BL 13.5-inch Mk I – IV naval gun facts for kids
Quick facts for kids Ordnance BL 13.5 inch gun Mk I - IV |
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The forward 13.5-inch (343-mm) gun turret of the battleship HMS Hood
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| Type | Naval gun |
| Place of origin | United Kingdom |
| Service history | |
| Used by | United Kingdom Kingdom of Italy |
| Production history | |
| Designer | Woolwich |
| Designed | 1880 |
| Variants | Mk I, II, III, IV |
| Specifications | |
| Mass | 67-69 tons barrel & breech |
| Barrel length | 405 inches (10.29 m) bore (30 calibres) |
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| Shell | 1,250 pounds (570 kg) |
| Calibre | 13.5-inch (342.9 mm) |
| Muzzle velocity | 2,016 feet per second (614 m/s) |
| Effective firing range | 12,000 yards (11,000 m) |
The BL 13.5 inch naval gun Mk I was a huge and powerful weapon. It was Britain's first really successful large naval gun. This type of gun was designed in the early 1880s. It started being used on warships in the late 1880s. There were several versions, called Mk I to Mk IV. They were all similar in size and how well they worked. These guns were sometimes called the "67-ton gun" because of their massive weight.
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Battleship Power
These powerful guns were made to compete with the large guns on new French battleships. It took a long time to develop and build them. The first ships to get the 13.5-inch gun were four battleships from the Admiral-class battleship class. These were Anson, Camperdown, Howe, and Rodney.
These ships were started between 1882 and 1883. They were finished around 1888 and 1889. The Howe and Rodney were originally planned for smaller guns. But the new 13.5-inch guns were much heavier. This extra weight made the ships sit lower in the water. It also made the ships weigh about 800 tons more.
The Anson and Camperdown were built a bit later. They were made larger to handle the heavy guns better. All four of these battleships carried their 13.5-inch guns in pairs. These guns were placed in special armored towers called barbettes. These towers were located at the front and back of the ship.
Later, these guns also went on the Trafalgar class class battleships. These ships were started in 1886. They also armed the Royal Sovereign-class battleship class. These powerful ships began construction in 1889.
Protecting the Coast
One special Mk III gun was used to defend the coast. It was placed at Penlee Battery in Plymouth. This gun was a "disappearing gun." This meant it could pop up to fire and then hide away. This made it harder for enemies to hit.
Italian Warships
Some of these big guns were also sold to Italy. They were used to arm the Re Umberto-class ironclad class battleships. These ships included Re Umberto, Sicilia, and Sardegna.
These Italian ships were started in 1884. They were finally ready for service in 1893 and 1895.
How the Gun Was Made
The 13.5-inch gun was built from several strong metal parts. These parts were carefully fitted together. The main parts included:
- A central tube
- A breech-piece (the back part where the shell goes)
- Several strong metal hoops and tubes
- A jacket (an outer layer)
The gun was put together by shrinking metal parts over each other. This made the gun very strong. For example, the breech-piece and some hoops were shrunk over the main tube. Other hoops and tubes were then shrunk over those layers. This layered design made the gun very tough.
The gun did not have trunnions. These are pins that usually hold a gun in its mounting. Instead, special collars on the gun helped secure it. These collars connected the gun to its mounting.
The inside of the gun's barrel was about 405 inches long. This is about 30 times its diameter. The inside of the barrel had special grooves called rifling. These grooves made the shell spin as it left the gun. This spinning made the shell fly straight and accurately. The rifling started with a gentle twist. It then became a tighter twist closer to the muzzle.
The gun had a special breech-block. This was a heavy metal plug that sealed the back of the gun. It was operated by hydraulics, which use liquid pressure. This made it easier to open and close. The breech-block had to be completely removed for loading.
These guns were designed and built by the Royal Arsenal in Woolwich. There were big delays in making the guns in the 1880s. This held up the completion of the first battleships. The problem was that inner linings in the gun barrels kept cracking. It took a long time to fix these issues.
How the Gun Worked
The 13.5-inch gun fired a very heavy shell. Each shell weighed about 1,250 pounds. It used a special type of gunpowder called brown powder. About 630 pounds of this powder was used for each shot. This powder pushed the shell out of the gun at a speed of about 2,016 feet per second. This was fast enough to punch through thick iron armor.
Later, a new type of gunpowder called smokeless propellant was used. This was a type of Cordite. With this new powder, the shell could fly even faster. It reached speeds of about 2,099 feet per second.
On the Admiral and Trafalgar class ships, the guns could be aimed up to 13 degrees high. On the Royal Sovereign class and HMS Hood, they could aim slightly higher, up to 13.5 degrees. When aimed at 13.5 degrees, the gun could shoot a shell almost 12,000 yards. That's about 6.8 miles!
The shells had a copper band around them. This band helped the shell grip the rifling inside the barrel. After about 100 to 110 shots, the rifling near the back of the gun would start to wear out. When this happened, the copper bands on the shells had to be made wider. This was done by adding "augmenting strips" of copper. If the gun became too worn, it had to be sent back to the factory to be repaired.
These guns could fire quite quickly for their size. On the Anson, two 13.5-inch guns could fire a shot in about two minutes or even less.
See also
- List of naval guns
Similar Weapons
- 340mm/28 Modèle 1881 gun - A French gun that was similar in its role and power.
Images for kids
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Barbette mounting on Re Umberto
