Intersting stuff. Cant wait to see some sources though. There are plenty of other people that should post there sources here as well!
Schwarzpanzer's sources
- Thread starter Soren
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Henk
Master Sergeant
Oh boy we have something no one else ever heard of except for one person.
delcyros
Tech Sergeant
plan_D said:
There were two prototypes of T-34 with 100mm D10. The first suffered from too heavy recoil forces, the second was found to be excellent. Nethertheless the project was postponed because of mass production concerns. Subsequent development lead to the T44 with a somehow smaller main gun.
regards,
lesofprimus
Brigadier General
So why the fu*k would u compare what could have happened to the King with a theoretical tank??? Thats just plain stupid....
Agreed
delcyros
Tech Sergeant
It all belongs to the artelleristic performance of the D10. This gun was in service for several tank hunters. Nethertheless, I earlier stated that even the 85 mm D 5 of the T-34-85 will have a reasonable chance to defeat the turret front. However, running my calculators shows that it cannot do. The necessary impact velocity exceeds the muzzle velocity, but not by much (24 m/s or ~ 80 fps are missing). If we factor nose shatter, the gap widens significantly.
delcyros
Tech Sergeant
Never mind, Plan_D, the comparison was biased, agreed.
it all belongs to the artelleristic performance of the tank gun. The D10 has a superior AP-performance and was widely used in tank hunters.
Compare it with the 122mm D25 of the JS-II:
At ~1300 m distance the impact velocity is 2273 fps and the aof is .78 deg, allowing for penetration with a shattered AP-cap (projectile nose suffers no or little damage), altough only barely: 2254 fps are necessary to defeat the turret front plate. Differences in barrel wear (=MV) or target angle or plate properties may cause a somehow lower performance, but there is enough plausibility (>80%) for penetration at closer distances than ~1000 m. (compare: 1390 m for the D10 with a projectile suffering nose shatter)
it all belongs to the artelleristic performance of the tank gun. The D10 has a superior AP-performance and was widely used in tank hunters.
Compare it with the 122mm D25 of the JS-II:
At ~1300 m distance the impact velocity is 2273 fps and the aof is .78 deg, allowing for penetration with a shattered AP-cap (projectile nose suffers no or little damage), altough only barely: 2254 fps are necessary to defeat the turret front plate. Differences in barrel wear (=MV) or target angle or plate properties may cause a somehow lower performance, but there is enough plausibility (>80%) for penetration at closer distances than ~1000 m. (compare: 1390 m for the D10 with a projectile suffering nose shatter)
- Thread starter
- #30
The 122mm L/43 D-25T would penetrate no more than 183mm of vertical 240BHN RHA armor at 500m. For comparison's sake the 88mm L/71 Kwk43 achieved the same at ~1,800m distance, penetrating 176mm of vertical 240BHN RHA armor at 2,000m.
- Results achieved at the Aberdeen proving grounds.
- Results achieved at the Aberdeen proving grounds.
delcyros
Tech Sergeant
...and now You have to factor that 240 BRH RHA is a lot superior to the armour used in the turret front, which prooved to be soft&brittle due to lack in some metals necessary to make a plate beeing hard ductile. The plates used in the Aberdeen prooving ground were standart US homogenious plates, undoubtly the best of the world by this time (and for plates under 8" thickness).
That´s why I use to recalculate for specific shell/plate properties, altough I also use assumptions in some aspects (shell metal properties to name one), results will differ from plate to plate and little is known about the circumstances of impact. Note that in case of the turret front there is a large central hole for the tank gun. This hole doesn´t impaire the resistance of the plate but the ability to move sideways (elongation) under impact stress (the closer the impact is on a plate edge, the more reduced is the elongation). That´s one reason why single, large plates are superior to many small ones welded together.
I must admit that the possibility arises that my metal properties are generally too low, since the important plate elongation ability I took, is always measured from the plate edges (wouldn´t be wise to cut samples from the middle of an expensive plate), implying that an impact on the middle would result in better plate resistance, generally.
I do not question that the 8.8 cm KWK/L71 is the best tank gun of ww2.
Even the JS-II almost has no immune zone to it:
upper hull, front (120mm sloped back 30 deg): penetration up to 4170 m, no nose shatter
middle hull, front (60 mm sloped back 73 deg): not possible, far beyond proofing angle for 8.8 cm shells under 10000 m distance, shell will be deflected in most cases
lower hull, front (100 mm inclined 30 deg.) : penetration up to 4630 m, no nose shatter
These distances questioning that the JS-II had ANY immune zone vs 8.8cm KWK L71.
