BL 9.2 inch gun Mk III - VII

Infobox Weapon
name= Ordnance BL 9.2 inch gun Mk III - Mk VII


caption=
origin= United Kingdom
type= Naval gun
Coast defence gun
is_ranged=YES
is_bladed=
is_explosive=
is_artillery=YES
is_vehicle=
is_UK=YES
service=1881 - 1918
used_by=Royal Navy
wars=World War I
designer=
design_date=
manufacturer=
production_date=
number=
variants=Mk III, IV, V, VI, VII
weight=Mk III : 24 tons barrel & breech;
Mk V - VII : 22 tonsText Book of Gunnery 1902, Table XII Page 336]
length=
part_length=convert|290|in|mm|sigfig=4; (31.5 calibres)
width=
height=
crew=
cartridge= convert|380|lb|kg|sigfig=5
convert|290|lb|kg|sigfig=5 (High-angle guns) [Treatise on Ammunition 10th Edition 1915]
caliber=convert|9.2|in|mm|sing=on|sigfig=4
action=
rate=
velocity=convert|2065|ft/s|m/s|sigfig=3 [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.]
range=
max_range= convert|10000|yd|m
feed=
sights=
breech=
recoil=
carriage=
elevation=
traverse=The BL 9.2 inch guns Mk III - Mk VII were British 31.5-calibres naval and coast defence guns in service from 1881 to the end of World War I.

History

British 9.2 inch calibre guns originated from a request by the Admiralty for a gun comparable to Krupp's 24cm (9.45 inch) gun at the time, submitted to the Committee on Ordnance in 1879. A new gun of 9.2 inches firing a 380-pound projectile was calculated to be suitable [Hogg & Thurston 1972, page 164] . 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. Hence 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
*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 Gibraltar [Hogg & Thurston 1972, page 167] .

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. [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.] .

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. [Hogg & Thurston 1972, page 168-170]

ee also

*List of artillery#Naval guns

Notes

References

* [http://cgsc.cdmhost.com/u?/p4013coll11,230 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, [http://www.navweaps.com/Weapons/WNBR_92-31_mk3.htm British 9.2"/31.5 (23.4 cm) Marks III to VII]

External Links