N3-class battleship

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Class overview
NameN3
Operators Royal Navy
Preceded byRevenge class
Succeeded byNelson class
Planned4
Cancelled4
General characteristics
TypeBattleship
Displacementabout 48,500 long tons (49,300 t)
Length820 ft (249.9 m)
Beam106 ft (32.3 m)
Draught33 ft (10.1 m) (at
deep load
)
Installed power
Propulsion2 shafts; 2 geared steam turbine sets
Speed23 knots (43 km/h; 26 mph)
Armament
  • 3 × triple 18 in (457 mm) guns
  • 8 × twin 6 in (152 mm) guns
  • 6 × single 4.7 in (120 mm)
    AA guns
  • 4 × 10-barrel
    2-pdr (40 mm (1.6 in))
    AA guns
  • 2 × 24.5 in (622 mm) torpedo tubes
Armour

The N3 class was a

G3-class battlecruiser, but had larger guns and thicker armour. They were never ordered due to signing of the Washington Naval Treaty in 1922, which limited the size and armament of battleships to 35,000 long tons
(36,000 t) and guns no bigger than 16 inches (406 mm).

Background

In 1916 the US had declared its intention to create a Navy "second to none"; Congress had authorized the building of a large number of battleships and battlecruisers. In response, the Japanese government also began a large programme of warship building (

the 8-8 fleet). Two improved Revenge-class hulls were rebuilt into the two Renown-class battlecruisers by the Royal Navy during the war. The only new capital ships laid down during the war were the Admiral-class battlecruisers. Their design had been called into question after the Battle of Jutland in 1916 and three ships of this class were cancelled, leaving only HMS Hood to be completed to a modified design.[1]

The US plan had been delayed by the wartime need to build smaller vessels. Nevertheless, estimates by the Admiralty were that by the early 1920s the Royal Navy would be behind in ships.

G3-class battlecruisers to be built first, presumably to be followed by the same number of battleships the following year.[1]

A pair of designs were prepared in June 1920, derived from the "U-4" battleship design of 1914, of ships with displacements of about 50,000 long tons (51,000 t) and armed with eight or nine guns, in four twin or three triple

centre of gravity as low as possible[3] and avoid the extra weight required for tall, superfiring barbettes.[4]

The designs were revised in October and split into separate battleship and battlecruiser designs. The battleship designs were given letters of the alphabet from L through N, with the use of triple or double gun turrets shown by 3 or 2 respectively. Both 'L2' and 'L3' had superfiring guns and the armour was reduced to a 15-inch (381 mm) inclined

transom sterns. 'L2' displaced 52,100 long tons (52,900 t), but 'L3' was a thousand tons lighter. 'M2' and 'M3' followed in November and December and were very different from the earlier designs.[5]

'M2' and 'M3' sacrificed fire directly astern by moving the rear turret(s) amidships in order to save weight by shortening the length of the armoured citadel. Compared to the earlier, more conventional, designs, 'M2' saved 1,540 long tons (1,560 t) and 'M3' 1,740 long tons (1,770 t).[6] More weight was saved by reducing the designed speed to 23–23.5 knots (42.6–43.5 km/h; 26.5–27.0 mph) and using only two propeller shafts, although it was thought that this would improve manoeuvering power over four smaller propellers. These changes saved 4,350 long tons (4,420 t) for 'M2' and 5,000 long tons (5,100 t) for 'M3' over their predecessors. A lengthened version of 'M3' was chosen for further development as N3 and approved in November 1921.[7]

Description

Photo showing a battleship in the foreground and more battleships and cruisers in the background
Many of the aspects of the N3 design were incorporated into HMS Nelson, shown here.

Most noticeable of the N3 design was the concentration of the main battery forward of the bridge and machinery spaces. A related feature of the design was the tower bridge structure behind the first two gun turrets. This provided a better and more stable foundation for fire-control equipment, greatly improved accommodation and protection from the weather.[8]

The N3 battleships were significantly larger than their predecessors of the

double bottom 7 feet (2.1 m) deep.[9]

The ships would have had two geared

kW). The ships' maximum speed would have been about 23 knots.[10]

Housing the main armament in triple turrets was new to the Royal Navy though British companies had been involved in the production of triple-gun turret designs for other navies.

BL 15-inch Mark I gun of 42-calibre length which were lower-muzzle-velocity weapons firing heavy shells.[12]

Armament

The N3 design mounted nine 45-calibre

superfiring twin turrets. Four turrets were sited around the forward superstructure and four at the stern.[18] The guns could elevate between –5° and +60°. They fired 100-pound (45 kg) projectiles at a muzzle velocity of 2,945 ft/s (898 m/s). Their maximum range was 25,800 yd (23,600 m) at 45° elevation. Their rate of fire was five rounds per minute.[19]

An

QF 2-pounder gun (commonly known as a pom-pom), two abaft the funnels and two at the stern. Each barrel was provided with 1300 rounds of ammunition.[20] The gun fired a 40-millimetre (1.6 in) .91-pound (0.41 kg) shell at a muzzle velocity of 1,920 ft/s (590 m/s) to a distance of 3,800 yards (3,500 m). The gun's rate of fire was approximately 96–98 rounds per minute.[22]

Like previous classes of British battleships, a pair of submerged,

TNT and were powered by oxygen-enriched air. They had two speed settings which governed their range: either 15,000 yards (13,716 m) at 35 knots (65 km/h; 40 mph), or 20,000 yards (18,288 m) at 30 knots (56 km/h; 35 mph).[23]