That´s why I use to recalculate for specific shell/plate properties, altough I also use assumptions in some aspects (shell metal properties to name one), results will differ from plate to plate and little is known about the circumstances of impact. Note that in case of the turret front there is a large central hole for the tank gun. This hole doesn´t impaire the resistance of the plate but the ability to move sideways (elongation) under impact stress (the closer the impact is on a plate edge, the more reduced is the elongation). That´s one reason why single, large plates are superior to many small ones welded together.
I must admit that the possibility arises that my metal properties are generally too low, since the important plate elongation ability I took, is always measured from the plate edges (wouldn´t be wise to cut samples from the middle of an expensive plate), implying that an impact on the middle would result in better plate resistance, generally.
I do not question that the 8.8 cm KWK/L71 is the best tank gun of ww2.
Even the JS-II almost has no immune zone to it:
upper hull, front (120mm sloped back 30 deg): penetration up to 4170 m, no nose shatter
middle hull, front (60 mm sloped back 73 deg): not possible, far beyond proofing angle for 8.8 cm shells under 10000 m distance, shell will be deflected in most cases
lower hull, front (100 mm inclined 30 deg.) : penetration up to 4630 m, no nose shatter
These distances questioning that the JS-II had ANY immune zone vs 8.8cm KWK L71.
- Thread starter
- #32
US test-plates were in no way the best Delcyros, they were actually abit on the soft side. German test-plates were of much better quality and more resistant than US test-plates, the German test-plates being of 260 - 300 BHN. - The best available during WWII.
delcyros
Tech Sergeant
Partly correct. They had more brinell hardness (and also deeper down the plate), making this kind of armour comparably tough. However, as a side effect of the high ability to resist being permanently deformed by a slowly-applied or rapidly-applied force on a small area, very hard materials are usually also brittle and suddenly fail over a large area when the applied force exceeds the shear or tensile strength of the material. This was a problem to most but not all german plates.
Tank armor(Improved "HIGH-%" NICKEL-STEEL with Molybdenum added), which is made of higher hardness to protect against close-range, high-velocity projectile impacts from 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 softer (=more ductile) plates.
The US homogenious plates, beeing softer, could tear and therefore deflect incoming projectiles better. In general spoken, the lower the impact obliquity, the better the german plate in comparison, the higher the impact obliquity, the better the US plates. Sound and simple.
Quality of plates differs a lot. The best tank armour quality of ww2 is represented in the thinner turret front plates of the Pz-III tanks, beeing extremely hard and still ductile (Q:1.10; E:18%). The Tiger I also has tough and ductile armour but the Panther, beeing tough, was prone to spalling effects and the Tiger-II armour in the end was both, soft&brittle. If You compare Tiger-II plate properties with those of US plates (both using acceptance limits as comparison), the US average 1944 plate is far superior.
Tank armor(Improved "HIGH-%" NICKEL-STEEL with Molybdenum added), which is made of higher hardness to protect against close-range, high-velocity projectile impacts from 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 softer (=more ductile) plates.
The US homogenious plates, beeing softer, could tear and therefore deflect incoming projectiles better. In general spoken, the lower the impact obliquity, the better the german plate in comparison, the higher the impact obliquity, the better the US plates. Sound and simple.
Quality of plates differs a lot. The best tank armour quality of ww2 is represented in the thinner turret front plates of the Pz-III tanks, beeing extremely hard and still ductile (Q:1.10; E:18%). The Tiger I also has tough and ductile armour but the Panther, beeing tough, was prone to spalling effects and the Tiger-II armour in the end was both, soft&brittle. If You compare Tiger-II plate properties with those of US plates (both using acceptance limits as comparison), the US average 1944 plate is far superior.
- Thread starter
- #34
delcyros
Tech Sergeant
In comparison to US plates, german plates were not that ductile. Part of the problem was the unsolved hydrogenium embrittlement, not noticed by german metallurgists. A plate beeing initially ductile soon becomes brittle with a significant drop in %-elongation ability (often between 1.5 and 2.5%) due to wear of use. US plates had this problem fixed by mid 1943.
Now, If you factor that the angled plates of the Tiger-II ALWAYS caused high obliquity impacts, the german plates did not well in comparisoin to what would have been possible with a 240 BRH RHA US plate of simnilar thickness.
