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| Ordnance BL 9.2 inch gun Mk I - Mk VII | |
|---|---|
 This gun fired the Jubilee Shot to a distance of 21,203 yards in 1887 to celebrate Queen Victoria's Golden Jubilee |
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| Type | Naval gun Coast defence gun |
| Place of origin | United Kingdom |
| Service history | |
| In service | 1881 - 1918 |
| Used by | Royal Navy |
| Wars | World War I |
| Production history | |
| Variants | Mk I - VII |
| Specifications | |
| Weight | Mk III : 24 tons barrel & breech; Mk V - VII : 22 tons1 |
| Barrel length | 290 inches (7,366 mm); (31.5 calibres)1 |
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| Shell | 380 pounds (172.37 kg)1 290 pounds (131.54 kg) (High-angle guns)2 |
| Calibre | 9.2-inch (233.7 mm) |
| Muzzle velocity | 2,065 feet per second (629 m/s)3 |
| Maximum range | 10,000 yards (9,100 m)4 |
The BL 9.2 inch guns Mk I - Mk VII were a family of early British heavy naval and coast defence guns in service from 1881 to the end of World War I. They were originally designed to use the old gunpowder propellants.
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History
Mk I and II
British 9.2 inch guns originated from a request by the Admiralty in 1879 for a gun comparable to Krupp's 24cm (9.45 inch) gun at the time. It was submitted to the Committee on Ordnance, which was considering the option of returning to breech-loading artillery after Britain's brief return to muzzle-loaders in the 1870s. A new breech-loading gun of 9.2 inches firing a 380-pound projectile was calculated to be suitable5. A total of 19 Mk I and Mk II guns of 26 calibres were made starting in 1881, but after lengthy delays and modifications proved unsatisfactory and none made it to sea.
Mk IIII - Mk VII
The 31.5 calibres versions, Mk III through to Mk VII became the first to be mounted on ships and deployed in general service.
Naval service
Guns equipped the following ships :
- Imperieuse class armoured cruisers launched in 1883 : Mk III
- Orlando class armoured cruisers launched 1886 : Mk V & VI
- Blake class protected cruisers launched 1889 : Mk VI
- Edgar class protected cruisers launched 1890 : Mk VI
- HMS Alexandra as re-gunned in 1891
- HMS Rupert as re-gunned in 1892
- M15 class monitors M19 - M28 launched 1915 : Mk VI guns from Edgar class cruisers.
Coast defence gun
Most Mk IV guns and some Mk VI guns were used in coast defences.
In the mid-late 1880s successful trials were carried out with RML 9-inch coast-defence guns firing at high angles in order to test the effectiveness of plunging fire on decks of ships. When surplus BL Mk IV and Mk VI guns became available in the 1890s they were likewise adapted to high-angle carriages, with their obsolete 3-motion breech mechanisms replaced by modern continuous-motion patterns to allow faster loading. Locations included Plymouth and Gibraltar6.
The elevation of up to 45° meant that the shell was at risk of slipping back after being rammed forward : only the copper driving band held the shell in place in a BL gun and they had not been designed to operate at such high angles. The solution adopted was to develop a special high-angle reduced-charge cartridge with a hollow up the centre, through which the gunner inserted a 1¼ inch diameter stick about 40 inches long made of beech wood, to prevent the projectile from slipping back before firing. A "light" 290 lb shell was used for high-angle firing, rather than the standard 380 lb shell.7.
World War I Railway gun
From 1915 onwards Elswick adapted a small number of Mk III, Mk IV and Mk VI guns, and mounted them on railway truck mountings for service on the Western Front in France and Belgium.8
Surviving examples
- 2 Mk IV guns at Fort Siloso, Sentosa Island, Singapore
- EOC Mk VII gun No. 7318 dated 1881, originally mounted at Signal Hill, Vaucluse at Royal Australian Artillery National Museum, North Head, Sydney, Australia
- A previously buried disappearing gun at Ben Buckler, Sydney, awaiting restoration
See also
Media related to BL 9.2 inch gun Mk I - VII at Wikimedia Commons- List of artillery by type#Naval artillery
Notes
- ^ a b c Text Book of Gunnery 1902, Table XII Page 336
- ^ Treatise on Ammunition 10th Edition 1915
- ^ 380 lb shell, with 164 lb brown prism powder or 53½ lb cordite propellant size 30. Text Book of Gunnery 1902. 175 lb brown powder is quoted for the Mk V gun in Text Book of Gunnery 1887.
- ^ 10,000 yards refers to naval mountings which had limited elevation : Text book of gunnery, 1902. Coast and rail mountings allowed greater elevation and hence range.
- ^ Hogg & Thurston 1972, page 164
- ^ Hogg & Thurston 1972, page 167
- ^ Treatise on Ammunition 10th Edition, published 1915. Pages 77, 142. High-angle cartridges were 44lb 12 oz or 16 lb 1 oz cordite MD, firing a 290-pound shell.
- ^ Hogg & Thurston 1972, page 168-170
References
- Text Book of Gunnery, 1887. LONDON : PRINTED FOR HIS MAJESTY'S STATIONERY OFFICE, BY HARRISON AND SONS, ST. MARTIN'S LANE
- Text Book of Gunnery, 1902. LONDON : PRINTED FOR HIS MAJESTY'S STATIONERY OFFICE, BY HARRISON AND SONS, ST. MARTIN'S LANE
- Hogg, I.V. and Thurston, L.F. (1972). British Artillery Weapons & Ammunition 1914-1918. Ian Allan, London. ISBN 7110 0381 5
- Tony DiGiulian, British 9.2"/31.5 (23.4 cm) Marks III to VII
External Links
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