Allied tank armor, quality control

Discussions on the vehicles used by the Axis forces. Hosted by Christian Ankerstjerne
Yoozername
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Re: Allied tank armor, quality control

Post by Yoozername » 06 Apr 2019 02:21

Who states that the KWK40 didn´t use 75mm K.Gr.rot Pz. during 1942 (before the widespread service advent of the 75mm Pzgr.39), which in british terminology is a 75mm A.P.C.H.E.?
Can you state a source that they did? Given that it could not take the high velocities, why would the Germans do that? Why would they produce so much HEAT ammunition for the KWK 40 weapon and put out SOP on limiting the Pzgr 39 use?
Further, the only actual test data, I see here, were conducted with 6pdr and 2pdr. Other ordnance items are estimates.
Yes, we agree. See my post above.

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Re: Allied tank armor, quality control

Post by critical mass » 06 Apr 2019 18:13

75mm K.Gr.rot Pz. was to be fired from all StuK and KwK40. There is a specimen of it supposedly in the Panzermuseum Münster (Even though it does look to me like pzgr39, compare attachment) . There was a 75x 514 and a 75 x 495mm cartridge for the K.Gr.rot Pz.
As to why it was used- I suppose, they weren‘t fully aware of all the difficulties involved here at first in 1941/2. Presumably, thats why they felt the need to point out the differences in performance to the pzgr39 in the lilientahlreport 166 files from 1943. Against soft armor it should work to higher velocities. Against T34 HHA, scaling takes over anyways, which means the projectile will often break through despite projectile break up, albeit under waste of explosive action. Against the medium hard KV1 armor- and similar british IT80 plate, the projectile breaks up easily, though. The K.Gr. rot Pz. was capped (unlike the 5cm Pzgr Gg) and when they understood that the design was inefficient, the pzgr39 was selected to replace the SAPCBC. However, a large number of StuG and Pz4 lang were issued before the 75mm Pzgr39 was avaiable in quantity. This required stop gaps.

I ll need to check my sources but I vaguely remember that the first Pzgr39 were issued for PAK40.
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T. A. Gardner
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Re: Allied tank armor, quality control

Post by T. A. Gardner » 06 Apr 2019 22:15

The US certainly did remanufacture German antitank ammunition for their own use. Captured German stocks starting in N. Africa were used for the purpose.

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Re: Allied tank armor, quality control

Post by Yoozername » 07 Apr 2019 05:28

CM, if you have a source, besides a museum display, I would be very interested in seeing it.

http://panzer-elmito.org/panzertruppe/t ... 42__D.html

Notification by Generalmajor Gustav Harteneck (2.AOK) to his subordinates dated 17.6.1942 warning of the extreme shortage of ammunition in front for anti-tank guns (7.5 cm Pak40) as well as for tank guns (7.5 cm KwK40).
The level of production allows, currently and temporarily, only a very small supply of ammunition for the new heavy anti-tank guns as well as tank guns. In the coming months, and only in the best of cases, will be able to supply these weapons with basic equipment, in most cases even less.

The Führer, aware of this situation, has ordered and thus the delivery to the troop of these weapons. Even with basic ammunition equipment, these weapons are called to play a fundamental role in the fight against Russian heavy tanks.

The troop must be made to understand this directive. Every troop leader, as well as any battery chief, must understand that from now on, the condition for heavy antitank weapons to play a decisive role, is that they will only be used against heavy Russian tanks and only in those cases where that at short distances can not be fought with 5 cm anti-tank guns. That is, they will only be used to attack the front of the T-34, KW I and II; these vehicles can be destroyed by their sides with the anti-tank gun of 5 cm.

Skillful positioning as well as the camouflage of heavy anti-tank guns is of great importance. To improve the performance of the barrel and in relation to its position, we must try to approch natural barriers in the terrain that hinder the tank. Likewise, Panzer IV vehicles as well as assault guns equipped with the KwK 40 cannon must adapt to the shortage of ammunition. We must also take into account that in the coming times the Panzer III and the Panzer IV with long cannon and the Sturmgeschütz 40 will have a very small number of fragmentary ammunition of high explosive ( Sprenggranaten ).

