1) As I said previously, the RN and an RN 5.25iin gunner states that the 5.25in ROF is 10-12 rounds/minute/gun:
QF 5.25 inch Mark I naval gun - Wikipedia, the free encyclopedia Navweaps or the RN...guess who I believe more?
Lets see, the HMS Euryalus manages to demonstrate 10rpm while firing with zero change in elevation,zero change in training and zero change in range when fresh out of harbor and in calm seas in view of shore.
What happened to the 12 rounds per minute?
What happens when the turret is moving in train, the guns are changing elevation, the fuse settings keep changing and the deck is rolling and pitching? rate of fire speeds up
2)The 5.25 round weighed 80 lbs and used the same fuse setters as the 4.5 and 4" guns. The 4.5 twin (also a very cramped turret by the look of it) had a ROF of 12 r/m and the 4in 15-20 r/m. Who ever wrote the navweaps article is being illogical, as the crew handling is really no different than other RN DP weapons. The shell is placed in a fuze setter and then into the loading tray, exactly the same as the 4.7in and 4.5 twin turrets.
the round did not weigh 80lbs, the projectile weighed 80lbs. + the 41lbs of charge and cartridge case.
the 4.5 weighed 55lbs plus 38.5lbs of charge and cartridge case. the early mountings used a fixed round that combined both weights together. By the way the early twin mounts in the big ships did not have ammunition hoists that came into the mounts. the ammunition hoists/conveyors were outside the mounts and crew men took the rounds from the hoists/conveyors and placed them in two scuttles on the rear of the mount. distance the rounds had to moved from the hoist to the scuttles changed as the mount rotated.
the 4" used only a fixed round that weighed 63.5lbs.
5) The USN had 1 battleship, 2 carriers, 3 heavy cruisers. 3 AA cruisers and 14 destroyers at Santa Cruz. I calculated the number of guns of each calibre for these ships and for an equal number of equivalent RN ships from the same time frame (Oct 1942).
Except you made a few mistakes and/or fudged a few things.
you left out the South Dakotas 20 5in guns or only counted them as 8 guns?
Hornet CV 8the one at Santa Cruz had eight 5 in guns.
Enterprise had eight also.
total is 36 not 24.
Both US cruisers had had their 5"/25s (not really dual purpose but dedicated AA guns) doubled to 8 per ship after being built but pre war.
16 guns instead of 8.
so US total for heavy cruisers is 24, same as the British.
No argument with the AA cruisers.
As for the 76 DP guns on the British destroyers, I think you are being more than a bit optimistic.
The twin 4.7 had the elevation problem of 40 degrees, why don't you get out your pencil and paper and protractor or better yet some trig tables.
of from the Wiki page on the 5.25" gun.
" Hodges, Tribal Class Destroyers, p32: Diagram of High Level Bomber Attack: A 240mph target, at 12 thousand feet altitude could expect to be under for fire about 75 seconds, from the time it enters the effective range of the HACS until it flies to within the minimum range of a 5.25 gun elevated to 70 degrees. A Tribal class destroyer would be able to engage the same target for about 37 seconds."
Please note that the minimum range for the 4.7 would be at a much longer distance than the 5.25". In fact (if I have done the math right) the 240mph target at 12,000ft would be safe from a 4.7in armed destroyer once it got within 4768yds of it.
The J class (and follow ups) had inferior AA fire control to the Tribals for the 4.7s.
As for the 4in gun that replace the bank of torpedo tubes, it wasn't connected to anything. It depended on the gun captain's squinty eye for range, speed , altitude and course. It also depended on his wetted finger held up for atmospheric conditions data (doesn't work to well on a moving destroyer). And depended on the aimer and trainers cartwheel sights for final aiming.
The 4.7s on the Os and Ps (those that had them) were hand worked and not power worked.
The were fitted with 4 single 20m as completed and were later changed (in most) to 2 singles and 2 twins for 6 barrels.
The Q and R classes did get the better "tribal" AA director set up but the guns were essentially unchanged from the H class if not earlier.
Of course if your really want to disagree with my assessment of the 4.7" guns as dual purpose you could always claim that the the 8" guns on the British cruisers were dual purpose because of their 70 degree elevation, of course they have that fixed loading angle down at 10 degrees that you complain about with the Japanese ships.
The Japanese also provided AA shells even for battleship guns but that doesn't really make them true AA guns or dual purpose does it?
The British early 4.7s may have been called dual purpose but they weren't even really fooling themselves about it.