USA and DDR penetration about D25T gun

[TempestMKV]

Very interesting difference between these two resources.

USA data from test on aberdeen.
DDR data from archives.

It is obvious that the ballistic coefficiency (BC) of D25T AP shell (BR471) is lower than that of APBC shell(BR471B).
Both USA and DDR resource have proved this, however, the DDR data tells us that AP and APBC shell's penetration are almost the same at 100 meters (160mm v 158mm,ratio is 101.3%) while USA data demostrates APBC has more penetration at 100meters(206mm v 192mm,ratio is 107.3%).

What's the problem?

 

[Soren]

EDIT.

I notice that the docs you provided list penetration values as against vertical armour. Interesting.

The difference probably stems from the harder armour the Germans were using for the tests, 250 BHN vs 240 BHN RHA plates.

 

[Soren]

But as can be seen the 122mm D25T wasn't a very good AT gun, its' performance was close to that of the 75mm KwK42 L/70 on the Panther while being much heavier and much much slower to reload. In short the D25T was more of an anti personnel weapon than an anti tank weapon.

The Soviets should've concentrated more on their 100mm D-10 AT gun, which was an able design in the AT role, featuring better performance than the 122mm D25T while being lighter and faster to reload.

 

[Glider]

I admit that I am not suprised, after all the 122mm D25 was a modified version of the 122mm A19 field gun, whilst the 75L70 was designed for the AT role.
To say that it wasn't a good AT gun when it was roughly equal to the 75L70 is a little harsh, as the L70 was an excellent AT gun.

Many a British or American tanker would have settled for the 'poor' performance of the 122mm over the 75mm or 57mm.

 

[Soren]

Glider, keep in mind that it is only the 122mm D25T's penetrative performance which is equal to that of the 75mm KwK42, in terms of accuracy, reload rate overall weight the KwK42 is far superior, and all three aspects are what make a good AT gun.

In short the 122mm wasn't a good AT gun, it was infact pretty miserable, cause although it did pack a punch you had to make absolutely sure to hit with your first round as the reload time was extremely slow, which alone was hard enough with the poor optics in Soviet tanks.

 

[Glider]

I am aware of that but maintain that the British and US Tankers would happily swap a poor 122 with a chance of knocking out the larger German tanks, than a 75 or 57 with no chance.

 

[TempestMKV]

EDIT.

I notice that the docs you provided list penetration values as against vertical armour. Interesting.

The difference probably stems from the harder armour the Germans were using for the tests, 250 BHN vs 240 BHN RHA plates.

This is russian resource of APBC shell. Note that penetration comparation between 100m vs 2000m is 212mm: 152mm,ratio is 139%,while DDR corresponding ratio is 136%( APBC,160mm:118mm) ,but USA test's ratio is 160%(206mm vs 129mm).

USA test APBC@2000m penetration is 129mm, am I right? Or 144mm?

 

[TempestMKV]

But as can be seen the 122mm D25T wasn't a very good AT gun, its' performance was close to that of the 75mm KwK42 L/70 on the Panther while being much heavier and much much slower to reload. In short the D25T was more of an anti personnel weapon than an anti tank weapon.

The Soviets should've concentrated more on their 100mm D-10 AT gun, which was an able design in the AT role, featuring better performance than the 122mm D25T while being lighter and faster to reload.

USSR had Su100 in WWII, so needn't JS-100.

 

[Soren]

Tempest,

The point is that if the Soviets wanted a tank effective in tank vs tank combat then they should've chosen the 100mm D-10T as the main armament instead of the 122mm D-25T. And since all their tanks were at a serious disadvantage compared to German tanks when it came to firepower then they should've concentrated on the 100mm D-10T.

That they built a tank destroyer with the gun (D10T) doesn't mean it wasn't a mistake not putting it on their battle tanks, cause on the battlefield the rotatable turret on a battle tank gives it a huge advantage over any SPG.

 

[Soren]

This is russian resource of APBC shell. Note that penetration comparation between 100m vs 2000m is 212mm: 152mm,ratio is 139%,while DDR corresponding ratio is 136%( APBC,160mm:118mm) ,but USA test's ratio is 160%(206mm vs 129mm).