At present, the heavy anti-tank guns and the aforementioned tanks and assault guns can be equipped, depending on the model, with ammunition equipment of between 70 and 150 projectiles per cannon; of them between 30 and 50 will be perforating point projectiles ( Panzergranaten ). This basic kit will be complemented slowly and progressively. It is prohibited to make requests for ammunition repeatedly.

All communication in reference to this topic at the higher level of division will only occur orally; This order once read must be destroyed.

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Re: Allied tank armor, quality control

Post by peeved » 07 Apr 2019 06:49

One Yoozernamemember posted the following translation of a Soviet report at http://www.matrixgames.com/Forums/print ... ?m=2800982
Ref. ¹ 632/3
11/IX-44 y.

Report of spec.lab. NKV ¹ 101-1 on theme:
Examination of hitting features of T-34 tank fuel tanks with armor-piercing/high-explosive and cumulative (armor-burning){HEAT} shells of german fascist army.
Resp. executors: Rozov, Kaminsky, Shchurov
Superviser: Sarafanov

1. History of question
In the battles of spring-summer 1943 tank army, tank corps and tank brigades commanders begin to note that cases of T-34 tanks combat losses with catastrophic explosions of fuel tanks or fire in engine compartment became more frequent. For instance, cases of burn T-34 tanks in battles of summer 1943 near Kursk exceeded those of T-70 tanks by 4-9%...
By order of chief of BTU GBTU of Red Army engeneer-colonel Afonin, 11 Sept. 1943 a comission was formed to study this problem.
Our group studied possibilities of T-34 fuel tank explosion with various armor-piercing tools and valuation of its probable impact on crew and inner equipment.

2. Target setting
Comission's survey of 72 destroyed during Kursk battle tanks on SPAM {field repair} bases have shown that most of them (68%) were destroyed by fire originated in result of fuel tank depressurization with subconcious inflammation of diesel fuel.
All mentiond tanks have breach in hull side or underskirt by AP, armor-burning shells or field charge.
About 1/3 abovementioned tanks lack one or two front fuel tanks and have demolition inside or partial, or even complete destruction of hull's welded seams, caused by internal explosion.
Only little part (8%) of tanks have signs of inner explosion with singns of flames, whereas 24% of machines were destroyed with explosion without any signs of iner flames. Often even ordinance was completely unharmed in chest. According given order our group researched this particular type of destruction - fuel tank explosion.
Members of comission engeneer-colonel Gurov and MVTU associate professor Krutov assumed after inspection of exploded tanks that given damage was caused by explosion of front fuel tanks placed inside crew compartment of T-34 after impact of some specific german ammunition.
Engeneer-major Firsov expressed opinion that such explosion could happen in result of burst of high temperature ammunition based on thermite or electron {aluminium or alloy powder and mixed with rust}
Group of com. Sarafanov recieved a task personally from chief of GBTU to explore the possibility of T-34 fuel tanks detonation after hit by various types of armor-piercing ammunition of german fascist army
{part missing}

4. Study equipment.
To verify assumtions of coms. Gurov, Firsov and Krutov, three sections layouts of 35 mm thick armoured steel with 135 l. {35 gallons} fuel tank established inside were built by NII-48 and Uralmashzavod. Also according to cover letter ¹ 312-a from 21.IV-44 y. a T-34 hull with turret and equipment but without weapons was put to testing ground by BTU.
{part missing again}

5. Experimenting on location.
First shelling of layouts was on 12/XII-43y. from ballistic cannon m.40 from 30 meters distance.
1. During the test fuel tank was full of diesel fuel, recieved by cover letter of com. Afonin from 5/XII. Total spent 8 m.38 shells, 5 m.39/40 shells and 5 armor-burning shells. The results are the following:
During tests fuel tank was completely destroyed 3 times, diesel fuel was flamed 4 times. Explosions were not recorded.
When the fuel tank was hit by fragments of m39/40 shell they were abruptly dragged. Many of fragments did not break through.
Conclusions: 100% filled fuel tank of T-34 tank cannot be a source to inner explosion of T-34 tank, but even serves a protection from fragments of armor and cores of m.39/40 shells. {Guess it's the exact meaning of these fuel tanks}
2. Since com. Krutov expected that petrol cannot explode either if tank is full, with com. Fedin sanction a tank of petrol was installed into section. 3 shots was fired with m.38 shell and one armor-burning. Explosions were not recorded, in 2 tests petrol flamed.

