Bismarck Tirpitz Scharnhorst vs King George V Prince of Wales Hood

[dunmunro]

A 300kg projectile traveling at 500m/s however has far fewer chances of knocking out the same turret in the same circumstances, because it carries 2.5 times less kinetical energy.

One thing to remember though is that kinetic energy is equal to mass times the square of velocity,

Take a look a Scharnhorst's 11" gun, and it has about 15% more velocity than say the 14" gun from the Prince of Wales. Even with the lighter shell, the Scharnhorst should have similar kinetic energy to the Prince of Wales guns.

Heavier shells retain their velocity better than lighter shells. PoW's 14in/1590lb shells will have far more KE at typical battle ranges than the KM 730lb shells:

20K yds

14in: = ~1610fps (491m/s) with 721.2kg shell = 86933808j
28cm = ~500m/s or (1640fps) with 330kg shell = 41250000j or about 47% of the RN 14in. And the RN shell has a much heavier burster charge of 48lb versus 14.6lb in Scharnhorst

[paul.mercer]

Gentlemen,
Re Repulse and Renown being in the battle, I still think that to have them in the battle line would be a mistake, but if they stood back they would be in a very good position to intervene and attack or finish off any damaged German ships, particularly if some of our ships had taken a battering. Remember that Renown took on both Gneisnau and Scharnhorst and sent them packing with several hits on Gneisnau.

[Christian VII.]

The 28cm C/34's were capable of penetrating 335mm of belt armour at 15 km at a 30 deg impact angle right? Hence I assumed they would be able to penetrate the KGV's belt below 16 km.

Either way it would be the HE shells that would do most of the damage anyway, and the Scharnhorst enjoyed a noticable advantage in rate of fire. This coupled with slightly higher accuracy and I'd assume KGV rather quickly would be forced to retreat due to damage?

[Christian VII.]

A 300kg projectile traveling at 500m/s however has far fewer chances of knocking out the same turret in the same circumstances, because it carries 2.5 times less kinetical energy.

One thing to remember though is that kinetic energy is equal to mass times the square of velocity,

Take a look a Scharnhorst's 11" gun, and it has about 15% more velocity than say the 14" gun from the Prince of Wales. Even with the lighter shell, the Scharnhorst should have similar kinetic energy to the Prince of Wales guns.

Heavier shells retain their velocity better than lighter shells. PoW's 14in/1590lb shells will have far more KE at typical battle ranges than the KM 730lb shells:

20K yds

14in: = ~1610fps (491m/s) with 721.2kg shell = 86933808j
28cm = ~500m/s or (1640fps) with 330kg shell = 41250000j or about 47% of the RN 14in. And the RN shell has a much heavier burster charge of 48lb versus 14.6lb in Scharnhorst

I have 476 m/s for the 14" Mark VII's at 20,000 yards? (510 m/s for the 28cm C/34)

336.0 kg @ 510 m/s = 43.7 MJ
721.2 kg @ 476 m/s = 81.7 MJ

Either way kinetic energy alone is far from the whole story, it's also about how you concentrate that energy. A smaller caliber slug will benefit from better penetration at similar levels of kinetic energy simply due to a higher energy concentration, which is also why tanks use sub caliber sabot rounds for maximum armour penetration.

Looking at the circular surface area of both calibers we see an area of ~615 sq.cm for the 11" shell and ~995 sq.cm for the 14" shell, which means that the 14" shell has significantly more area for the kinetic energy to distribute itself.

This is probably one of the reasons why the 28cm C/34 actually outperforms the 14" Mark VII in belt armour penetration at 20k yards distance according to some comparisons, whilst obviously the 14" guns outperforms the 28cm gun in deck penetration.

In other words the Scharnhorst & KGV were apparently both immune to belt penetrations from each others guns past 15 km. Hence I believe the ship that can first incapacitate the other by sweeping the decks has the advantage, and due to its higher rate of the fire the Scharnhorst surely has the advantage here.

[Garyt]

Looking at Belt penetration numbers, Scharnhorst penetrates 11.47" at 20,013 yards, POW 11.2" at 20,000 yards.

Horizontal armor on the two vessels was fairly similar. I'd say the only thing the Scharnhorst needs to do is close the gap quickly to get inside of deck trajectory shells, and/or hope it HE rounds and higher ROF can do as much or more damage than any deck penetrating hits from the POW.

