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RN AAcruiser

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Using heavy cruiser to anti other cruisers, light cruiser to anti destorys, air defense cruiser to anti aircraft is not cost-effective. The general cruiser is coming out . In the history of the RN, there is a tradition of the main ship with light main gun and heavy auxiliary gun. Based on the Exeter, the project 131 of Spain is a suitable model. We can strengthen the dual-purpose gun from 120 to133 , which can take into account three mission requirements.
 

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Sherman Tank

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Who is "we"? And what evidence do you have that anything besides the Neptune/Minotaur and stolen Tzoli pictures you posted are real vessels?
 

Volkodav

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Is this the 5.25" cruiser Cunningham killed off in favour of 6" studies?
 

Tzoli

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Who is "we"? And what evidence do you have that anything besides the Neptune/Minotaur and stolen Tzoli pictures you posted are real vessels?
You do know I am here right?

While indeed I wasn't exactly asked for it to be shared BUT!!! I DO NOT MIND at all because it is my drawing and contains my signature which did not removed hence shows it is mine.

as for sources:
Norman Friedman - British Cruisers: Two World War and After
Norman Friedman - The Postwar Naval Revolution
Alan Raven, John Roberts - British Cruisers of World War Two
David K. Brown, George Moore - Rebuilding the Royal Navy: Warship Design Since 1945

some sketches from the books:
1592036002152.png

1592036035207.png

1592035743366.png
 

DWG

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The K25 series was not so much for an AA cruiser, but for a general purpose cruiser that happened to be AA capable - which also describes the intended role of the Didos, and similarly the intended flotilla leader role of the US Atlantas. For looks I prefer K25G with the four forward turrets all superfiring (and K25G* went right through to the final selection by the Admiralty Board, with Henderson as Controller throwing his weight behind it over K31, the final 6" design on offer), but the top-weight penalty would have been fearsome.
 

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I think topweight might be a lesser problem on these designs as they only carry a pair of turrets more then a Dido yet on a larger hull
 

DWG

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I think topweight might be a lesser problem on these designs as they only carry a pair of turrets more then a Dido yet on a larger hull
You're right that the larger hull would help, but the problem is not just the weight of the turrets, but their height - the significant factor is their moment arm, so it's weight times height above the waterline. And it isn't just the turrets we have to consider, the fourth superfiring forward turret pushes the bridge and everything above it up at least one deck level compared to the earlier K25 designs with four turrets on three levels. There's a similar effect at the stern, but here it's only the aft director (still a substantial weight) being pushed up a deck level compared to the earlier designs.
 

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I've made some calculations based on the data from the navweaps site.
I don't know if on that site turret weight includes the guns themselves or not but I got these numbers:

6" BL Mark XXIII Guns:
7tons each
12x7=84tons total
turret weight used by the Crown Colony Class:
161tons each
4x161=644tons
together: 728tons

5,25" QF Mark I Guns
4,36tons each
14x4,36=61tons total
turret weight based on the Dido Class:
85-98tons each
7x85-98=595-686tons
together: 656-747tons
 
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Volkodav

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These studies were on what became the Crown Colony Class and the Dido was evolved from the Arethusa, where there any 5.25" AA cruiser studies with the Leader or Modified Leander as the starting point? I don't recall ever seeing any but was wondering if any of you who have had access to source documents may have come across something?
 

Tzoli

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The Leander class was not used for such studies.
The 5,25" Cruiser designs post Dido were the Emergency cruiser design from 1951, a modified Dido with 4 twin 5,25, and 3 twin Bofors 40mm with 6 twin 20mm Oerlikons
There was an 1936 project for a minelayer cruiser with 3 twin 5,25.
The Hawkins conversion project of 1938 with 6 twin 5,25
A Number of Crown Colony preliminaries of 1936 with mostly 7 twin mounts though there was one with 6 and another with 8 mounts
Vickers offered a design in 1936 with 8 twin mounts on a somewhat smaller smaller hull then the Crown Colony
Later an offer for Chile in 1939 for an export version of the Dido with 4 twin mounts (Design 1111)
some time later the same armament appeared on the 1940 design 1122 again an export version of the Dido
AA Cruiser Design K for the RN in 1940 offered only 3 twin mounts
In 1944 DNC offered a Cruiser for Australia with 4 triple turrets
Vickers offered Venezuela in 1945 again an export Dido variant with 4 twin mounts

