| BL 15-inch Mark I naval gun | |
| Origin: | United Kingdom |
| Is Ranged: | YES |
| Is Artillery: | YES |
| Is Uk: | YES |
| Service: | 1915–1959 |
| Used By: | United Kingdom |
| Design Date: | 1912 |
| Production Date: | 1912–1918 |
| Number: | 186 |
| Weight: | 100LT[1] |
| Length: | 650.4inches |
| Part Length: | 630inches L42 |
| Cartridge: | separate charges and shell |
| Cartridge Weight: | 1938lb |
| Caliber: | 15adj=onNaNadj=on |
| Rate: | 2 rounds per minute |
| Velocity: | 2450ft/s2640ft/s, with supercharge |
| Max Range: | 33550yd (Mk XVIIB or Mk XXII streamlined shell @ 30°)[2] HMS Vanguard – 37870yd @ 30°, with supercharges. |
| Recoil: | 46inches |
The BL 15-inch Mark I succeeded the BL 13.5-inch Mk V naval gun. It was the first British 15inches gun design and the most widely used and longest lasting of any British designs, and arguably the most successful heavy gun ever developed by the Royal Navy.[3] It was deployed on capital ships from 1915 until 1959 and was a key Royal Navy gun in both World Wars.
The BL 15-inch Mk I, designed by Vickers, Son, and Maxim in 1912, was an enlarged version of the successful BL 13.5-inch Mk V naval gun. It was specifically intended to arm the new
The barrel was 42 calibres long (i.e., length of bore was 15 in x 42 = 630 in) and was referred to as "15 inch/42". Overall length of gun: 650.4 inches, Weight of gun, excluding breech mechanism: 97 tons 3cwt. Weight of breech mechanism: 2 tons 17cwt. Rifling: polygroove, 76 grooves, uniform right-hand twist of one turn in 30 calibres. This wire-wound gun fired at a muzzle velocity of 2450ft/s (4 crh shell), 2,640 ft/s (6 crh shell) with supercharge. Weight of shell: 1,920 lbs (4 AP crh shell), 1,938 lbs (6 crh AP shell – 1937). Weight of charge: 428 lbs cordite, 490 lbs cordite for supercharge.[5] The firing life of a 15-inch gun was approximately 335 full charge firings using standard charges, after which it had to be re-lined.[6]
All shipboard mounts of the gun were in twin turrets. All mountings were designated Mk I, with an as-built maximum elevation of 20°, though some were subject to later modifications. HMS Hood, however, had its guns in a unique mounting, designated Mk II. Incorporating experience from the Battle of Jutland, the Mk II mounting had a maximum elevation of 30°, thus increasing the maximum range.[7] In the 1930s a modification of the Mk I mounting, designated the Mk I (N), was introduced for use in those capital ships that were completely reconstructed. The Mk I (N) mounting also increased the maximum elevation from 20° to 30°.[8] Maximum range in shipboard mountings was 33550yd (30° elevation). During World War II unreconstructed older battleships, with gun elevation limited to 20°, were supplied with supercharges to increase their maximum range to 29930yd at 2638ft/s using the Mk XVIIB or Mk XXII projectile, while HMS Vanguard could theoretically range to 37870yd while using supercharges at a gun elevation of 30°. Coastal artillery mountings with higher elevations could reach 44150yd. The Mk I mounting had a revolving weight of 750 tons (1915) and 785 tons (1935). The Mk I (N) had a revolving weight of 815 tons; the Mk I (N) RP12 mounts of HMS Vanguard had a revolving weight of 855 tons. The Mk II mounts of HMS Hood had a revolving weight of 860 tons.[9]
The BL 15-inch Mark I gun proved its effectiveness at the Battle of Jutland in 1916, scoring hits out to 19500yd, a record for naval gunnery at that time.[10]
In World War II the gun was responsible for the longest range shell-hit ever scored by one battleship on another in combat. At the Battle of Calabria on 9 July 1940, gained a hit on the Italian battleship with her first salvo at 26400yd.[11] In the Attack on Mers-el-Kébir, when the French fleet was largely neutralised following the fall of France to the Germans, the BL 15-inch Mark I gun (arming, and HMS) was responsible for the destruction by a magazine explosion of the old battleship, and the disabling and beaching (deliberate running aground in shallow water) of the old battleship and the new battleship . Dunkerques main 225mm armour belt was twice penetrated by 15-inch shells, which destroyed its fighting and steaming abilities.[12]
These guns were used on several classes of battleships from 1914 until, the last battleship to be built for the Royal Navy, completed in 1946.
Warships armed with the BL 15-inch Mark I gun:
186 guns were manufactured between 1912 and 1918.[14] They were removed from ships, refurbished, and rotated back into other ships over their lifetime.
Two guns, one formerly from (left gun) and the other originally mounted in, but later moved to (right gun), are mounted outside the Imperial War Museum in London.