about test plates or the firing range, I'm talking about real life situations and the true quality of armour. The Soviets recognised that the theoretical ability of the IS-2m armour did not match reality, because in reality the IS-2m armour splintered and shattered when, in theory, it should have been invulnerable.

Most IS-2 models that saw combat were the IS-2 Model 1944 ("late version") with this slight improvement in armour over the IS-2 model. The faulty casting and the lack of tempering remained - if you wanted to test what really happened you would need a test plate of the same quality casting as the real-life IS-2m.