And of course the secondary turrets on the KGV, Lion and Vanguard preliminaries as well as for the proposed modernizations of the Hood and Nelson classes.
These were the Mark I Guns

With the newer project of Mark IV guns:
there were a number of Neptune preliminaries of 1942 with 3,5 and even with 6 twin mounts or 3 and 4 triples.
Design N1 and N2 of 1943 with 4 twin mounts

Interestingly I've never seen a design with single 5,25" mounts or turrets say for a small cruiser or destroyer. (I did see once ages ago a hypothetical carrier model with single 5,25" turrets basically cut in half assymetrical Dido turrets)
 

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Interestingly I've never seen a design with single 5,25" mounts or turrets say for a small cruiser or destroyer. (I did see once ages ago a hypothetical carrier model with single 5,25" turrets basically cut in half assymetrical Dido turrets)
ISTR the shore-based AA/Coastal defence mounts were singles.
 

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Yes but these are different and we are interested in ships :)
 

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Most were singles but 3 spare twin mounts were installed around London as AA batteries. Some singles still survive in Gibraltar.
 

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You're right that the larger hull would help, but the problem is not just the weight of the turrets, but their height - the significant factor is their moment arm, so it's weight times height above the waterline.
Strictly speaking it's height above the centre of buoyancy that matters, which is why weight close to the waterline still causes stability problems.

The centre of buoyancy is generally one-third to half the draught below the waterline, but that's a function of the hullform. As is the location of the metacentre, which is also calculated with respect to the centre of buoyancy. Keep the centre of gravity well below the metacentre or else you'll have a bad day at sea!

Because the shape of the immersed hull changes with displacement, weird things can happen sometimes. I've dealt with a barge loading condition where adding topweight actually improved stability by increasing the displaced volume significantly. But that isn't normal, and adding the same weight low down would have an even more beneficial effect.
 

EwenS

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The 5.25" Colony designs also take out the 4" Mk.XIX mounts of 16-18 tons each at main deck level, while there will be a very small compensation by moving the pom-poms from tha hangar deck to the main deck.
 
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DWG

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Strictly speaking it's height above the centre of buoyancy that matters, which is why weight close to the waterline still causes stability problems.

The centre of buoyancy is generally one-third to half the draught below the waterline, but that's a function of the hullform. As is the location of the metacentre, which is also calculated with respect to the centre of buoyancy. Keep the centre of gravity well below the metacentre or else you'll have a bad day at sea!

Because the shape of the immersed hull changes with displacement, weird things can happen sometimes. I've dealt with a barge loading condition where adding topweight actually improved stability by increasing the displaced volume significantly. But that isn't normal, and adding the same weight low down would have an even more beneficial effect.
I couldn't remember metacentric height when I needed it, so went with waterline as sufficient to get the point across. But the actual detail makes the point even better.
 

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I've just re-read the Forum rules and noticed that reopening topics with further info is OK. As the latest posts on here are 2010 and 2011, I did write an article for "Warship" 2010, page 43 (AA to AA - the Fijis turn full circle) which discussed the Fijis in detail with emphasis on the various AA variants from the K25's to the Tigers, and various emergency versions between. In it were drawings of all the Fiji preliminary designs, including the K25 AA versions by John Jordan based on Admiralty sketch design drawings. N2, the 1944 AA cruiser got a description as a footnote, but no drawing. There are drawings of N2 in George Moore's book "Building for Victory" though the automatic MkIII rectangular turrets he portrays were not available for a 1944 design, and I don't think he sticks very closely to the written description of "two funnels set close together roughly where the second turret stands" (on Royalist). There are drawings of an earlier automatic twin 5.25 in the Vickers archive in the Brrow library, which looked more like the curved top Mk I and II. I covered Dido's origins in an article on RN interwar small cruisers (Damnable Folly) in Warship 2011, p.130. Scylla and Charybdis had 4x2 4.5in to meet shortages of 5.25s
[D. Murfin]
 

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@smurf, it’s wonderful to see you posting here again. Thanks for the insight and welcome back, I hope you are well.
 
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