Francis Marliere wrote:
dunmunro wrote:Which of Friedman's books are you referring to? I disagree that the Tribal's AA director was worse. It was a very lightweight director that could track targets easily versus Mk 33 which was a nightmare to use against aircraft
I refer - from memory since I don't have the book at hand - to "Naval antiaircraft guns and gunnery". The book is highly critical of British AA directors and also states that while the Mk 37 turned into a very efficient system when fitted with radars and proximity fuzes, the Mk 33 was not a success. However
dunmunro wrote:This allowed for 8 x 4.7in guns with AA capability in the Tribals, 6 x 4.7in/50 (50 deg elevation) in the L-M class and 6 x 4.7in in the J-K-Ms versus no 5in AA capability in the USN leaders and only 4 x 5in with AA capability guns in the smaller destroyer classes that were equivalent to the J-K-M class
The 4.7" guns had a short engagement envelope, and as AA escorts usually had to fire and umbrella barrage over the target, which was not - still from Friedman's book - not very effective.
It seems that you prise British guns more than the British did. They were more than aware of the limitation of their guns against aircrafts and shifted later on the war to 4.5" guns (why change your guns if they just work fine ?). IMHO 4.7" guns were more SP guns with a secondary AA capacity than a true DP gun (only the US 5"/38 was a true DP gun). I do not mean that British were stupids or incompetents : they just did not have the money build true DP guns and destroyers big enough to accomodate them (a DD with 8 DP guns would far bigger and more expensive than a Tribal). The RN had to do his best with the ressources available and IMHO made the good choice. The RN needed a lot of ships : I think that if the Brits build in the late 30s DD with true DP guns, there would be too few of them for fleet action and ASW.
Yes, Friedman is highly critical of RN directors and FC. Unfortunately, Friedman doesn't take the same critical analysis and apply it to USN systems. The Mk 33 and earlier systems were the USN's primary AA GFCS in service in 1939. The first Mk 37 didn't enter service until 1940 and even by mid 1941 Mk 37 was still quite rare so comparing a Tribal class, which entered service in 1938 to a USN destroyer that appeared several years later is a bit misleading. The USN had the luxury of continuing their AA GFCS development under peacetime conditions until Dec 1941, when the RN suddenly faced severe competition for access to the UK's industrial resources from Sept 1939 onward, and even more severely from mid 1940 onward.
The engagement envelop of a twin 4.7in/40 was limited by it's elevation and by the 25 sec max fuze time of the early MT fuzes, where the 5in/38 single was limited also by a 25sec max fuze timing in 1942. Against a 15000ft to (although at 15000ft the target would rapidly fly over the envelope) 12000ft altitude target both guns would open fire at aprox the same range, and against 9000ft altitude targets (as attacked Force Z) both guns would have approximately the same effective firing envelope, if the destroyer was acting as an AA escort. The effective AA envelope of a L-M class destroyer acting as an AA escort, with the 4.7in/50 was almost identical to a USN MK 37 destroyer.
The RN was aware of the limitations of gunfire against aircraft since they assessed their own claims very severely, but the USN BuOrd willfully ignored their own drone tests and then falsified their 1942 AA claims to produce fantastically optimistic kill numbers which, in turn, seemed to add validity to the money spent on Mk33/37 development. Mk 33/37 seemed fantastic, on paper, but in actual combat it's kill numbers per round fired were no better than the RN's - but this is something that Friedman rather disappointingly ignores. It wasn't until civilian scientists got involved in developing USN AA FC that some sane numbers began to be developed for the true efficacy of Mk 37. The RN claimed only 22 AA kills during the Battle for Crete, while BuOrd accepted USN Carrier TG claims for 37 during Coral Sea. At first glance it appears as though USN AA must have been far superior, yet post war analysis shows 15+ AA kills for the RN at Crete and only 3 for the USN at Coral Sea! This data was available to Friedman yet he opted not to use it...
Again, remember that the USN also the built the destroyer leaders that had 8 x 5in/38 but with no 5in/38 AA capability beyond simple barrage fire.