Ordnance BL 8 inch gun Mk VIII
Forward 8-inch turrets aboard HMAS Canberra
TypeNaval gun
Coast defence gun
Place of originUnited Kingdom
Service history
In service1927 – 1954[1]
Used byRoyal Navy
Royal Australian Navy
Spanish Navy
WarsSecond World War
Spanish Civil War
Production history
No. built168[2]
Specifications
Mass17.5 tonnes[2]
Barrel length400 inches/10 meters(50 calibres)[2]
Shell256 pounds (116 kg)
Calibre8-inch (203 mm)[2]
Muzzle velocity2805 feet per second (855 m/s)[2]
Maximum firing range28 kilometres (17 mi)[2]

The BL 8 inch gun Mark VIII[note 1] was the main battery gun used on the Royal Navy's County-class cruisers,[note 2] 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 (203 mm) 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.[3] 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.[4]

Description

These guns, 50 calibres long, were built-up guns which 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 lb) of cordite were used to fire a 116 kg (256 lb) 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 version of the Mark II turrets with a maximum elevation of 50 degrees were installed in the '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.[5]

Coast defence guns

Gun of 428 Battery Coast Defence Artillery firing at dusk during World War II

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]

Ammunition

Shell trajectory

Range with 256 lbs. (116.1) SAPC with MV = 2,725 fps (831 mps)

Range[2] Elevation Time of flight Descent Impact velocity
5,000 yd (4,570 m) 2° 11′ 6 s 2° 31′ 2154 ft/s (657 m/s)
10,000 yd (9,140 m) 5° 14′ 14 s 7° 15′ 1683 ft/s (513 m/s)
15,000 yd (13,720 m) 9° 47′ 25 s 15° 49′ 1322 ft/s (403 m/s)
20,000 yd (18,290 m) 16° 34′ 38 s 28° 31′ 1169 ft/s (356 m/s)
25,000 yd (22,860 m) 26° 44′ 56 s 43° 7′ 1164 ft/s (355 m/s)
29,000 yd (26,520 m) 41° 28′ 79 s 56° 37′ 1240 ft/s (378 m/s)

See also

Weapons of comparable role, performance and era

Surviving examples

Notes

  1. ^ Mark VIII = Mark 8. Britain used Roman numerals to denote Marks (models) of ordnance until after World War II. Hence this was the eighth model of BL 8-inch naval gun.
  2. ^ 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".

References

  1. ^ Whitley 1995 pp.17,83&89
  2. ^ a b c d e f g h i j Campbell 1985 pp.31–33
  3. ^ Campbell 1985 p.389
  4. ^ Whitley 1995 pp.96–127
  5. ^ Lenton & Colledge 1968 pp. 36–39

Bibliography

External links

Wikimedia Commons has media related to BL 8 inch Mk VIII naval gun.
British Commonwealth naval weapons of the Second World War
British Commonwealth artillery of World War II
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