USN decision 1937

[chuck]

After much experimentation, the USN found a combination of 4 major directors and multiple blind-fire radar (Gunar) would defeat any threat from any directon, even straight-on or from astern.

It could direct fire towards threat from any direction. There is no guaranty of defeating threats from any direction

[phil gollin]

So many factors not mentioned.

In general (very, very general) the larger the ship the more stable a gun platform and the better the performance from the "same" systems.

Electronic and passive jamming of radars could cause a severe drop in performance.

WW2 era VT fuzes had much better performance against directly approaching targets than crossing targets.

Separate directors for bofors/pom-poms were excellent.

.

[Werner]

The USN rule of thumb is 4 40mm quads for any 180 degree opposed arc for self-defense. The count of 20mm is really dependent on the deck space and size of the crew, so in a larger ship these will prosper. Neither of these weapons are of much use beyond a mile or so. For that you need an AAA director. The argument swayed between 2-4 directors for some time, with Des Moines bearing the weight of the debate. When the Kamikaze threat materialized. the issue was settled in favor of a minimum of 4 directors on cruisers and larger ships (Note: even Essex was designed for 3-4 Mk.37 directors.

The Mk.37 system and it's computers, stable elements and predictors was so far superior to any device 1939-1945 that it was specified for HMS Vanguard. The corresponding British system was much heavier and not able to deal with targets flying as fast as could the Mk.37

[Tracy White]

(Note: even Essex was designed for 3-4 Mk.37 directors.

3 max for the class, only on the long hulls, and only two were ever mounted, even on the long hulls.

[SumGui]

Preliminary design was not finished for Atlanta (CLAA) until June 1938, and the first ships were ordered 25 Apr 1939.

(Source: US Cruisers, and Illustrated Design History, Norman Friedman, Chp 8 pgs 233-240)

So, CLAA's were not yet availible in 1937.

I'd have built the bejesus out of Essex, Cleveland (with Atlanta dedicated to CV group escort), Gato and the almighty Fletcher abover all other classes, given the choice.

[Werner]

Quite so, but the General Board had prepared general characteristics for a range of ships from large independent cruisers to fleet support units in the early Thirties. One limitation of Friedman's design books is they are based to some degree on the correspondence and private memos of Captain Chantry, who was between the General Board and detail design at C&R. That's why Chantry's "Ironsides" design gets any mention and why it is linked (however implausibly) to the BB-57 design, which is, after all, a straightforward development of BB-55 with higher power and more armor to bring the design back into line with the initial specification for any USN battleship.

Higher power made available via capitalism, and not some unique sacrifice of internal arrangements like the Japanese.