130mm L/55 Type 32 naval gun
| 130 mm L/55 Type 32 naval gun | |
|---|---|
| File:130mm L55 Menghe.png Diagram of the Type 32 gun in the "G-type" mount. | |
| Type | Naval and coastal gun |
| Place of origin | Greater Menghean Empire |
| Service history | |
| In service | 1932—1945 |
| Used by | Greater Menghean Empire |
| Wars | Pan-Septentrion War |
| Production history | |
| Designed | 1930—1932 |
| Produced | 1932—1945 |
| Specifications | |
| Weight | 6210 kg (gun only) |
| Barrel length | 7.15 meters (bore) |
| Caliber | 130mm |
| Breech | sliding block |
| Recoil | 52 cm |
| Elevation | varies with mount |
| Traverse | varies with mount |
| Rate of fire | 5-13 shots/min (depending on mounting) |
| Muzzle velocity | 840-890 m/s (depending on model and ammunition) |
| Maximum firing range | 25,710 km at 50 degrees |
The 130mm L/55 Type 32 naval gun (Menghean: 130밀리 55구경장 32식 해군 대포, il-san-ryong milli o-o gugyŏngjang sam-i-sik haegun daepo) was a 130mm (5.1 inch) naval gun used by the armed forces of the Greater Menghean Empire throughout the Pan-Septentrion War. It was the main gun armament of all destroyer classes introduced after 1932, and it served as a secondary weapon on some mid-war cruisers, battleships, and aircraft carriers. While originally designed as an anti-surface weapon, the 130mm L/55 Type 32 was later adapted for dual-purpose use. Its mountings ranged from open, manually-cranked single mounts to twin mounts with powered elevation and traverse.
Background
Beginning in the mid-1920s, the Menghean Navy had started looking into potential successors to the 100mm gun used on the Jindo-class destroyers, which was hampered by poor range and a low explosive filling. An interim solution, planned for the Daejŏng-class destroyers, was to use the 125mm L/50 Type 10 gun carried by existing Menghean light cruisers, but this weapon was of 1910 vintage and the Navy wanted a more advanced replacement in the same size category.
As part of the 1930 revision to the 1923 Nine-Power Naval Treaty, signatory countries, including Menghe, were forbidden from commissioning any destroyer with a main gun greater than 130 millimeters in caliber. Faced with this restriction, as well as a cap in overall destroyer tonnage, the Imperial Menghean Navy commissioned an immediate design study to gain the maximum possible performance out of a treaty-compliant destroyer weapon.
While prior Menghean-designed naval guns had used calibers in multiples of 25 centimeters, the new weapon was built at 130 millimeters to match the treaty limit. It also had a long 55-caliber barrel to ensure maximum propellant burn. Trials of prototype guns were conducted in 1931 and 1932, and the weapon was rushed into service on an accelerated schedule, as its development was the main bottleneck in completing the Daejŏng-class destroyers; the first four ships of the class were commissioned without their main batteries installed. Full-scale production began in 1932, and would continue until 1945.
Description
Designed to make the most of the treaty limitations, the Type 32 naval gun was among the best destroyer weapons of the war in terms of its anti-surface performance. Its long barrel and modern propellant gave it very good range, and its 35-kilogram SAP shell was the heaviest destroyer projectile of the war, narrowly surpassing the 130mm ammunition used by the Federation of Socialist Republics. Menghean engineers had consulted extensively with their Ostlandian counterparts in designing the armor-piercing shell, resulting in a streamlined projectile with excellent ballistics and very good anti-armor performance. The shell could reportedly penetrate 75 millimeters of horizontal armor at ranges of up to 9,000 meters, allowing destroyers armed with the Type 32 to engage most contemporary cruisers at long range.
This high performance, of course, came with its own tradeoffs. The long, well-reinforced barrel was heavy and unwieldy, and produced powerful recoil when firing, necessitating a strong mount and adequate reinforcement of the ship's deck. Early guns were also hand-cranked, which for such an unwieldy weapon meant slow traverse and elevation rates. The long recoil stroke and relatively low trunnion meant that the manual mounts could only elevate to 30 degrees, though even at this elevation their range was respectable by the standards of the time.
