Bismarck Tirpitz Scharnhorst vs King George V Prince of Wales Hood

[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

[dunmunro]

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

You're missing the point. Even if the test against the KM armour was flawed, the test against RN armour was not flawed and it showed that 299mm of RN armour could be penetrated by the RN 14/45 at ~1460fps @ 30d target angle. There are differences of opinion but in all probability there wasn't much to chose from between RN and KM armour.

[Garyt]

There are differences of opinion but in all probability there wasn't much to chose from between RN and KM armour.

I'd guess that to be correct. And likely both were better than US or Japanese armor.

and it showed that 299mm of RN armour could be penetrated by the RN 14/45 at ~1460fps @ 30d target angle.

I see your point. There are disprepancies between this info, Navweaps and Okun's formula. Not sure what to make of it.

[Christian VII.]

I don't know if I find it odd that a 28 cm gun could out penetrate a 35 cm gun, esp. when the muzzle velocities are considered. The 28cm C/34's did after all fire their projectiles ~120 m/s faster, which would also help reduce the impact angle vs vertical belt armour.

Thus I don't find it unlikely that the 28cm C/34's outperformed the 35cm Mark VII's versus belt armour, and I don't really see any test results that would downright disprove this.

Thorsten seems to have more accurate data than me on these matter though, so it would be interesting to hear his opinion :)

[dunmunro]

I don't know if I find it odd that a 28 cm gun could out penetrate a 35 cm gun, esp. when the muzzle velocities are considered. The 28cm C/34's did after all fire their projectiles ~120 m/s faster, which would also help reduce the impact angle vs vertical belt armour.

Thus I don't find it unlikely that the 28cm C/34's outperformed the 35cm Mark VII's versus belt armour, and I don't really see any test results that would downright disprove this.

Thorsten seems to have more accurate data than me on these matter though, so it would be interesting to hear his opinion :)

I showed how, at 20k yds, the SV of the two guns only varies by about 12 m/s:


14in: = ~1610fps (491m/s) with 721.2kg shell
28cm = ~503m/s or (1650fps) with 330kg shell

It would be absolutely amazing for the 28cm gun to match or exceed the RN 14/45.

[Christian VII.]

But we also need to consider the impact angle at said ranges as they have an effect on the relative armour thickness. Hence if a projectile strikes at a lower angle then it will also be able to defeat a thicker plate as compared to when striking it at a higher angle.

In other words a higher muzzle velocity is beneficial for performance against belt armour as it reduces the AOF and therefore impact angle at range.

In terms of penetration at the same impact angles I have no doubt that the 14" Mark VII's will outperform the 11" C/34 at 20,000 yards, but in reality they won't be hitting their target at the same angle hence my reservations in regards a blunt statement on which gun was better at that range - esp. as there's conflicting data on this.

[dunmunro]

But we also need to consider the impact angle at said ranges as they have an effect on the relative armour thickness. Hence if a projectile strikes at a lower angle then it will also be able to defeat a thicker plate as compared to when striking it at a higher angle.

In other words a higher muzzle velocity is beneficial for performance against belt armour as it reduces the AOF and therefore impact angle at range.

In terms of penetration at the same impact angles I have no doubt that the 14" Mark VII's will outperform the 11" C/34 at 20,000 yards, but in reality they won't be hitting their target at the same angle hence my reservations in regards a blunt statement on which gun was better at that range - esp. as there's conflicting data on this.

The AoF for the 28cm at 20k yds = 14.5d while AoF for the 14in/45 @ MV=2400fps= 18.2d, however at MV=2475fps I would estimate that the AoF would = ~17d.

The difference between the 28cm at 14.5d and 17d = ~10mm, so this not going to give it anything like the difference that it would need to overcome a 14in/45. At 1610fps and 17d AoF the 14in/45 would be capable of intact penetration of ~370-400mm.

[Christian VII.]

But we also need to consider the impact angle at said ranges as they have an effect on the relative armour thickness. Hence if a projectile strikes at a lower angle then it will also be able to defeat a thicker plate as compared to when striking it at a higher angle.

In other words a higher muzzle velocity is beneficial for performance against belt armour as it reduces the AOF and therefore impact angle at range.

In terms of penetration at the same impact angles I have no doubt that the 14" Mark VII's will outperform the 11" C/34 at 20,000 yards, but in reality they won't be hitting their target at the same angle hence my reservations in regards a blunt statement on which gun was better at that range - esp. as there's conflicting data on this.

The AoF for the 28cm at 20k yds = 14.5d while AoF for the 14in/45 @ MV=2400fps= 18.2d, however at MV=2475fps I would estimate that the AoF would = ~17d.

