dunmunro wrote: Garyt wrote:
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:
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.