BL 8 inch Mk VIII naval gun
Encyclopedia
The 50 calibre BL 8 inch gun Mark VIII was the main battery gun used on the Royal Navy
's County-class
heavy cruiser
s, 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 ship
s. 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. 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.
s 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 and and the York-class
cruisers and . Each gun could fire approximately five rounds per minute. Useful life expectancy was 550 effective full charges (EFC) per barrel.
.
in the Folkestone
-Dover
area during the Second World War.
Royal Navy
The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...
's County-class
County class cruiser
The County class was a class of heavy cruisers built for the British Royal Navy in the years between the First and Second World Wars. They were the first post-war cruiser construction for the Royal Navy and were designed within the limits of the Washington Naval Conference of 1922...
heavy cruiser
Heavy cruiser
The heavy cruiser was a type of cruiser, a naval warship designed for long range, high speed and an armament of naval guns roughly 203mm calibre . The heavy cruiser can be seen as a lineage of ship design from 1915 until 1945, although the term 'heavy cruiser' only came into formal use in 1930...
s, in compliance with the Washington Naval Treaty
Washington Naval Treaty
The Washington Naval Treaty, also known as the Five-Power Treaty, was an attempt to cap and limit, and "prevent 'further' costly escalation" of the naval arms race that had begun after World War I between various International powers, each of which had significant naval fleets. The treaty was...
of 1922. This treaty allowed ships of not more than 10,000 tons standard displacement
Displacement (ship)
A ship's displacement is its weight at any given time, generally expressed in metric tons or long tons. The term is often used to mean the ship's weight when it is loaded to its maximum capacity. A number of synonymous terms exist for this maximum weight, such as loaded displacement, full load...
and with guns no larger than 8 inches to be excluded from total tonnage limitations on a nation's capital ship
Capital ship
The capital ships of a navy are its most important warships; they generally possess the heaviest firepower and armor and are traditionally much larger than other naval vessels...
s. 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
Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...
Canarias-class
Canarias class Cruiser
The Canarias class was a class of heavy cruiser of the Spanish Navy. Two ships of the class were completed in the 1930s. They were designed in the United Kingdom and were modified versions of the Royal Navy's County class cruiser. They were built in Spain by the Vickers-Armstrongs subsidiary...
cruisers. In 1930, the Royal Navy adopted the BL 6 inch Mk XXIII naval gun
BL 6 inch Mk XXIII naval gun
The 50 calibre BL 6 inch gun Mark XXIII was the main battery gun used on the Royal Navy's conventional light cruisers built from 1930 through the Second World War.-Description:...
as the standard cruiser main battery in preference to this 8-inch gun.
Description
These built-up gunBuilt-up gun
The term built-up gun describes a construction technique for artillery barrels. An inner tube of metal which stretches most within its elastic limit enlarges under the pressure of confined powder gases to transmit stress to outer cylinders under tension...
s consisted of a wire-wound tube encased within a second tube and jacket with a Welin breech block
Welin breech block
The Welin breech block was a revolutionary stepped, interrupted thread design for locking artillery breeches, invented by Axel Welin in 1889 or 1890...
and hydraulic or hand-operated Asbury mechanism. Two cloth bags each containing 15 kg (33 pounds) of cordite
Cordite
Cordite is a family of smokeless propellants developed and produced in the United Kingdom from 1889 to replace gunpowder as a military propellant. Like gunpowder, cordite is classified as a low explosive because of its slow burning rates and consequently low brisance...
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 and and the York-class
York class cruiser
The York class was the second and last class of gunned cruisers built for the Royal Navy under the terms of the Washington Naval Treaty of 1922. They were essentially a reduced version of the preceding County class, scaled down in an effort to extract more, smaller ships from the treaty limits...
cruisers and . Each gun could fire approximately five rounds per minute. Useful life expectancy was 550 effective full charges (EFC) per barrel.
Naval service
The following ships mounted Mk VIII guns in 188-tonne twin turrets. The standard main battery was four turrets, but Exeter and York carried only three to reduce weight and formed the separate York classYork class cruiser
The York class was the second and last class of gunned cruisers built for the Royal Navy under the terms of the Washington Naval Treaty of 1922. They were essentially a reduced version of the preceding County class, scaled down in an effort to extract more, smaller ships from the treaty limits...
.
- County-class heavy cruisersCounty class cruiserThe County class was a class of heavy cruisers built for the British Royal Navy in the years between the First and Second World Wars. They were the first post-war cruiser construction for the Royal Navy and were designed within the limits of the Washington Naval Conference of 1922...
: 14 ships - York-class heavy cruisersYork class cruiserThe York class was the second and last class of gunned cruisers built for the Royal Navy under the terms of the Washington Naval Treaty of 1922. They were essentially a reduced version of the preceding County class, scaled down in an effort to extract more, smaller ships from the treaty limits...
: 2 ships
Shell trajectory
| Range | 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 artilleryCoastal artillery
Coastal artillery is the branch of armed forces concerned with operating anti-ship artillery or fixed gun batteries in coastal fortifications....
in the Folkestone
Folkestone
Folkestone is the principal town in the Shepway District of Kent, England. Its original site was in a valley in the sea cliffs and it developed through fishing and its closeness to the Continent as a landing place and trading port. The coming of the railways, the building of a ferry port, and its...
-Dover
Dover
Dover is a town and major ferry port in the home county of Kent, in South East England. It faces France across the narrowest part of the English Channel, and lies south-east of Canterbury; east of Kent's administrative capital Maidstone; and north-east along the coastline from Dungeness and Hastings...
area during the Second World War.
See also
- 203mm/50 Modèle 1924 gun203mm/50 Modèle 1924 gunThe 203mm/50 Modèle 1924 was a medium naval gun of the French Navy.The type was used on the Duquesne and Suffren classes of heavy cruisers as main battery, mounted in four twin turrets weighing 180 tonnes each...
French equivalent - 20.3 cm SK C/34 Naval gun20.3 cm SK C/34 naval gunThe 20.3 cm SK C/34 naval gun was the main battery gun used on all German World War II heavy cruisers.-Description:These built-up guns consisted of a rifled tube encased within an inner and outer jacket with a horizontal sliding breech block. The breech was sealed with an 18 kg brass case...
German equivalent - 203 mm /53 Italian naval gun203 mm /53 Italian naval gunThe 203 mm/53 Ansaldo was the main battery gun of Italy's most modern Washington Naval Treaty heavy cruisers. 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...
Italian equivalent - 20 cm/50 3rd Year Type naval gun20 cm/50 3rd Year Type naval gunThird year type 20 cm/50 caliber guns formed the main battery of Japan's World War II heavy cruisers. These guns were also mounted on two early aircraft carriers...
Japanese equivalent - 8"/55 caliber gun8"/55 caliber gunThe 8"/55 caliber gun formed the main battery of United States Navy heavy cruisers and two early aircraft carriers...
US equivalent
Surviving examples
- A gun from HMAS Australia outside the Australian War MemorialAustralian War MemorialThe Australian War Memorial is Australia's national memorial to the members of all its armed forces and supporting organisations who have died or participated in the wars of the Commonwealth of Australia...
, Canberra
External links
- Tony DiGiulian, Britain 8"/50 (20.3 cm) Mark VIII