Second stage of trials was began 9/II-44y. For trials the same weapons were used with addition of 88mm recoilless cannon m.1943, firing 88mm armour-burning mines.
According to trials program partially filled tanks were tested. Prior to the test shootings the tank was carried on a truck for 1-2 hours on service roads on testing area. After that fuel was poured off according to test conditions and tank was being installed on layout.

4th series of shooting. Tanks filled to 10-25%. Tank exploding from hit of coherent jet being filled to 25% or less. Equivalent bursting power was near 30-50 gramms of trotyl. The hatch cover on roof of layout made to lift off the tanks was smashed out. In case of filling with petrol explosiveness reducing on avearge 1.5 times comparing to diesel fuel. Fuel tank detonation caused hatch cover to open. Welded seams of layout remained intact.
Another picture is observed when inside almost empty tank a high explosive part of 75mm armor-piercing shell with red ring (80 gramms of trotyl with detonator of 20 gramms of phlegmatized tan{I don't know how to translate it, it seems to be acronym. Pretty sure some one of military or defence professionals would recognize it, but I' not} in aluminium cup) is bursting. In this case exploding effect of the shell is heavily (several times) increasing. Welded seams of underskirt was destroyed by explosion, after that shock wave ripped underskirt offand partly destroyed the roof of layout. Layout admitted off.

6. Conclusions:
The best ratio for detonation of T-34 fuel tank is when it's 10-15% full and AP shell m.38 bursting inside. Burst causes immediate detonation fuel's vapour which adds to shell's explosion, mmultiplying it by 2-4, which corresponds with effect of 105-122mm AP shell.
Even better summary effect is reached when domestic 76.2mm AP shell ÁÐ-350À which contains 150 grmms of trotyl bursts. Summary effect corresponds with 152mm AP shell ÁÐ-540Á type, which contains 400 gramms of trotyl.
With reducing caliber of AP shell probability of fuel tank explosion decreases dramatically. 37mm and 45mm AP shell cause almost non existing detonation. It should be noted that further increasing of AP caliber do not lead to significant increase explosive power of ammunition bursting inside the fuel tank. The presence of 75-85mm containing 50-100 gramms of trotyl or less amount of morre powerful blasting substances (for instance, 30-80 gramms of A-1X-2 mixture or 25-50 gramms of phligmatized gexogen) is optimal, The capacity of fuel tank should not be less than 100 litres. 30-50 litres do not make significant increasing of AP ammunition blasting power.

Countermeasures:
1. Do not allow placing of fuel tanks in crew compartment
2. During action spend the fuel from rear tanks first as their hit is less probable
3. Try to lessen accumulation of fuel vapour and formation fuel vapour of high concentration inside tank with constructing measures.
4. Lessen volume of fuel tanks inside crew compartment at least twice.
5. Place fuel tanks behind armoured leaktight wall

Rozanov {such as in document}
Kaminsky
Shchurov
Chief of the group Sarafanov
"ballistic cannon m.40" used to shoot "m.38 [AP] shells", m.39/40 [AP] shells and armor-burning [HEAT] shells.
"Another picture is observed when inside almost empty tank a high explosive part of 75mm armor-piercing shell with red ring (80 gramms of trotyl [Sounds a lot like 7,5 cm Pzgr.rot] with detonator of 20 gramms of phlegmatized tan...in aluminium cup) is bursting. In this case exploding effect of the shell is heavily (several times) increasing. Welded seams of underskirt was destroyed by explosion, after that shock wave ripped underskirt offand partly destroyed the roof of layout. Layout admitted off. "
"The best ratio for detonation of T-34 fuel tank is when it's 10-15% full and AP shell m.38 bursting inside."

