18-inch/48-caliber Mark 1 gun
| 18"/48 caliber Mark 1 gun | |
|---|---|
| Type | Naval gun |
| Place of origin | United States |
| Service history | |
| Used by | US |
| Production history | |
| Designed | 1920 |
| Produced | Never finished in this configuration |
| Specifications | |
| Mass | 177.8 long tons (180.7 t) |
| Length | 864 in (21,946 mm) |
| Shell | 2,900 lb (1,315 kg) |
| Caliber | 18 in (457 mm) |
| Muzzle velocity | 2,700 ft/s (823 m/s) |
| 16"/56 caliber Mark 4 gun | |
|---|---|
| Type | Naval gun |
| Place of origin | United States |
| Service history | |
| Used by | US |
| Production history | |
| Produced | 1927 |
| Specifications | |
| Mass | 185.2 long tons (188.2 t) |
| Length | 915 in (23,241 mm) |
| Shell | 2,100 lb (953 kg) |
| Caliber | 18 in (457 mm) |
| Muzzle velocity | 3,000 ft/s (914 m/s) |
| Effective firing range | 49,383 yd (45,156 m) at 40° with 2,100 lb AP shell |
| 18"/47 caliber Mark A gun | |
|---|---|
| Type | Naval gun |
| Place of origin | United States |
| Service history | |
| Used by | US |
| Production history | |
| Produced | 1942 |
| Specifications | |
| Mass | 177.0 long tons (179.8 t) |
| Length | 846 in (21,488 mm) |
| Shell | 3,850 lb (1,746 kg) |
| Caliber | 18 in (457 mm) |
| Muzzle velocity | 2,400 ft/s (732 m/s) |
| Effective firing range | 43,453 yd (39,733 m) at 40° with 3,850 lb AP shell |
The 18"/48 caliber Mark 1 – United States Naval Gun was the initial name and design for large caliber naval gun in the early 1920s. After the Washington Naval Treaty prohibited the development of guns larger than 16 in (406 mm), the gun was relined and finished as a high velocity 16"/56 Mark 4 gun. After the start of World War II, the gun was again relined to 18" and tested with a new Super Heavy Shell.
Description
After World War I, the erstwhile allies were poised to start a massive and costly naval arms race, with Great Britain, United States, and Japan creating plans for large fleets of new battleships and battlecruisers. The 18"/48 cal Mark 1, designed in 1920, was the result of the resulting progression to larger and more heavily armed capital ships. It was designed to fire a 2,900 lb (1,315 kg) AP shell at a muzzle velocity of 2,700 ft/s (823 m/s). The gun prototype was halfway completed when the Washington Naval Treaty of 1922 prohibited the development of guns larger than 16-inches. Consequently, the prototype was converted to a long barrel 16-inch gun and thus never fired in its original design configuration.
Despite the treaty, battleship studies conducted in 1927-1928 had considered this gun, but was rejected due to excessive weight, very short liner life, poor deck penetrating capability. The gun's size and weight meant that fewer 18-inch guns could be carried than 16-inch gun on a ship of a given size, while the large size and weight of the shells also reduced rate of fire.
16"/56 caliber Mark 4
The 18"/48 cal Mark 1 was finished with an extra thick 16-inch liner, and the resulting weapon became the 16"/56 cal Mark 4. The gun was first tested at the Dahlgren proving grounds in 1927, with tests continuing into the 1930s. It fired a 2,100 lb (953 kg) AP shell at 3,000 lb (1,361 kg) muzzle velocity, with a range of 49,383 yd (45,156 m) at 40° elevation. The high muzzle velocity of the prototype resulted in very short liner life of only 45 rounds, with a predicted liner life of 125 full charge rounds for the service weapon.
18"/47 caliber Mark A
In 1938, with Japan's refusal to sign the Second London Naval Treaty and worsening situation in Europe and Asia, battleship studies once again considered 18-inch caliber main guns. During the early design stages of a 45,000-ton "slow" battleship alternative to the "fast" battleship design that would eventually result in the Iowa-class, the 18"/48 cal gun option was considered in several proposals. The 16"/56 cal Mark 4 had its threaded tip cut off and was then relined to 18-inches; this weapon was then designated as the 18"/47 cal Mark A and was used to test a 3,850 lb (1,746 kg) "Super Heavy" AP shell, which the gun fired at 2,400 ft/s (732 m/s). Ultimately, it was decided that a 16"/50 cal gun offered the best combination of performance and weight, and the new 16"/50 caliber Mark 7 gun was used by both the Iowa class battleship and the Montana class battleship design.
Construction
The built-up gun is constructed of liner, A tube, jacket, nine hoops, six locking rings, a separate yoke ring and screw box liner. The breech mechanism was a down-swinging Welin block with vertical lever operating gear. Chromium plating of the bore was considered in the 1940s but never carried out.
See also
- List of naval guns
- List of World War II artillery
- 40 cm/45 Type 94 naval gun
- List of the largest cannon by caliber
References
- Sumrall, Robert F. (1988). Iowa Class Battleships. Annapolis, Maryland: Naval Institute Press. ISBN 0-87021-298-2.
- Garzke, William H.; Dulin, Robert O. Jr. (1995). Battleships: United States Battleships 1935–1992 (Rev. and updated ed.). Annapolis: Naval Institute Press. ISBN 978-0-87021-099-0. OCLC 29387525.
- Friedman, Norman (1986). U.S. Battleships: An Illustrated Design History. Annapolis: Naval Institute Press. ISBN 0-87021-715-1. OCLC 12214729.
External links
