The RN post WW2 Gun development Programmes

[Tzoli]

We know that after WW2 the RN started developing new gun systems to combat the new generation aircrafts the jet planes and eventually missiles. This led to the 3"/70 QF Mark N1 and the 6"/50 QF Mark N5 guns which were adopted but also others like the Bofors 40mm/70 gun which was considered but eventually not adopted, the Vickers 4"/62 Mark Q Export gun and the abortive weapon systems like the 5"/62 and 5"/70 QF Mark N1 and 5"/56 QF Mark N2 as well as the 5,25"/50 QF Mark IV guns on which you can find some info here:

Britain Experimental 5" (12.7 cm) and 5.1" (13 cm) QF Guns - NavWeaps

www.navweaps.com

United Kingdom / Britain 6"/50 (15.2 cm) QF Mark N5 - NavWeaps

www.navweaps.com

Britain 3"/70 (7.62 cm) Mark 6 - NavWeaps

www.navweaps.com

Chile 4"/62 (10.2 cm) Vickers Mark Q - NavWeaps

www.navweaps.com

I think we can gather here all these weapon systems and proposed mountings.
So let me start with two:

A 6"/50 and 3"/70 Quad mountings intended for some of the Minotaur class cruisers (The British Worcesters) and an even more radical one a 16 barrel!!! 40mm likely Bofors mounting, mentioned in Norman Friedman's British Cruisers Two World Wars and After:

Page 268:

DNO was scrambling to produce higher and higher races of fire, because fast new aircraft (and missiles even more so) had to be destroyed so quickly. Thus in 1947 he proposed a quadruple 3in gun, and previously a sixteen-barrel Bofors had been considered as an alternative to the 3in. All of these weapons were massive, and they pushed up ship size. DNC produced a new series of designs, P, Q, Rand S, with five, four, or three twin 6in, with varying numbers of 3in, and with and without torpedoes.

And page 373:

Presumably the much greater weight of ammunition in the US triple could be attributed to the use of cased rather than bagged ammunition. The British shell was also lighter (112lbs rather than 130lbs). DNO pointed out that the new US twin DP mount was heavier than the triple mount in the Defence class (Mk 24). There were dramatic differences in design. The US triple carried all three guns in one sleeve, only 4ft 4in apart. DNO had recently investigated a plan for a quadruple 6in gun (which apparently did not appear in contemporary cruiser designs) with guns paired in two cradles. Trials suggested that the minimum distance guns had to kept apart so as not to interfere with each ocher was 6ft (similar trials were carried our before designing the triple turrets for the Nelsons). Alternatively, firing could be delayed; the British delayed the centre gun, the US Navy the two wing guns. American practice was being reviewed to see whether the minimum distance was excessive. In any case, using a common cradle made it impossible to correct for the muzzle velocities of individual guns, increasing the spread of the turret; and the failure of one gun could put the turret out of action. However, the common cradle made for a smaller roller path and saved one or two men as gunlayers, and allowed one or two machines to be omitted. DNO noted chat the American dual-purpose twin mount had independent guns.

GE Moore, 'Post-War Cruiser Designs for the Royal Navy 1946- 1956', in J Jordan (ed), Warship 2006 (Conway Maritime Press, London: 2006). The basic design (D) was the Minotaur chosen the previous year: five twin 6in, eight twin 3in, 645ft (wl), 18,380 tons. The difference in tonnage was that this time deep load rather than standard displacement was used. Alternative P showed that substituting quads for twin 3in and removing one twin 6in required another 15ft of length and an increase to 19,250 cons. Eliminating torpedoes saved 25ft (length 635ft) and reduced displacement to 18,500 tons, about that of Minotaur. Alternative Q was a step further up, another twin 6in being replaced by two quad 3in (total eight mountings): 675ft, 19,750 tons (or, without torpedoes, 665ft, 19,550 tons). Alternative R showed what happened if all the 6in were restored and eight quad 3in demanded: 710ft, 21,000 tons (without torpedoes, 700ft, 20,500 tons). Alternative S showed that cutting back to four quad mountings but demanding all five twin 6in would cost 660ft and 19,250 tons (without torpedoes, 660ft, 19,000 tons, presumably because the 3in guns did not interfere with the torpedoes, so no extra length was involved). A series of alternatives with eight or four twin 3in was appended, R1 of the series corresponding to Minotaur but larger: 660ft, 19,500 tons.

I wonder if anybody heard about these quad 3" and 6" mountings as well as the 16 barrel 40mm one?

 

[A Tentative Fleet Plan]

Vickers Mark Q was a private venture export design, not related to any Royal Navy Programs.

The was a 4" Mark 25 DEMS (Defensively Equipped Merchant Ships) gun fro merchant ships and the Type 42 East Coast Gunboat. Friedman says it was related to the Mark Q, Peter Marland says otherwise.