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BL 13.5-inch Mk I – IV naval gun

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Adapted from the English Wikipedia article BL 13.5-inch Mk I – IV naval gun, available under CC BY-SA 4.0Updated 29 November 20258 sources
BL 13.5 inch naval gun Mk I–IV
Company typeNaval artillery
IndustryOrdnance manufacturing
FoundedEarly 1880s
Headquarters
United Kingdom
ProductsLarge-calibre breechloading naval guns
OwnerWoolwich Arsenal

The BL 13.5 inch naval gun Mk I—often referred to as the 67-ton gun—represented Britain's inaugural effective large-calibre breechloading naval artillery piece. Its initial design phase took place in the early 1880s, with deployment commencing towards the decade's end. The variants Mk I through Mk IV[note 1] all shared a length of 30 calibres and exhibited comparable design and operational characteristics.

Royal Navy service

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Conceived to rival the large-calibre artillery mounted on the French Amiral Baudin-class battleships, the development and production of this gun proceeded at a slower pace than originally anticipated.[1] The initial vessels outfitted with the 13.5-inch weaponry were four battleships from the Admiral-class battleship class: Anson, Camperdown, Howe, and Rodney. These ships were laid down between 1882 and 1883 and entered service in 1888–89.[2] Both Howe and Rodney shared similar dimensions with their predecessor, Collingwood, which had been designed around 12-inch, 45-ton guns. However, the heavier mass of the 13.5-inch guns—including their mountings and ammunition—resulted in an increase in draught from approximately 26 feet 4+1⁄2 inches (8.039 m) to 27 feet 10 inches (8.48 m), as well as a displacement augmentation of about 800 long tons (810 t).[3] The later-built Anson and Camperdown featured enlarged dimensions to accommodate these weapons. Each of these four battleships installed their pair of 13.5-inch guns within twin barbettes positioned along the centreline at both extremities of the superstructure.

Following these classes, the same calibre guns were installed on the subsequent Trafalgar class class vessels laid down in 1886 and on the later Royal Sovereign-class battleship class battleships initiated in 1889.

Coast defence role

One Mk III gun was installed as a disappearing gun specifically for coastal protection at Penlee Battery, Plymouth.

Service in Italy

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These guns were also exported to Italy, equipping the Re Umberto-class ironclad class, including the Re Umberto, Sicilia, and Sardegna. These vessels were laid down in 1884 and entered service between 1893 and 1895.

Manufacturing details

The gun's construction comprised the following components:[4]

  • Tube A,
  • Breech-piece,
  • Hoop B,
  • Tube B,
  • Hoops 1-C and 2-C,
  • Tube C,
  • Hoops 1-D and 2-D,
  • Jacket.

The assembly process was as follows:[4]

  1. The breech-piece, along with hoop B and tube B, was shrunk onto tube A, which extended to the muzzle.
  2. Hoop 1-C was shrunk over the breech-piece; these two parts were longitudinally connected at the breech end by a screwed steel bush designed to accommodate the breech screw.
  3. Tube C and hoop 2-C were then shrunk over hoop B and tube B.
  4. Hoop 1-D was shrunk around hoop 1-C and part of tube C, secured at the breech with a screwed steel ring.
  5. Hoop 2-D was shrunk over tube C just ahead of hoop 1-D.
  6. The jacket was shrunk around hoop 1-D at the breech end.
  7. Thrust collars formed externally on hoop 1-D were used to attach the gun to its mounting, as the gun lacked trunnions.

The bore length measured 405 inches (10.3 m) (equivalent to 30 calibres), with rifling extending 333.4 inches (8.47 m). The rifling featured an increasing twist system containing 54 grooves; it began with a twist rate of 1 turn in 120 at the breech, gradually increasing to 1 turn in 30 at a distance of 166.7 inches (4.23 m) from the muzzle, after which it maintained a consistent twist of 1 in 30.[4] The chamber measured 66.5 inches (1.69 m) in length and had a volume of 17,100 cubic inches (0.280 m3).[5] The breech mechanism was a hydraulically operated interrupted-screw breech-block, which fully detached from the gun during loading due to the absence of a carrier.[5]

These guns were designed and produced by Woolwich Arsenal.[3] Production faced considerable setbacks during the 1880s, causing significant delays in completing the first four battleships outfitted with this artillery. The primary issue originated from "the faulty principle of placing liners in the bores which cracked during proof testing, necessitating extensive repairs before rendering the guns serviceable."[1]

Operating characteristics

The gun launched a projectile weighing 1,250-pound (570 kg) propelled by 630 pounds (290 kg) of brown powder (SBC). This combination produced a muzzle velocity of 2,016 feet per second (614 m/s), enabling the shell to penetrate 28.2 inches (720 mm) of wrought iron armor at a distance of 1,000 yards (0.91 km).[4][5] With the advent of smokeless powder, the charge was updated to 187 pounds (85 kg) of cordite-44, which increased the muzzle velocity of the 1,250 lb shell to 2,099 feet per second (640 m/s).[5] The projectiles typically featured a calibre radius head (crh) of two.[5]

For the Admiral and Trafalgar classes, the gun's maximum elevation was limited to 13 degrees. In contrast, the Royal Sovereign class and Hood allowed a slightly greater elevation of 13.5 degrees. At this higher elevation, the maximum range reached 11,950 yards (10.93 km) when using brown powder and extended to 12,620 yards (11.54 km) with cordite propellant.[5]

The shells were equipped with copper driving bands designed to engage the rifling grooves inside the barrel. After approximately 100 to 110 full-charge firings with brown powder, rifling near the breech would experience wear, necessitating an increase in driving band width. To address this, ships carried "augmenting strips"—long copper strips hammered into the recessed cannelure ring that held the driving band on the projectile. Once gun wear exceeded what augmenting strips could compensate for, barrels were returned to the manufacturer for relining.[6] Reduced charges lessened barrel wear.[6]

Under optimal conditions, a twin 13.5-inch gun mounting aboard Anson was capable of firing two rounds "within a couple of minutes or even less".[7]

See also

Weapons of comparable role, performance and era

Notes

  1. ↑ Mk I = Mark 1, Mk II = Mark 2, Mk III = Mark 3, Mk IV = Mark 4. Britain used Roman numerals to denote marks (models) of ordnance until after World War II. Hence this article covers the first four models of British 13.5 inch guns

References

  1. ↑ 1.0 1.1 Parkes, British Battleships, p319.
  2. ↑ Parkes, British Battleships, p317.
  3. ↑ 3.0 3.1 Parkes, British Battleships, p318.
  4. ↑ 4.0 4.1 4.2 4.3 'Garbett, Naval Gunnery, p120
  5. ↑ 5.0 5.1 5.2 5.3 5.4 5.5 British Naval Guns 1880-1945, No 2, by NJM Campbell, in Warship Volume V p96.
  6. ↑ 6.0 6.1 'Garbett, Naval Gunnery, p124
  7. ↑ 'Garbett, Naval Gunnery, p123

Bibliography

  • Text Book of Gunnery Archived 12 July 2012 at archive.today, 1902. London: Printed for His Majesty's Stationery Office by Harrison and Sons, St. Martin's Lane
  • Naval Gunnery, Captain H Garbett RN, George Bell & Sons, 1897.
  • British Battleships, Oscar Parkes, originally published by Seeley Service & Co in 1957; United States Naval Institute Press edition, 1990. ISBN 1-55750-075-4

External links

Wikimedia Commons has media related to BL 13.5 inch naval gun Mk I - IV.

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