100-ton gun facts for kids
Quick facts for kids Armstrong 100-ton gun |
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"Rockbuster" at Napier of Magdala Battery, Gibraltar
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| Type | Naval gun Coast defence gun |
| Place of origin | United Kingdom |
| Service history | |
| In service | 1877-1906 |
| Production history | |
| Designer | Elswick Ordnance Company |
| Unit cost | £16,000 (£176,000 today) |
| No. built | 15 |
| Specifications | |
| Mass | 103 tons |
| Barrel length | bore: 362.9 inches (9.22 m) (20.5 calibres) |
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| Shell | HE, AP, Shrapnel, 2,000 pounds (910 kg) |
| Calibre | 450-millimetre (17.72 in) |
| Recoil | 1.75 m |
| Elevation | 10° 30' |
| Traverse | 150° |
| Muzzle velocity | 1,548 feet per second (472 m/s) |
| Maximum firing range | 6,600 yards (6,000 m) |
The 100-ton gun (also known as the Armstrong 100-ton gun) was a 17.72 inches (450 mm) rifled muzzle-loading (RML) gun made by Elswick Ordnance Company, the armaments division of the British manufacturing company Armstrong Whitworth, owned by William Armstrong. The 15 guns Armstrong made were used to arm two Italian battleships and, to counter these, British fortifications at Malta and Gibraltar.
Origins
Around 1870 the largest gun made by UK firms was the 320 mm RML (rifled, muzzle-loading) gun, with a mass of 38 long tons (38.6 t), firing an 818-pound (371 kg) projectile capable of piercing 16.3 inches (410 mm) of mild steel at 2,000 yards (1,800 m). This weapon was adequate for the needs of the time, but the progress of gun technology was very rapid. French industries soon made a 420 mm, 76 tonne gun. This led the Royal Navy to ask for an 80 long ton (81 t) gun.
Armstrong, the main British artillery producer, began a project for creation of an even larger weapon, an 18 in (460 mm) gun, also called the '100 ton'. Armstrong offered it to the Royal Navy, which rejected the gun, deeming it too heavy and costly.
Description
These new artillery pieces were enormous weapons for their time. Their weight was comparable to that of the much later Iowa-class 406mm/50cal guns, even though their barrels were quite short. They were muzzle-loading guns, with a rifled tube and rigid mount. Each gun required a crew of 35 men, including 18 men to handle the ammunition.
The gun was 9.953 m long. The barrel's maximum outer diameter was 1.996 m, which reduced to 735 mm at the muzzle. The construction method of an inner steel tube surrounded by multiple wrought iron coils, was very complex, with several structures containing one another. The internal barrel was 30 feet 3 inches (9.22 m) long, or 20.5 calibers. The weight of the gun was 103,888 kg, or about 100 tons.
Firing was mechanical or electrical, with an optical system for aiming.
The gun crews could fire a projectile once every six minutes. Muzzle velocity was 472 m/s and maximum elevation was 10° 30'. At maximum charge (204 kg?) and maximum elevation, a projectile could achieve a range of only 5,990 meters, but at that distance the projectile could still pierce 394 mm of steel (it is not clear if it was mild or hardened).
The weight of the mount was: 20,680 kg (mobile mounts with 18 wheels), 24,118 kg (platform) and 2,032 kg (base). The platform was sloped at 4 degrees to slow the recoil. On the platform mount, hydraulic systems powered chains that traversed the guns through an arc of 150 degrees; another hydraulic system provided elevation.
Ammunition
This was a second-generation RML gun, equipped with polygroove rifling and firing only studless ammunition with automatic gas-checks for rotation.
Projectiles were of three types, all weighing 2,000 pounds (910 kg) and having a diameter of 17.7 inches (450) mm:
- Armour-piercing (AP) Palliser, 44 inches (1.12 m) long, steel forward section, capable of piercing 21 inches of steel at 2,000 yd (530 mm at 1,800 m). with a 32-pound (14.5 kg) explosive internal charge.
- High explosive (HE) Common, 48+1⁄2 inches (1.23 m) long, with thinner walls and a 78-pound (35 kg) HE charge.
- Shrapnel shell: 45 inches (1.1 m) long, with a charge of only 5 pounds (2.3 kg) HE, but also 920 bullets of 4 ounces (110 g) each.
Firing charges were polygonal in shape, with 399 x 368 mm maximum width and length. They were made of 1 cwt (51 kg) 'Large Black Prism' propellant, and four or five were needed for every shell fired at maximum power. The recoil was 1.75 m as two hydraulic pistons in the rear part of platform absorbed the remaining energy.
Service
Sale to Italy
After the reunification of Italy, the Regia Marina began an innovative program to field the best and most powerful battleships of the time, the first being the Duilio-class, armed with 380 mm guns. They were already very powerful, but in February 1874 when the UK started to build HMS Inflexible, armed with 406 mm guns, Italian admirals called for even more powerful guns, to hold the lead in battleship design.
On 21 July 1874, Armstrong signed a contract with Italy to deliver eight of its 100-ton guns, enough to arm Duilio and her sister-ship Dandolo. During firing trials on 5 March 1880, one of Duilio's guns cracked while firing at the maximum charge. At the suggestion of the British Army, it was officially established that the maximum practical charge was 204 kg and not 255.
The two surviving guns
The guns at Napier of Magdala Battery and at Fort Rinella are still intact and one can visit them. The guns were too costly to demolish and were left as junk, but both were later restored to display condition. Fort Rinella is under the guardianship of Fondazzjoni Wirt Artna - the Malta Heritage Trust. The pink paint on the Fort Rinella gun was added only recently; originally they were not painted at all.
Gallery
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17.72 inch projectile
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Twin turret, Duilio
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RML 17.72 inch, Gibraltar
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RML 17.72 inch, Gibraltar
