BL 8 inch Mk VIII naval gun

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Ordnance BL 8 inch gun Mk VIII
300px
Mk VIII guns in X and Y Mk I turrets aboard HMS Kent
Type Naval gun
Coast defence gun
Place of origin United Kingdom
Service history
In service 1927 - 1954[1]
Used by 22x20px Royal Navy
22x20px Royal Australian Navy
Wars Second World War
Production history
Number built 168[2]
Specifications
Weight 17.5 tonnes[2]
Barrel length 400 inches (10 meters)[2]

Shell 256 pounds (116 kg)
Calibre 8-inch (203 mm)[2]
Muzzle velocity 2805 feet per second (855 m/s)[2]
Maximum range 28 kilometres (17 mi)[2]

The 50 calibre BL 8 inch gun Mark VIII was the main battery gun used on the Royal Navy's County-class heavy cruisers[3], in compliance with the Washington Naval Treaty of 1922. This treaty allowed ships of not more than 10,000 tons standard displacement and with guns no larger than 8 inches to be excluded from total tonnage limitations on a nation's capital ships. The 10,000 ton limit was a major factor in design decisions such as turrets and gun mountings. A similar gun formed the main battery of Spanish Canarias-class cruisers.[4] In 1930, the Royal Navy adopted the BL 6 inch Mk XXIII naval gun as the standard cruiser main battery in preference to this 8-inch gun.[5]

Description

These built-up guns consisted of a wire-wound tube encased within a second tube and jacket with a Welin breech block and hydraulic or hand-operated Asbury mechanism. Two cloth bags each containing 15 kg (33 pounds) of cordite were used to fire a 116-kg (256-pound) projectile. Mark I turrets allowed gun elevation to 70 degrees to fire high-explosive shells against aircraft. Hydraulic pumps proved incapable of providing sufficient train and elevation speed to follow contemporary aircraft; so simplified Mark II turrets with a maximum elevation of 50 degrees were installed in the Norfolk subgroup ships Dorsetshire and Norfolk and the York-class cruisers York and Exeter. Each gun could fire approximately five rounds per minute. Useful life expectancy was 550 effective full charges (EFC) per barrel.[2]

Naval service

The following ships mounted Mk VIII guns in 188-tonne twin turrets.[2] The standard main battery was four turrets, but Exeter and York carried only three to reduce weight and formed the separate York class.[6]

Ammunition

Shell trajectory

Range[2] Elevation Time of flight Descent Impact velocity
5000 yd (4.6 km) 2° 11′ 6 sec 2° 31′ 2154 ft/s (657 m/s)
10000 yd (9.1 km) 5° 14′ 14 sec 7° 15′ 1683 ft/s (513 m/s)
15000 yd (14 km) 9° 47′ 25 sec 15° 49′ 1322 ft/s (403 m/s)
20000 yd (18 km) 16° 34′ 38 sec 28° 31′ 1169 ft/s (356 m/s)
25000 yd (23 km) 26° 44′ 56 sec 43° 7′ 1164 ft/s (355 m/s)
29000 yd (27 km) 41° 28′ 79 sec 56° 37′ 1240 ft/s (378 m/s)

Coast defence guns

Six single guns capable of elevating to 70 degrees were installed as coastal artillery in the Folkestone-Dover area during the Second World War.[2]

See also

Notes

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References

  • Campbell, John (1985). Naval Weapons of World War Two. Naval Institute Press. ISBN 0-87021-459-4. 
  • Lenton, H.T. & Colledge, J.J (1968). British and Dominion Warships of World War Two. Doubleday and Company. 
  • Whitley, M.J. (1995). Cruisers of World War Two. Brockhampton Press. ISBN 1-86019-8740. 

External links

Template:WWIIBritishCommNavalWeapons
  1. Whitley 1995 pp.17,83&89
  2. 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 Campbell 1985 pp.31-33
  3. A more accurate term is "Treaty Cruiser", as the term heavy cruiser was only formally defined at the time of the London Naval Treaty of 1930. However, all the 8-inch gun cruisers introduced as a result of the 1922 Washington Treaty were what became known as "heavy cruisers".
  4. Campbell 1985 p.389
  5. Whitley 1995 pp.96-127
  6. Lenton & Colledge 1968 pp.36-39