First dual-purpose armament

Markus,

You forgot HMS Vanguard, sunk by internal explosion at Scapa Flow on July 9, 1917, and SMS Viribus Unitis, sunk by Italian frogmen using limpet mines at Pola, November 1, 1918.

Also

Somehow, I don't think the crew of the SMS Pommern would consider the destroyer threat overrated...Well...If they HAD lived, I don't think they would have.

 

Refresh my memory again, are we still debating dual-purpose weapons, or just secondary batteries in general?

 

Thank you for reminding us of the subject of the thread. It is so easy to stray off track.

 

RN Leonardo da Vinci and the russian Imperatritsa Mariya were lost to magazine explosions in port as well, that's why I specified "combat". Viribus Unitis was sunk by "ante litteram" frogmen but I wouldn't count her as a war loss as her "ownership" at the time was uncertain. IIRC a single torpedo hit on HMS Marlborough eventually disabled her a Jutland so there was very little evidence of "inneffectiveness" of torpedoes.

Does anyone have more data on the design decision behind the high angle 8" on the Kents, were they a failed experiment ?
The Japanese destroyer 5" were also capable of HA fire but too slow in tracking for effective AA use, do we count them as DP?

 

AFAIK, the 8-inch guns were a failed experiment for both the British and Japan, for mostly the same reasons. Slow to elevate & train, low loading angles, weak elevation gears that needed to be strengthened; which in turn increase turret weight. IIRC, the British had many minor problems with their turret, while the Japanese had a few major problems with theirs.

Lacroix & Wells give the Japanese 8-inch excellent coverage in their book, and the County class mounts get some coverage in "Man o' War 1 - County Class Cruisers" by Alan Raven & John Roberts.


As to the Japanese 5-inch destroyer guns, I don't think I would. I was under the impression that the later mounts allowed for increased elevation to permit HA fire, but were essentially the same as their low-angle brethren. I never really looked into the details of the mount, since the books I have on them are in Japanese, which I don't read, but the books have excellent pictures & drawings for reference.

 

AFAIK the second group of "specials" 5" guns ("B" mount) could be independently elevated to 75 degrees but I can't find any AA directors on the early japanese DDs though the third group of the "specials" had a distinct torpedo FC. A.J. Watts credits the "B" mount with 70 degrees elevation and states the FC was DP as well, making them the first DP DDs 6 years before Porter and 10 before the British L class.. AFAIK the later Yugumo and Kagero classes had gun elevation limited to 55 degrees that still suggests a limited AA role but still no dedicated AA FC. We would need original Japanese sources to really understand what they were meant for.

 

Yes, I have run into the same problem regarding fire control on the Japanese 'Specials'. "Warship Profile 22" and "Warship Special 2" only briefly mention the fire control, offering little useful information on the subject. I have a copy of the Profile Morskie 24, but it is all in Polish(written before they started doing bilingual volumes).

I think you are wrong concerning the Porter class, they had four dual SP mounts and not DP. IIRC, the first DP mounts were singles 5-inch/38s on the Farragut class.

 

The Porter and Somers class leaders were unusual for US DDs in not having DP armament, which had been introduced in the Farragut class, 5"/38s with 85 degree elevation and Mark 33 gunfire control systems. I'm a bit puzzled about the leaders. Contemporary DDs like the Mahan class carried five 5"/38s and twelve torpedo tubes. The leaders were about 40 feet longer and 300 tons heavier; it seems like they ought to have been able to work in a sixth gun and maybe a second Mark 33, which would be a major improvement. Single 5" were considered to have a better rate of fire than twins, so there would be little difference in effective firepower even against surface targets. Incidentally the quad 1.1" mounted in the leaders do not appear to have been considered necessary in DP-armed ships, at least not until the much larger Fletcher class.

British destroyers introduced an AA gunfire control capability in the Tribal class, built into the Range Finder Director, but it was limited by the 40 degree elevation of the guns. The L and M classes had a different director and 50 degree mountings, a bit of an improvement but not truly DP IMO. The mass production War Emergency destroyers reverted to the previous arrangement with a variety of guns:

O (four ships) and P classes - single 4" Mark V AA guns, mostly removed from capital ships and cruisers refitted with Mark XIX twins.

O (four ships), Q and R classes - 4.7" in 40 degree mountings.

S, T, U, V, W classes - 4.7" in 55 degree mountings

Z, Ca, Ch, Co, Cr classes - 4.5" in 55" mountings, also new director systems and Remote Power Control in last three classes, most of which were completed postwar.

Four of the Ls were completed with four twin 4" mountings, the standard 80 degree Mark XIX, due to slow delivery of the complex twin 4.7s; this made them effective AA ships. Surviving Tribals received a Mark XIX in place of X mounting; the RFD had the interesting capability of generating gun orders for both this and the 4.7s, assuming the target was within the 40 degree limits of the latter.

 

I don't have Friedman handy, but IIRC, the Porters were intended to have six single DP 5-inch guns. However, it was found that they could carry eight 5-inchers, but in SP mounts. At the time, they US believed in the need for greater surface firepower to compensate for the larger destroyer types being built. While the difference in number of shells thrown was slight, it was seen as an increase.

 

My bad, took A.J.Watts reference to the Porter for good without double checking. I think for Britain the L (at least the 4" armed ones) is the first DP fleet destroyer class.

 

Well, the Porters did get the 5-inch/38s later on in the Pacific war, but I don't think any of them had all of the twin SP mounts replaced with twin DP mounts. IIRC, the "standard" fit, after removal of all SP mounts, was two twin DP mounts(located fore and aft) and one single DP mount(located aft). The same applied to the Somers class.

 

Looking at
USA 5"/25 (12.7 cm) Marks 10, 11, 13 and 17
and
USA 5"/38 (12.7 cm) Mark 12
The 5"38 has a slightly heavier projectile fired at a higher significantly higher velocity. Should be much better in both surface and AA.

 

The original scheme for rearming the leaders was six DP 5"/38s, single mounts superfiring over twins fore and aft. These were fully enclosed mounts, as were the original ones, so this provides a useful illustration of the "cost" of the DP feature. Subsequently it was decided to replace* the single mount forward with a 40mm; quad in the Porters and twin in the more topweight-critical Somers. The centerline position forward was an excellent one for a 40mm and the refitted leaders were the only US DDs to have it.

Which reminds me of the Sumner and Gearing classes. I think they would have been better off with a quad 40mm in #2 position forward and #2 5" mount on the 01 level aft where, for some reason, a position with almost unrestricted sky arcs was devoted to - torpedo tubes. This would also have reduced topweight - due to the deck sheer the 01 level aft was almost a deck level lower than forward - and the reduced weight forward would help their seakeeping.

* happened to look back at this and noticed a needed clarification; the 'replacement' was decided while the rearmament was being designed, none actually mounted the single 5" forward.

 

I'll say this. The 5"38 seemed to have a better and more dependable gun mount system even in the MK28 Mod2 turrets than the 5"54 guns ever had. The 38 was a work horse and a joy to to have shoot for you. 54's faster but prone to gun mount casualties.