It seems the Scharnhorst would have to be at about 34,000 meters to substantially have a chance to penetrate the POW deck, while the POW only needs to be at 26,000 meters to penetrate the Scharnhost's deck.

[dunmunro]

Heavier shells retain their velocity better than lighter shells. PoW's 14in/1590lb shells will have far more KE at typical battle ranges than the KM 730lb shells:

20K yds

14in: = ~1610fps (491m/s) with 721.2kg shell = 86933808j
28cm = ~500m/s or (1640fps) with 330kg shell = 41250000j or about 47% of the RN 14in. And the RN shell has a much heavier burster charge of 48lb versus 14.6lb in Scharnhorst

I have 476 m/s for the 14" Mark VII's at 20,000 yards? (510 m/s for the 28cm C/34)

336.0 kg @ 510 m/s = 43.7 MJ
721.2 kg @ 476 m/s = 81.7 MJ

Either way kinetic energy alone is far from the whole story, it's also about how you concentrate that energy. A smaller caliber slug will benefit from better penetration at similar levels of kinetic energy simply due to a higher energy concentration, which is also why tanks use sub caliber sabot rounds for maximum armour penetration.

Looking at the circular surface area of both calibers we see an area of ~615 sq.cm for the 11" shell and ~995 sq.cm for the 14" shell, which means that the 14" shell has significantly more area for the kinetic energy to distribute itself.

This is probably one of the reasons why the 28cm C/34 actually outperforms the 14" Mark VII in belt armour penetration at 20k yards distance according to some comparisons, whilst obviously the 14" guns outperforms the 28cm gun in deck penetration.

In other words the Scharnhorst & KGV were apparently both immune to belt penetrations from each others guns past 15 km. Hence I believe the ship that can first incapacitate the other by sweeping the decks has the advantage, and due to its higher rate of the fire the Scharnhorst surely has the advantage here.

476m/s is correct if the MV = 2400fps but the new gun MV for the 14in/45 is 2475fps. 20k yds = 18288m and from the GKDOS table for the 28cm gun this equals 500m/s almost exactly.

Your circular surface area calculation shows that the 14in shell has ~55% more surface area but then it has 104% more KE so the KE per square area is much higher than for the 28cm shell.

At 30 deg target angle the KM 28cm has ~235mm penetration with 500m/s SV. To penetrate 300mm @ 30d the 28cm gun requires 700m/s.

At 30deg target angle the 14in/45 can penetrate (12in) ~300mm at 1460fps (444m/s) The 14in/45 can penetrate 14in @ 30d (~350mm) at ~1800fps (~550m/s) (data from proofing trials)

theoretical ROF = 20RPM for PoW = KE delivered = 1740MJ
and 31.5RPM for Scharnhorst = KE delivered = 1300MJ

However the 14in shell delivers ~3.3x times as much explosive per hit which will inflict many times greater damage per hit.




The 28cm gun doesn't outperform the 14in/45 at any range, especially not at 20k yds.

[Christian VII.]

According to the penetration data I have available the 28cm C/34 infact does outperform the 14" Mark VII at 20,000 yards vs belt armour, the 28cm C/34 penetrating 291mm of armour to the 285mm of the 14" Mark VII.

Against German plates the 28cm C/34 penetrated 348mm of armour at a 652 m/s SV, so 700+ m/s for 300mm can't be right, you must be reading something wrong.

The 14" shell's circular area is 63% higher, but obviously that's just part of the equation, there's more to it than just that but it was just a way to explain that kinetic energy alone is far from the determining factor. Another factor is shell design and material.

[dunmunro]

According to the penetration data I have available the 28cm C/34 infact does outperform the 14" Mark VII at 20,000 yards vs belt armour, the 28cm C/34 penetrating 291mm of armour to the 285mm of the 14" Mark VII.

Against German plates the 28cm C/34 penetrated 348mm of armour at a 652 m/s SV, so 700+ m/s for 300mm can't be right, you must be reading something wrong.

The 14" shell's circular area is 63% higher, but obviously that's just part of the equation, there's more to it than just that but it was just a way to explain that kinetic energy alone is far from the determining factor. Another factor is shell design and material.

Remember that I used data for a 30deg target angle.

Don't you find it odd that an 28cm gun could out penetrate a 35cm gun?

