Difference between revisions of "RML 10 inch 18 ton gun"

Latest revision as of 20:21, 2 July 2010

The RML 10 inch guns Mk I - Mk II were large rifled muzzle-loading guns designed for British battleships and monitors. They were also fitted to the Bouncer class flat-iron gunboats.^[4]

Design

The 10-inch gun was a standard "Woolwich" design (characterised by having a steel A tube with relatively few broad, rounded and shallow rifling grooves) developed in 1868, based on the successful Mk III 9-inch gun, itself based on the "Fraser" system. The Fraser system was an economy measure applied to the successful Armstrong design for heavy muzzle-loaders, which were expensive to produce. It retained the Armstrong steel barrel surrounded by wrought-iron coils under tension, but replaced the multiple thin wrought-iron coils shrunk around it by a single larger coil (10 inch Mark I) or 2 coils (Mark II); the trunnion ring was now welded to other coils; and it eliminated Armstrong's expensive forged breech-piece.^[5]

The gun was rifled with 7 grooves, increasing from 1 turn in 100 calibres to 1 in 40.^[2]

It was first used for the main armament on the central battery ironclad HMS Hercules, completed in late 1868.

A number of the Mk I guns on HMS Hercules and one of the two damaged guns in HMVS Cerberus suffered from cracked barrels. Presumably this is who only 18 Mk I guns were made. details

Ammunition

When the gun was first introduced in 1868, projectiles had several rows of projecting "studs" which engaged with the gun's rifling to impart spin. From the mid-late 1870s, spin was imparted by "gas checks" connected to the base of the projectile which engaged the rifling grooves, making studs unnecessary, and hence the shells were designated "studless".

The gun's primary projectile was "Palliser" shot or shell, an early armour-piercing projectile for attacking armoured warships. A large "battering charge" of 70 pounds "P" (pebble) or 60 pounds "R.L.G." (rifle large grain) gunpowder^[6] was used for the Palliser projectile to achieve maximum velocity and hence penetrating capability.

Common (i.e. ordinary explosive) shells and shrapnel shells were fired with the standard "full service charge" of 44 pounds "P" or 40 pounds R.L.G. gunpowder^[6], as for these velocity was not as important.

See also

• List of naval guns

Surviving examples

• 4 guns submerged near the remains of HMVS Cerberus in Half Moon Bay, Victoria, Australia (3 x Mk I & 1 x Mk II)
• Damaged Mk I gun No. 17 from HMVS Cerberus is on display at HMAS Cerberus, Victoria, Australia
• Mk II gun No. 67 at Southport Gates, Gibraltar
• A Mk II gun at Parsons Lodge Battery, Gibraltar
• Mk II No. 273 at Almeda Gardens, Gibraltar
• Mk II guns Several guns at Fort St Catherine, St George's Island, Bermuda (at least three are Mk II guns)
• A Mk II at the Citadel, Quebec City, Canada

One 10 inch Mk II Common Shell & one 10 inch Mk III Palliser Shot as part of the Victorian Navy display at the Geelong Maritime Museum, Australia. Details

Notes

References

• Treatise on the construction and manufacture of ordnance in the British service. War Office, UK, 1877
• Treatise on Ammunition. 2nd Edition 1877. War Office, UK.
• Manual for Victorian naval forces 1887. HMVS Cerberus website
• Treatise on Ammunition, 4th Edition 1887. War Office, UK.
• Sir Thomas Brassey, The British Navy, Volume II. London: Longmans, Green and Co. 1882

External links

• Diagram of gun on Casemate Traversing Platform, at Palmerston Forts Society website
• Diagram of gun on Dwarf "D" Pivot mounting, at Palmerston Forts Society website
• Diagram of gun on 7 foot Parapet "C" mounting, at Palmerston Forts Society website
• Diagram of gun on 7 foot Parapet "C" Long Range mounting, at Palmerston Forts Society website

1. ↑ Unit cost of £1005 10 shillings 2 pence is quoted in "The British Navy" Volume II, 1882, by Sir Thomas Brassey. Page 38
2. ↑ ^{2.0 2.1} Treatise on Construction of Service Ordnance 1877, page 292
3. ↑ 1,364 feet/second firing 400-pound projectile with "Battering charge" of 70 pound "P" (gunpowder). Treatise on Construction of Service Ordnance 1877, page 348. 1,028 feet/second firing 410-pound common shell with gas-check with 44 pounds "P" (gunpowder). Victorian Navy Handbook 1887, page 211.
4. ↑ Paloczi-Horvath, George (1996). From Monitor to Missile Boat Coast Defence Ships and Coastal Defence since 1860. Conway Maritime Press. p. 27. ISBN 0851776507. 
5. ↑ Treatise on Construction of Service Ordnance 1877, page 92-93
6. ↑ ^{6.0 6.1} Treatise on Ammunition 1877, page 220