dunmunro wrote: ↑
Tue Sep 11, 2018 9:28 am
Again, by definition the shells, with their flat trajectory have to then find their way into a magazine, and as we've seen this is going to be very difficult as the shells will strike the deck/hull plating and then tear through a lot of ship's structure prior to striking the armoured bulkhead. Consequently the odds of a functioning shell making it all the way to a magazine is nil. In fact the odds of a functioning shell even making it to the armoured bulkhead before detonating are very low.
75deg obliquity when striking the hull, yes, it's probable.
About 30deg obliquity when striking the forward armored bulkhead (15deg A0F + 15deg lateral obliquity, as Rodney wasn't exactly head on).
At 18000meters , 380mm APC shell falls at angle of 13,9deg with velocity of 532m/s. First impact, or impacts , with hull elements will strip the windscreen off (83kg mass) and initiate the fuze. The remaining mass of 717kg will push through the structure until hitting the bulkhead (305 or 203mm thickness depending on the trajectory).
Fuze is considered in 'Loss of HMS Hood ' (http://www.zhanliejian.com/navweaps/INRO_Hood_p3.htm#62
) as follows:
62 Evidence from U.S. sources indicates that such an increase in delay would not be unusual. For example, U.S. Navy specifications for the Base Detonating Fuze Mark 21 considered the fuze action satisfactory if the detonation occurred between 0.030 and 0.070 seconds after impact when set for a nominal 0.033 second delay. British experience at the River Plate and elsewhere lead them to estimate the effective German fuze delay as being about 0.05 seconds.
0,03sec with 532m/s = 15,96meters (52,67feet) (in reality less then that as every obstacle would slightly decrease velocity, and perforation of armored bulkhead would reduce it very much)
0,05sec with 532m/s = 26,60meters (87,78feet) (" …………………….")
0,07sec with 532m/s = 37,24meters (122,90feet) (" …………………….")
Therefore it all rests on the actual way in which the fuze would work (and IF it would work - although having a dud projectile crashing at 400m/s into the forward main magazine can also produce catastrophic damage. At Denmark Strait, a dud 380mm shell hit Prince of Wales ~8meters below the waterline, suggesting that the underwater trajectory was about 40 meters (132feet), based on range 16km, angle of fall ~12degrees, depth of hit 8meters. Sin(12degrees) is 0,20).