The British 15" had a very large burster charge (about the same as the WWII US 16" iirc)...the US ship has ... more destructive shells
-burster of the 2700 lb (1225 kg) US-Shell 40.9 lbs. (18.55 kg)
-burster of the german 800 kg Psgr (18.8 kg)
energy content of the german burster is about 20 % higher than the US burster.
I agree, although the US shell is throwing 50% more mass around as shrapnel once inside the ship, so rather balances out the initial destructivness of the burster with a greater mass being thrown around inside the ship after bursting.
Thoddy wrote:The main advantage the US Shell possess when fired from the 16" L/45 gun(IV 2300 fs) is its greater mass and it's somewhat better impact angle against horizontal protection.
Yes, I quite agree.
Thoddy wrote:Nevertheless a internal detonation of the german shell would also destroy a complete compartment. A restoring of lost capabilities require shipyard capacities. This was tested fullsize.
Almost all shells will destroy the compartment that they explode inside, the critical part is if that compartment is in the ships vital areas or integral to the water tight integrity of the hull. The extension to this is where the shell fragments travel to, as a red hot fragment can pass on from where the shell bursts and end up inside vital areas, as in the hit on Malaya (iirc) at Jutland that saw a fragment end up in the 6" magazine!
Thoddy wrote:From the ballistic quality of the german gun/turret one can expect about 15,5 percent hit probability of the german gun at 25 km distance if MPI is on target.
I am not too sure I follow this. 15.5% hit probability at 25km is at least 3 times, and more likely 5 times anything achieved in action, where 5% at half such a range was still considered good shooting in WWII. Against a stationary target maybe, but not in battle, no ship came close to this except in very one sided encounters at short range like Matapan where anywhere up to 80% accuracy was achieved.
Thoddy wrote:Tirpitz carried out a one hour shooting excercise(not continous but several attack figures) in autumn 1941 at this distance, wich yielded about 8 hits(AFAIK) at the moving target ship. A two impacts salvo spread at this distance looks like that
Only two hits were ever achieved at 25km or even close, so I am sceptical on claims of 15.5% hits. 1.55% might be more likely?
the data at navweaps partly underestimate the performance of the german armor piercing shell.
One should take the data KBismarck provides, as this is based on the original german fire-effect-tables.
Navweaps is fairly accurate, which served my purposes as if anything boosting the capabilities of Tirpitz only makes the equation run more against Massachussetts. It looks like the KMBismarck site uses data for a gun in 'new' condition, with optimum figures, which of course tend to run down slightly after a few rounds have been fired. Taking barrel wear into account really complicates things far too much for a basic comparison where such details are unspecified.
Thoddy wrote:The penetration performance of the US Shell published at Navweaps.com was based on a completely calculated performance using Thompson F-Formula (Origin Ordnance Pamphlet No 653
Armor pentration curves (revised) January 1942).
This formula overestimates angular performance with the error becoming higher at high obliquity
and underestimates shell performance at low obliquity.
Supp 6 910 calculated angular performance.png
The problem with the US shells at high obliquity is that pointed out by the RN when the idea of longer shells was mooted for them, the shell will often just distort and fail entirely, or riccochet off harmlessly, which makes overall performace at such angles hard to judge, as whilst one shell may achive a spectacular result by penetrating armour intact, it is possible dozens may strike and do nothing at all.
Thoddy wrote:In addition one should consider the better ballistic capabilities of german armor when compared to US armor of the same thickness.
I would agree that the German armour is generally better than US armour of an equal thickness in WWII, but there are many differing claims as to how much better it actually was, though I would suspect it was within 10% - 20% more efffective as an off the cuff figure. It is also worth looking at the article Nathun Oakun wrote (I cannot recall the title, and do not know if it is still available sadly) about how the 'X% more effective' claims may be judged, as claims are not always worded clearly.