First of all the Soviets never were too thurough when it came to tests, and secondly the test plates the Soviets used were of pretty poor quality, which woud explain the difference.

USA test APBC@2000m penetration is 129mm, am I right? Or 144mm?

At 2000m, with the APBC round, the D25T penetrated on average 129mm of vertical 240 BHN RHA armour in US tests at the Aberdeen proving grounds.

 

[TempestMKV]

First of all the Soviets never were too thurough when it came to tests, and secondly the test plates the Soviets used were of pretty poor quality, which woud explain the difference.




At 2000m, with the APBC round, the D25T penetrated on average 129mm of vertical 240 BHN RHA armour in US tests at the Aberdeen proving grounds.

Anyway, DDR data and USA test conflict each other.

 

[Soren]

Yes cause the US tests were likely done against higher quality plates (Seeing that the DDR only had access to Soviet test plates which often were of dubious quality). Furthermore, seeing that the tests were run in the 60's, they might have been using newer type AP projectiles with better penetrative performance than those used during WW2.

 

[alejandro_]

Soren

12.2cm D-25T L/43

Projectile weight: 25 kg BR-471B APC
Sectional Density: 1.679
Muzzle Velocity: 780 m/s
Total Kinetic Energy: 7605 KJ
Kinetic Energy pr. cm^2: 65 KJ

Performance against 90 degree 240 BHN RHA armour:
500m = 183mm
1,000m = 162mm
1,500m = 144mm
2,000m = 129mm
2,500m = 118mm
3,000m = 108mm

Are you sure its a BR-471B? This type was described as APBC. Performance should be similar to 100mm. By the way, I think BR-412D is APCBC.

 

[tomo pauk]

First of all the Soviets never were too thurough when it came to tests, and secondly the test plates the Soviets used were of pretty poor quality, which woud explain the difference.
...

Soren
While I do found you posts worth reading, stating that Soviets were "never were too thurough when it came to tests" is silly, to say at least.

 

[Soren]

Soren
While I do found you posts worth reading, stating that Soviets were "never were too thurough when it came to tests" is silly, to say at least.

No not really tomo, that's sadly just how it was, and their tests with German tanks stand as firm testamonies to this.

 

[alejandro_]

No not really tomo, that's sadly just how it was, and their tests with German tanks stand as firm testamonies to this.

Can you be more specific?

 

[Soren]

Well take their tests against a captured Tiger Ausf.B, they started out by taking the thing apart removing the gun, tracks etc etc... and then they fired loads of 7.62cm, 8.5cm 15.2cm shells at the thing, after which they fired the 12.2cm D-25T 10cm D-10 gun at it. From this they concluded that the 12.2cm gun would be effective against the Tiger's glacis plate cause large pieces of armour cracked and fell off. They somehow ignored the fact that they prior to firing the 12.2cm 10cm guns had fired numerous (over 20) 7.62, 8.5 15.2 cm shell at the glacis, greatly weakening the structure.

They didn't do like other nations such as Germany, US UK did, which was pick a couple of guns they assumed could maybe penetrate the armour to begin with and then fire them one by one at the tank. No they chose to hammer the thing with a multitude of different caliber guns until the thing was ready to fall apart, and THEN they started firing their most powerful guns at it, the very guns which performance needed to be tested against the tank the most. Not a very thurough test if you ask me.

 

[m kenny]

Well take their tests against a captured Tiger Ausf.B, they started out by taking the thing apart removing the gun, tracks etc etc..

This is normal practice. Lots of stuff is taken away for proper technical examination. See here how another monster was stripped down.

They didn't do like other nations such as Germany, US UK did,

Look on page 20 of Jentz Tiger I&II, Combat Tactics. I see one British test hit on a Tiger that is numbered 114.

 

[m kenny]

 

[Soren]

Way to go by picking comments out of context m_kenny. Unlike the Soviets the British, Germans US actually started out with guns they had an assumption could penetrate the armour at some range. The Soviets just peppered the tank until it failed in certain areas, they didn't even take into account that they were weakening the structure.

This is normal practice. Lots of stuff is taken away for proper technical examination. See here how another monster was stripped down

Normal to what degree exactly? Look at the Tiger the British tested their guns against, the gun is still on that tank, and so are the tracks as far as I can see.