The breech used a sliding block configuration, with the breechblock sliding to the left during the reloading process. On twin mounts, the right-hand gun was mirrored, with the breechblock sliding to the right. Rate of fire under optimal conditions - i.e., with a fresh crew operating a stable open mount at near-horizontal elevation - was about 10 rounds per minute, but it could degrade rapidly under adverse conditions with manual loading. In light of this, enclosed mounts used a semi-automatic loading process, in which shells were manually placed behind the breech and automatically rammed in.
In the anti-aircraft role
Originally, the Type 32 was designed as a dedicated anti-surface gun, a decision which was not unusual in the early 1930s. Two years after its introduction, however, the Navy conducted tests with a Type 32 gun in a one-off single-gun AA mount, believing that its high muzzle velocity and good ballistic properties would make it an excellent anti-aircraft weapon.
The prototype AA mount performed well on initial trials, exhibiting a high ceiling and good dispersion, and it was chosen for destroyer-mounted dual-purpose guns and cruiser- and battleship-mounted secondaries in the late 1930s. Actual service, however, quickly turned up faults with the gun: its heavy single-piece ammunition led to rapid fatigue among turret crews, especially at high elevations, such that the sustained rate of fire often fell to four rounds per minute or less. Ultimately, the Navy favored the 100mm L/40 Type 27 in the anti-aircraft role, as it compensated for poor accuracy with a high volume of fire.
Mounts
- G-type
- The first type of mounting used with the 130mm L/55, this was a simple pedestal mount with hand-cranked controls for elevation and traverse. Maximum elevation was limited to 30 degrees, and maximum depression was -7 degrees. It was mainly used in coastal artillery mounts, and sometimes on auxiliary ships.
- N-type
- The N-type was a modification of the G-type, with the main difference being the addition of a distinctive squared-off gun shield with a slightly sloping roof and a face 15 millimeters thick. It also had a built-in analog display system connected to the ship's fire-control apparatus, though the guns were cranked manually to match displayed settings. Elevation and depression were identical to the G-type. This model was used on the Daejŏng-class destroyers and Paengsŏng-class destroyer leaders and was refitted to the Gijang-class cruisers.
- D-type
- Experimental anti-aircraft mount used in Navy trials. Single barrel, manual elevation and traverse, no gun shield.
- R-type
- Twin mount used on destroyers of the Sŏnsan, Imsil, and Samrangjin classes. It had powered traverse and elevation controls, and an elevation range of -5 to +45 degrees. It also had fully enclosed sides and a full floor, making it more crew-friendly, though the rear was open and could be covered with a canvas sheet. While theoretically a dual-purpose mount, its modest traverse speed and low maximum elevation hampered its usefulness in the anti-aircraft role, and it was succeeded by better mounts on later destroyers.
- M-type
- Twin mount used on the Chŏnjin-class battleships and some mid-war cruisers. It was fully enclosed, with a higher traverse and elevation rate than the R-type destroyer turret, making it the most effective anti-aircraft mount for the Type 32 gun. Ammunition was supplied through an automatic hoist in a protected barbette under the gun, and maximum elevation was 85 degrees. The M1 type mount was used on battleships, and the M2 type mount was used on cruisers; they differed mainly in the presence of thicker armor and a more powerful traverse motor on the M1.
- B-type
- Dedicated anti-aircraft mount in a roughly cylindrical shielded housing. Originally designed for aircraft carriers, it was mainly used on coastal AA mounts. Unlike other dual-purpose mounts for the 130mm L/55 Type 32, the guns were mounted closer together and were not individually sleeved.
- S-type
- The second-generation dual-purpose destroyer mount, the S-type turret had a maximum elevation of 80 degrees and a much better traverse and elevation rate than the R-type turret before it. It was also fully enclosed, though its face, walls, and roof were only 10mm thick. It incorporated a partially automated loading system attached to an unarmored barbette under the turret; the S2 variant, introduced in 1939, corrected reliability problems in earlier models.