In opposition to this, the vertical surfaces of the Tiger-I benefitted from the very hard, av. 260 BRH RHA plates, the german used by then.
Now, If you factor that the angled plates of the Tiger-II ALWAYS caused high obliquity impacts, the german plates did not well in comparisoin to what would have been possible with a 240 BRH RHA US plate of simnilar thickness.
In opposition to this, the vertical surfaces of the Tiger-I benefitted from the very hard, av. 260 BRH RHA plates, the german used by then.
- Thread starter
- #36
Delcyros, I was talking purely about test-plates, where the German test-plates were of 260-300 BHN throughout the war, compared to the US 1943 std. 220-240 BHN test-plates. - 220 BHN for plates of >127mm.
The armor quality of German tanks however went down considerably from late 44 to 45, the JagdPanther's having a frontal armor of just 200 BHN - Yet again somehow it proved immune to Allied fire, both Allied and German crews reporting that penetrations from the front were as good as impossible - One particular incident comes to mind where US M36 TD's after fruitlessly having bombarded a Jagdpanther's glacis plate from 300y away had to come within 100y to knock it out.
The armor quality of German tanks however went down considerably from late 44 to 45, the JagdPanther's having a frontal armor of just 200 BHN - Yet again somehow it proved immune to Allied fire, both Allied and German crews reporting that penetrations from the front were as good as impossible - One particular incident comes to mind where US M36 TD's after fruitlessly having bombarded a Jagdpanther's glacis plate from 300y away had to come within 100y to knock it out.
delcyros
Tech Sergeant
Correct. But I see no ductility related values in Your test samples.
To give an example about it´s importance:
T-34- front plate A (original):
45 mm sloped back to 60 deg.
Now I factor that 45 mm homogenious material with a BRH of ~450 and an elongation of 10% as usual for the somehow brittle soviet armour grade materials.
A 75 mm KWK 42 /L70 with a mv of 3100 fps and a shellweight of 15 lbs would need at least 2734 fps striking velocity to defeat the front plate. At close distance, the frontplate, despite its decent slope will be defeatable.
Using the 240 BRH US plate with high ductility (25% elongation) will give an edge of 120 fps in minimum striking velocity needed to defeat the plate, despite the somehow softer armour grade material. The plate will bend more and allows the projectile to ricochet off. The thicker the plate, the slower the impact velocity and the more slope is involved, the more important becomes ductility. Very thick plates may crack or-even worse- seperate spalling, dividing the plate. And since armour penetration is a local phenomen, such a plate has greatly reduced resistence. (A concern for all cast armour plates)
To give an example about it´s importance:
T-34- front plate A (original):
45 mm sloped back to 60 deg.
Now I factor that 45 mm homogenious material with a BRH of ~450 and an elongation of 10% as usual for the somehow brittle soviet armour grade materials.
A 75 mm KWK 42 /L70 with a mv of 3100 fps and a shellweight of 15 lbs would need at least 2734 fps striking velocity to defeat the front plate. At close distance, the frontplate, despite its decent slope will be defeatable.
Using the 240 BRH US plate with high ductility (25% elongation) will give an edge of 120 fps in minimum striking velocity needed to defeat the plate, despite the somehow softer armour grade material. The plate will bend more and allows the projectile to ricochet off. The thicker the plate, the slower the impact velocity and the more slope is involved, the more important becomes ductility. Very thick plates may crack or-even worse- seperate spalling, dividing the plate. And since armour penetration is a local phenomen, such a plate has greatly reduced resistence. (A concern for all cast armour plates)
- Thread starter
- #38
Delcyros,
Panther crews reported that a successful penetration of the T-34's glacis plate could be achieved regularly at a distance of 2,500m.
Tiger crews reported that at 1,000m (The most usual engagement range for Tiger's in the beginning), the Pzgr.39 usually tended not only to completely penetrate the glacis but also exit out the back end of the T-34 - through the engine. And mind you this is before the improved Pzgr.39/43 appeared...
Panther crews reported that a successful penetration of the T-34's glacis plate could be achieved regularly at a distance of 2,500m.
Tiger crews reported that at 1,000m (The most usual engagement range for Tiger's in the beginning), the Pzgr.39 usually tended not only to completely penetrate the glacis but also exit out the back end of the T-34 - through the engine. And mind you this is before the improved Pzgr.39/43 appeared...
delcyros
Tech Sergeant
...just wanted to point out that BRH is not the one only metal quality.