The difference between the 28cm at 14.5d and 17d = ~10mm, so this not going to give it anything like the difference that it would need to overcome a 14in/45. At 1610fps and 17d AoF the 14in/45 would be capable of intact penetration of ~370-400mm.

370-400mm at 20,000 yards ? Are you sure about that?

Seems extremely unlike considering that the considerably more powerful 38cm SK C/34's were capable of penetratiing 392mm of armour at 17.8 deg AOF @ 502 m/s (1650 fps) in German trials. Either that or the British must have been shooting against some rather poor quality plates.

Navweaps has the 14" Mark VII's listed as penetrating 285mm of armour at 20,000 yards based on USN calculations, that's quite some ways from 370-400 mm.

[dunmunro]

But we also need to consider the impact angle at said ranges as they have an effect on the relative armour thickness. Hence if a projectile strikes at a lower angle then it will also be able to defeat a thicker plate as compared to when striking it at a higher angle.

In other words a higher muzzle velocity is beneficial for performance against belt armour as it reduces the AOF and therefore impact angle at range.

In terms of penetration at the same impact angles I have no doubt that the 14" Mark VII's will outperform the 11" C/34 at 20,000 yards, but in reality they won't be hitting their target at the same angle hence my reservations in regards a blunt statement on which gun was better at that range - esp. as there's conflicting data on this.

The AoF for the 28cm at 20k yds = 14.5d while AoF for the 14in/45 @ MV=2400fps= 18.2d, however at MV=2475fps I would estimate that the AoF would = ~17d.

The difference between the 28cm at 14.5d and 17d = ~10mm, so this not going to give it anything like the difference that it would need to overcome a 14in/45. At 1610fps and 17d AoF the 14in/45 would be capable of intact penetration of ~370-400mm.

370-400mm at 20,000 yards ? Are you sure about that?

Seems extremely unlike considering that the considerably more powerful 38cm SK C/34's were capable of penetratiing 392mm of armour at 17.8 deg AOF @ 502 m/s (1650 fps) in German trials. Either that or the British must have been shooting against some rather poor quality plates.

Navweaps has the 14" Mark VII's listed as penetrating 285mm of armour at 20,000 yards based on USN calculations, that's quite some ways from 370-400 mm.

370-400mm was an interpolation of the RN trials results for 12in armour at 30 and 40d target angles.

Please use 30d AoF so we can compare directly to the RN results.

Why do you state that the 38cm C/34 was "considerably more powerful"? The 14in shell is relatively heavier per unit of frontal area than the 38cm and it retains it's velocity better. The heavier unit frontal area aids in penetration.

The 38cm C/34, according to the GKDOS 100 penetration table, can penetrate, intact, 300mm at 30d @~485 m/s.

I think you have to realize that the penetration data on the navweaps weapon data pages is based upon an arcane USN formula that just doesn't work. I've provided you access to real world trials of the 14in/45 against both RN and KM armour and these results better match the data found here:
http://www.navweaps.com/index_nathan/Pe ... _index.htm

but there are still variations.

If you look again here:
http://www.panzer-war.com/Naab/NAaB.html

Towards the bottom of the page, you'll find more actual penetration data performed upon actual KM, USN and RN armour plate.

[Christian VII.]

The 380mm SK C/34's still have a noticably higher energy concentration than the 356mm Mark VII's though:

800 kg @ 820 m/s: 268960 kj
268960 / 1134 sq.cm = 237 kj/sq.cm[

721.2 kg @ 750 m/s: 202837 kj
202837 / 995 sq.cm = 203 kj/sq.cm

Velocity at 18,500 m (20,231 yards) for the 380mm C/34 AP round was ~527 m/s, and ~488 m/s for the 356mm Mark VII:

800 kg @ 527 m/s: 111091 kj
111091 / 1134 sq.cm = 98 kj/ sq.cm

721.2 kg @ 488 m/s: 86933 kj
86933 / 995 sq.cm = 87 kj/sq.cm

AOF at this range was ~14.4 deg for the 380mm L4.4 round, and ~17.3 deg for the 356mm Mark VII round.

[dunmunro]

The 380mm SK C/34's still have a noticably higher energy concentration than the 356mm Mark VII's though:

800 kg @ 820 m/s: 268960 kj
268960 / 1134 sq.cm = 237 kj/sq.cm[

721.2 kg @ 750 m/s: 202837 kj
202837 / 995 sq.cm = 203 kj/sq.cm

Velocity at 18,500 m (20,231 yards) for the 380mm C/34 AP round was ~527 m/s, and ~488 m/s for the 356mm Mark VII:

800 kg @ 527 m/s: 111091 kj
111091 / 1134 sq.cm = 98 kj/ sq.cm

721.2 kg @ 488 m/s: 86933 kj
86933 / 995 sq.cm = 87 kj/sq.cm

AOF at this range was ~14.4 deg for the 380mm L4.4 round, and ~17.3 deg for the 356mm Mark VII round.