Fire-control

The main guns of the battleships could be controlled from either of the two

mizzenmast.[24] Each pom-pom mount had its own director and there was also a height-finder aft. Two 15-foot (4.6 m) torpedo rangefinders were located on the sides of the funnels.[20]

Armour

A first for any British

reserve buoyancy to keep the ship stable even if the rest of the hull was riddled by gunfire.[25]

The waterline belt of the N3 had a maximum thickness of 15 inches (381 mm) thick with the top of the armour angled outward at 25°. This angle increased the armor's relative thickness to horizontal, close-range fire, albeit at the cost of reducing its relative height which increased the chance of plunging shellfire going over or under it. It ran some 463 feet (141.1 m), from 9 feet (2.7 m) forward of 'A' barbette to the rear of the after 6-inch magazine. For about 115 feet (35.1 m), it reduced to 13.5 inches (343 mm) over the engine and boiler rooms. The belt had a height of 14 feet 3 inches (4.3 m), of which 4 feet 6 inches (1.4 m) was below the designed waterline. The lower edge of the belt abreast the magazines was continued down another 3 feet (0.9 m) by a 4 inches (102 mm) thickness of high-tensile steel inclined at 36° to prevent a shell from reaching the magazines via a wave trough at high speed. The ends of the belt terminated in 14-inch (356 mm) transverse bulkheads.[26] The 8-inch (203 mm) armoured deck matched the length of the waterline belt and sloped down to meet the upper edge of the belt. It extended forward over the torpedo compartment which had a separate transverse bulkhead protecting it that was 9 inches (229 mm) thick. The steering gear was protected by a deck and bulkhead 6 inches (152 mm) thick.[17]

The turret faces were 18 inches (457 mm) thick while their sides were probably 14 inches (356 mm) in thickness, and the roof was 8 inches thick. The armour of the barbettes and the conning tower was 15 inches thick and the conning tower's communications tube to the upper deck was 8 inches thick. The fire-control director atop the conning tower was protected by an armoured hood 4 to 6 inches thick.[17]

The anti-torpedo bulges of the N3 were internal to the hull and were intended to withstand the explosion of a 750-pound (340 kg) torpedo warhead. They consisted of an outer air space, an inner buoyancy space and the 2 inches (51 mm) thick torpedo bulkhead. The bulkhead was situated about 16 feet (4.9 m) inboard from the side of the ship.[26] Postwar tests done on a replica of this system showed that filling the buoyancy space with water rather than the sealed steel crushing tubes as used in Hood was just as effective and weighed less.[27]

Cancellation

The four N3 battleships were never ordered because the Washington Naval Treaty, an arms limitation treaty under negotiation at the time, forbade construction of any ship larger than 35,000 tons. Many of the aspects of their design ultimately were incorporated into the two Nelson-class battleships, and they are often described as being a cut-down N3. Indeed, the Nelsons received the design designation 'O3', marking them as next in the design sequence, although they used the guns intended for the G3 battlecruisers for cost reasons and to comply with the Treaty's 16-inch limitation on main armament.[28]

Notes

  1. ^ The mounts were at a very early stage of development at this time and the number of barrels was reduced to eight before they went into production.[20]

Citations

  1. ^ a b c Campbell, Part 1, p. 4
  2. ^ Friedman, pp. 420, 446
  3. ^ Brown, pp. 172–173
  4. ^ Campbell, Part 2, p. 13
  5. ^ Raven and Roberts, p. 102
  6. ^ Brown, p. 174
  7. ^ Raven and Roberts, pp. 102, 105
  8. ^ Raven and Roberts, p. 127
  9. ^ Raven and Roberts, pp. 101, 105
  10. ^ Brown, pp. 174–175
  11. ^ Campbell, Part 1, p. 9
  12. ^ Campbell, Part 1, p. 7
  13. ^ Raven and Roberts, pp. 105–106
  14. ^ Campbell, Part 1, pp. 6–7
  15. ^ "British 18"/45 Mark II". Navweaps.com. 23 December 2006. Retrieved 10 November 2020.
  16. ^ "Japanese 46 cm (18.1")guns". Navweaps.com. 23 April 2007. Retrieved 10 November 2020.
  17. ^ a b c Raven and Roberts, p. 106
  18. ^ a b Raven and Roberts, p. 100
  19. ^ "British 6"/50 (15.2 cm) BL Mark XXII". Navweaps.com. 7 January 2007. Retrieved 26 July 2010.
  20. ^ a b c d e f Campbell, Part 3, p. 42
  21. ^ "British 4.7"/43 (12 cm) QF Mark VII 4.7"/40 (12 cm) QF Mark VIII 4.7"/40 (12 cm) QF Mark X". Navweaps.com. 31 December 2006. Retrieved 26 July 2010.
  22. ^ "Britain 2-pdr [4 cm/39 (1.575")] Mark VIII". Navweaps.com. 20 February 2008. Archived from the original on 26 June 2015. Retrieved 7 June 2010.
  23. ^ "British Torpedoes Pre-World War II: 24.5" (62.2 cm) Mark I". Navweaps.com. 12 January 2009. Retrieved 7 March 2010.
  24. ^ a b Raven and Roberts, pp. 100, 106
  25. ^ Raven and Roberts, p. 92
  26. ^ a b Campbell, Part 3, p. 43 and Part 4, p. 37
  27. ^ Raven and Roberts, p. 93
  28. ^ Campbell, Part 4, pp. 37–38

References

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