Markus

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Re: Allied tank armor, quality control

Post by Yoozername » 07 Apr 2019 15:06

Another thread. The cannon is being used as a test bed. In other words, they are testing the T34's fuel tanks, using the cannon to put various projectiles into it. Not testing actual production ammunition per se. But, it is an interesting discussion. Full tanks are safer than low fuel tanks, sort of the opposite of ammunition... It does mention that diesel tanks, when compared to petrol (gas), actually blow with more force.

http://www.matrixgames.com/FORUMS/tm.as ... =&#3383057

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Re: Allied tank armor, quality control

Post by Yoozername » 07 Apr 2019 16:47

I don't think there is any evidence the Pak 40 ever used anything but Pzgr 39, Pzgr 40 (very rare), Pzgr 38 HL/B up till December 1942. This actually shows the usage numbers. Note the number of HL/B being used along with Spgr.

http://www.matrixgames.com/forums/upfil ... AB7269.jpg
pak40.jpg
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Re: Allied tank armor, quality control

Post by Yoozername » 07 Apr 2019 17:06



Who states that the KWK40 didn´t use 75mm K.Gr.rot Pz. during 1942 (before the widespread service advent of the 75mm Pzgr.39), which in british terminology is a 75mm A.P.C.H.E.?
Notice, that Pzgr.39 is generally referred to by the small filler desgnation "75mm A.P.C.B.C. (small filler or small capacity)" once the difference between it and the older type of ammunition became known. The 75mm A.P.C.H.E. refers to a large filler or capcity. No distinction in projectile designations may refer to either the 75mm K.Gr.rot Pz. directly, or alternatively to a period when the difference between 75mm K.Gr.rot Pz. and 75mm Pzgr.39 was yet unknown.
Further, the only actual test data, I see here, were conducted with 6pdr and 2pdr. Other ordnance items are estimates.
Not sure this agrees with your terminology....

British Ordnance Board penetration graphs from 1943 and 1944.

O.B./43/CV.12 May 25,1943
shows for 2400 f/s muzzle velocity (731.52 m/s) of 14.81 lb. APCBC shell ("MV as tested by trial in KwK 40") at 0 and 30 degrees deflection:
2400 f/s penetration 121/102 mm,
2000 f/s (609.6 m/s) 98/83 mm,
1600 f/s (487.68 m/s) 75/63 mm.

O.B./43/CV.13 same date.
MV 1350 f/s (411.48 m/s) same shell model:
1300 f/s (396.24 m/s) 58/48.5 mm,
1000 f/s (304.6 m/s) 41.8/34.8 mm.

O.B./43/CV.20 for 15 lb. large HE cavity APCBC
1300 f/s MV December 14,1943:
1300 f/s 50.3/46.25 mm,
1000 f/s 35/32.94 mm.

O.B./44/CV.50 for 15 lb. small HE cavity APCBC December 13,1944 of Kwk 42
MV 3068 f/s (935.13 m/s),
Pak 40 MV 2600 f/s (792.48 m/s),
KwK 40 MV 2300 f/s (701.04 m/s):
3000 f/s (914.4 m/s) 182/156 mm,
2400 f/s (731.52 m/s) 133/104.5 mm,
2000 f/s (609.6 m/s) 104/77.5 mm,
1600 f/s (487.68 m/s) 75.5/55.5 mm.

(I suspect the clover leaf diagram is based on the O.B./43/CV.12 May 25,1943
shows for 2400 f/s muzzle velocity (731.52 m/s) )

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Mobius
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Re: Allied tank armor, quality control

Post by Mobius » 07 Apr 2019 19:54

Yoozername wrote:
07 Apr 2019 16:47
I don't think there is any evidence the Pak 40 ever used anything but Pzgr 39, Pzgr 40 (very rare), Pzgr 38 HL/B up till December 1942. This actually shows the usage numbers. Note the number of HL/B being used along with Spgr.

http://www.matrixgames.com/forums/upfil ... AB7269.jpg

pak40.jpg
Weren't the AP shells 6.8 kg.?

I'm not sure what the Gr. 38 rot is.
3/1942 is long after the Gr. 38 hl/A was introduced.
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Re: Allied tank armor, quality control

Post by critical mass » 08 Apr 2019 08:58

Yoozername wrote:
07 Apr 2019 16:47
I don't think there is any evidence the Pak 40 ever used anything but Pzgr 39, Pzgr 40 (very rare), Pzgr 38 HL/B up till December 1942. This actually shows the usage numbers. Note the number of HL/B being used along with Spgr.

http://www.matrixgames.com/forums/upfil ... AB7269.jpg

pak40.jpg
Not the L/46 Pak40, I stated KwK40 and StuK. And I presume the early L/41 & L/43 models are what You have to look for, because when the L/48 arrived, the K.Gr.rot has been replaced entirely by pzgr39.