I used the official penetration tables for the KM 28cm C/34 and the data from RN WW2 trials of the 14in/45 against actual armour and these trials were typically conducted with the armour at a 30deg target angle, as this is closer to combat conditions than perpendicular penetration.

[alecsandros]

According to the penetration data I have available the 28cm C/34 infact does outperform the 14" Mark VII at 20,000 yards vs belt armour, the 28cm C/34 penetrating 291mm of armour to the 285mm of the 14" Mark VII.

What source ?

I find it extremely dubious to say the least.

[alecsandros]

The 14" shell's circular area is 63% higher, but obviously that's just part of the equation, there's more to it than just that but it was just a way to explain that kinetic energy alone is far from the determining factor. Another factor is shell design and material.

shell circular area is meaningless in terms of non-penetrating turret hits, as what matters is the energy that hits the structure, and not the surface over which the impact occurs. Surface matters for penetration calculations, not for impact damage*.


* Of course that is not the whole story. Head shape, crh, the method of attaching the perforating CAP to the body, hardness of CAP and body, variations between them, way of which mass is distributed inside the shell, center of mass, actual obliquity at impact point, etc, all play a part in the penetration / perforation process. In all relevant cases (usual battle range, usual target angle, standard WW2 guns, projectiles and armor plates), the larger shell outperforms the smaller shell in terms of penetration capabilities , assuming the same impact conditions

[Garyt]

What source ?

I find it extremely dubious to say the least.

Not sure where Christian got his info, but Navweaps shows the 28cm C/34 outperforming the 14" Mark VII slightly on belt penetration at most ranges.

[Thorsten Wahl]

(28cm C/34) at 20 kyard ~18 km
according Unterlagen zur Bestimmung der Hauptkampfentfernung Schlachtschiffe Scharnhorst/Gneisenau
V~ 510 m/s and AOF ~14,5°

penetration ~275 mm heil (penetration, projectile whole and projectile fit to burst and also possess some remaining velocity)

penetration ~290 mm Grenzschuss (penetration, projectile broken at least 50% of shell fragments behind plate)

[dunmunro]

(28cm C/34) at 20 kyard ~18 km
according Unterlagen zur Bestimmung der Hauptkampfentfernung Schlachtschiffe Scharnhorst/Gneisenau
V~ 510 m/s and AOF ~14,5°

penetration ~275 mm heil (penetration, projectile whole and projectile fit to burst and also possess some remaining velocity)

penetration ~290 mm Grenzschuss (penetration, projectile broken at least 50% of shell fragments behind plate)

The same document that gives you AoF also gives you SV. At 17500m SV = ~515 m/s and at 18500m SV = 500 m/s so at 18288m SV = ~503 m/s

I can't compare the RN 14/45 with the 28cm c/34 at 14.5d target angle because I don't have data for that, as all proofing trials were done at 30deg (60 deg auftreffwinkel) target angle.

[dunmunro]

What source ?

I find it extremely dubious to say the least.

Not sure where Christian got his info, but Navweaps shows the 28cm C/34 outperforming the 14" Mark VII slightly on belt penetration at most ranges.

Yes, and that data for the RN gun is completely wrong. Navweaps does give a set of penetration tables here:

http://www.navweaps.com/index_nathan/Pe ... _index.htm

that at least make some effort to conform to actual actual trial results although they are not exact in anyway, and are similar to the output produced by NAaB:
http://www.panzer-war.com/Naab/NAaB.html

however, please note the performance of the 14/45 against KM armour as given in actual trials and reproduced on the above webpage:
http://www.panzer-war.com/Naab/Tripitz1.jpg
the deduced SV for penetration of 12.5in (~318mm) KM plate @ 30d is 1370fps and the deduced penetration limit for RN 11.76in (299mm) armour @ 30d is 1457 fps.

Doubtless there is plate to plate and shell to shell variation, but it seems clear what the RN 14/45 could do against actual armour.

[Garyt]

however, please note the performance of the 14/45 against KM armour as given in actual trials and reproduced on the above webpage

My understanding is that these tests were fairly flawed, as they used small plates of KM armor. According to Nathan Okun, the use of smaller plates degrade the armor's performance to resist penetration.

What I find interesting is they also tested British armor in this test, full a full sized unit. They then used this testing to state British armor was superior to German armor. Sound like some homer based testing going on