It certainly is higher, but the KM 38cm and RN 14/45 are much closer to each other than the KM 28cm is to RN 14/45.

[Christian VII.]

The 380mm SK C/34's still have a noticably higher energy concentration than the 356mm Mark VII's though:

800 kg @ 820 m/s: 268960 kj
268960 / 1134 sq.cm = 237 kj/sq.cm[

721.2 kg @ 750 m/s: 202837 kj
202837 / 995 sq.cm = 203 kj/sq.cm

Velocity at 18,500 m (20,231 yards) for the 380mm C/34 AP round was ~527 m/s, and ~488 m/s for the 356mm Mark VII:

800 kg @ 527 m/s: 111091 kj
111091 / 1134 sq.cm = 98 kj/ sq.cm

721.2 kg @ 488 m/s: 86933 kj
86933 / 995 sq.cm = 87 kj/sq.cm

AOF at this range was ~14.4 deg for the 380mm L4.4 round, and ~17.3 deg for the 356mm Mark VII round.

It certainly is higher, but the KM 38cm and RN 14/45 are much closer to each other than the KM 28cm is to RN 14/45.

At the muzzle the 28cm C/34 actually features a higher energy concentration than the 14" Mark VII:

336 kg @ 890 m/s: 133072 kj
133072 / 615 sq.cm = 216 kj/sq.cm

[alecsandros]

I don't know if I find it odd that a 28 cm gun could out penetrate a 35 cm gun, esp. when the muzzle velocities are considered. The 28cm C/34's did after all fire their projectiles ~120 m/s faster, which would also help reduce the impact angle vs vertical belt armour.

You can't find it odd, because it is wrong.

At 20km the 283mm gun coudl perforate about 280mm of vertical KC armor. At same range the 356mm gun could perforate about 360mm of British cemented armor.

[Christian VII.]

I don't know if I find it odd that a 28 cm gun could out penetrate a 35 cm gun, esp. when the muzzle velocities are considered. The 28cm C/34's did after all fire their projectiles ~120 m/s faster, which would also help reduce the impact angle vs vertical belt armour.

You can't find it odd, because it is wrong.

At 20km the 283mm gun coudl perforate about 280mm of vertical KC armor. At same range the 356mm gun could perforate about 360mm of British cemented armor.

I don't know, thus I think I can find it odd that one form of calculation, the USN one, has the 280mm C/34 outperform the 356mm Mark VII, can I not?

I don't know how KC armour compared with British cemented armour either, and wether one gun was better against one type of armour than the other. It depends on the shape and composition of the respective penetrators, as well as the size & composition of the target plate.

But at least in terms of raw energy concentration the 280mm C/34 actually holds a slight edge initially.

[alecsandros]

I don't know if I find it odd that a 28 cm gun could out penetrate a 35 cm gun, esp. when the muzzle velocities are considered. The 28cm C/34's did after all fire their projectiles ~120 m/s faster, which would also help reduce the impact angle vs vertical belt armour.

You can't find it odd, because it is wrong.

At 20km the 283mm gun coudl perforate about 280mm of vertical KC armor. At same range the 356mm gun could perforate about 360mm of British cemented armor.

I don't know, thus I think I can find it odd that one form of calculation, the USN one, has the 280mm C/34 outperform the 356mm Mark VII, can I not?

I don't know how KC armour compared with British cemented armour either, and wether one gun was better against one type of armour than the other. It depends on the shape and composition of the respective penetrators, as well as the size & composition of the target plate.

But at least in terms of raw energy concentration the 280mm C/34 actually holds a slight edge initially.

Nathan Okun modeled both guns, you probably know the results.

In his own words, his model comes withing 13% of British field tests and within 10% of American field tests.

Most contemporary research that I know of puts British CA and Krupp KC n/A at rough parity in terms of stoping power of BB caliber shells.

The 356mm/L45 projectile is simply much to powerfull to compare it to the German 283/L55 projectile.

Modeling shows a difference of ~ 50% in penetration of same type of plate (either both German or both British) at 20km.

Even allowing tolerances of up to 10-15%, which can account for different metodologies of testing between countries, different properties between plates, different proprieterties between projectiles, the 356mm is head and shoulders above
the 283mm gun.

--

The 283mm gun has a higher initial velocity than the 356mm gun, that's why it has that initial energy.