Yes, both 75mm projectiles had the same weight: 6.8kg.

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Re: Allied tank armor, quality control

Post by critical mass » 08 Apr 2019 09:09

Yoozername wrote:
07 Apr 2019 15:06
Another thread. The cannon is being used as a test bed. In other words, they are testing the T34's fuel tanks, using the cannon to put various projectiles into it. Not testing actual production ammunition per se. But, it is an interesting discussion. Full tanks are safer than low fuel tanks, sort of the opposite of ammunition... It does mention that diesel tanks, when compared to petrol (gas), actually blow with more force.

http://www.matrixgames.com/FORUMS/tm.as ... =&#3383057
The 75mm was Patronenmunition. I doubt the interpretation that the soviets took a Patrone, removed the K.Gr.rot from it and attached it to a different cartridge is a correct one in view of absence of any indication for this deviation from default practice . It is more likely that they just followed default practice, that is they fired whatever captured material they had at their disposal to study how their t34 is affected by enemy ordenance.

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Re: Allied tank armor, quality control

Post by Yoozername » 08 Apr 2019 12:54

75mm K.Gr.rot Pz. was to be fired from all StuK and KwK40.
So, to be clear, you are saying that the high velocity weapons, that is the KWK 40 (L43 initially) and StuK 40 (L43), which were designed at the same time as the Pak 40, were to use a different armor piercing projectile design? That is, The Pak 40 would use the Pzgr 39, and the KWK/StuK weapons were to use the same projectile as the earlier KWK 37/StuK 37? You are not speculating that the Germans, who clearly had issues manufacturing the Pzgr 39 in the quantities needed in 1942, might have tried a 'substitute standard, such as using the earlier large capacity AP as a temporaneous solution; You are actually stating they designed the KWK 40/StuK 40 to fire it? How can you explain the report from summer of 1942 that I posted? The Germans are clearly issuing SOP as far as how/when to fire the armor piercing ammunition. They haven't fielded great numbers of Panzer IV F2 (G) or StuG III F at this time. It is actually quite low.
And I presume the early L/41...
This weapon design was dropped once the Germans started encountering the Soviet armor. The Germans did so because they knew they needed a higher velocity 7,5 cm class weapon. The initial German nominal velocity for the KWK 40/StuK 40 firing the PzGr was 740 M/s.

The Soviet test, which clearly states the range being 30 meters, also states a date, and this test was prompted by experience at Kursk. They clearly state using a 'cannon 40'
First shelling of layouts was on 12/XII-43y. from ballistic cannon m.40 from 30 meters distance.
So, these tests take place later in 1943, and the 'cannon 40' is what? A Pak 40? Kwk 40?
I doubt the interpretation that the soviets took a Patrone, removed the K.Gr.rot from it and attached it to a different cartridge is a correct one in view of absence of any indication for this deviation from default practice . It is more likely that they just followed default practice, that is they fired whatever captured material they had at their disposal to study how their t34 is affected by enemy ordenance.
So, what is your interpretation of the projectiles they fired? A mix of earlier ammunition mixed in with later ammunition? "m.38 [AP] shells", m.39/40 [AP] shells and armor-burning [HEAT] shells.

My own interpretation is that the 'm39/40' is actually a Pzgr 40 (tungsten carbide) round.
When the fuel tank was hit by fragments of m39/40 shell they were abruptly dragged. Many of fragments did not break through.
Last edited by Yoozername on 08 Apr 2019 13:15, edited 4 times in total.

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Re: Allied tank armor, quality control

Post by Yoozername » 08 Apr 2019 12:57

Weren't the AP shells 6.8 kg.?
I believe so, need to find the 'Ringbuch' data.

That data seems familiar. Is it from North Africa? Firing on British tanks? March 1942? I don't think they would have Panzer IV F2 then?

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Re: Allied tank armor, quality control

Post by Yoozername » 08 Apr 2019 14:16

Dated Jun 43...shows 6.8 Kg
ringbuch.jpg
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Re: Allied tank armor, quality control

Post by Yoozername » 08 Apr 2019 14:53

643.jpg
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