Japanese 53 cm torpedo

Numerous 53 cm (21-inch, 533 mm) torpedoes have been used by the Imperial Japanese Navy and its successor, the Japan Maritime Self-Defense Force, since their first development just before the First World War.

Torpedoes of 21-inch caliber are the primary size category used worldwide. In Japan, they are used by surface ships and submarines, and comprise the predominant majority of submarine torpedoes; historically, aircraft and midget submarines used smaller 45 cm torpedoes, and surface ships additionally used 61 cm torpedoes. Japan also employs 32 cm torpedoes which conform to the NATO 12.75-inch (323.8 mm) standard; these are dedicated ASW weapons, often delivered via aircraft.

Prior to 6 October 1917, imperial measurements were used. After this date, metric units were used. As such, the 21-inch torpedoes were designated as 53 cm torpedoes. Japanese torpedoes have usually conformed to the 45 cm (17.7-inch or 18-inch), the 53 cm (21-inch), and the 61 cm (24-inch) calibers.

The Japanese type designation scheme has mostly used three different approaches. Units designed prior to the end of the Second World War were designated by either the regnal era year or the imperial year. In 1873, the Gregorian calendar was introduced in Japan; during the latter half of the 20th century, Japan increasingly switched to using this system, and as such, more recent torpedoes have type designations denoting Gregorian years. As an example of all three systems, a torpedo designed or accepted for service in 1980 could potentially be called either a Type 55 (Showa Era year 55), a Type 40 (Imperial Year 2640), or a Type 80 (Gregorian year 1980).

During the Second World War, Japanese torpedoes were superb. Rigorous live-fire testing in real-world conditions resulted in highly reliable designs. The Japanese were more willing to conduct dangerous experiments, an attitude that was also reflected in their highly realistic fleet exercises. Japan also possessed the fastest torpedoes in the world, having persevered in their pursuit of using pure oxygen as the oxidizer instead of air, whereas other navies abandoned the idea.

After the Second World War, Japan imported American torpedoes. These included the Mark 14, Mark 23, Mark 32, Mark 34, Mark 37, Mark 44, and Mark 46. This page presently only lists torpedoes which were indigenously produced in Japan.

After a brief period of postwar stagnation in the field, the Japanese experienced a revival of torpedo development. During the 1970s, indigenous designs became globally competitive.

Type 43 21-inch
Upscaled version of the Type 43 18-inch. The Type 43 was based upon plans supplied by Whitehead (Whitehead Mark 5). Generally similar to the Type 38 No.2B and the Type 42, utilizing four-cylinder radial engines. The Type 43 was the only foreign torpedo design adopted for use with 21-inch torpedo tubes during the first half of the 20th century. Designed 1909, in service 1910. Used on surface ships.

Specifications:


 * Entered service: 1910
 * Propulsion: Dry heater
 * Weight: 1187 kg
 * Length: 6.39 m
 * Explosive charge: 130 kg Shimose
 * Range and speed: 8000 m at 27 kn

Type 44 21-inch
Based upon plans supplied by Whitehead (Whitehead Mark 5) and the Type 43. Designed 1910, in service 1911. Used on surface ships and submarines. This torpedo was the first type deployed on Japanese submarines, initially the F, L, and Kaichu types. The Type 44 torpedo series existed in both 18-inch and 21-inch calibers, each having a No.1 and a No.2 variant developed. The Type 44 was the first Japanese design to fully transition to steam for its wet heater cycle.

Specifications:

Type 44 No.1 21-inch
 * Entered service: 1911
 * Propulsion: Wet heater
 * Weight: 1325 kg
 * Length: 6.70 m
 * Explosive charge: 110 kg Shimose
 * Range and speed: 7000 m at 36 kn, 10000 m at 27 kn

Type 44 No.2 21-inch
 * Entered service: 1911
 * Propulsion: Wet heater
 * Weight: 1293 kg
 * Length: 6.70 m
 * Explosive charge: 110 kg Shimose
 * Range and speed: 7000 m at 36 kn, 10000 m at 27 kn

Type 6
The first type classified using metric measurements. Also referred to as the 6th Year Type in literature, referring to Taisho Era year 6 (1917). Design work commenced in 1914 and was completed in 1917; in service 1918. Used on surface ships and submarines. In the aftermath of the Russo-Japanese War, Japan pursued a tentative Eight-Eight Program, which stipulated the necessity for eight modern battleships of at least 20 thousand tons displacement and eight modern battlecruisers of at least 18 thousand tons displacement. These ships would be armed with new, increasingly powerful armaments, including torpedoes of 21-inch caliber, as opposed to the 18-inch standard common during the war. The torpedoes designed for this program were the Type 6, soon to be followed by the 61cm (24-inch) Type 8. Alongside the new design, the decision was made to switch to metric units for all present and future torpedo programs. In 1922, the Washington Naval Treaty was signed, and the large new torpedoes were reassigned to new designs of cruisers and destroyers. In this way, the 53cm torpedo caliber became increasingly significant.

Specifications:


 * Entered service: 1918
 * Propulsion: Wet heater
 * Weight: 1432 kg
 * Length: 6.84 m
 * Explosive charge: 203 kg Shimose
 * Range and speed: 7650 m at 36 kn, 10000 m at 32 kn, 15000 m at 26 kn

Type 89
Designed 1929, in service 1931. Used on submarines. The Type 89 replaced the Type 6 in the Junsen and Kaidai class submarines after its adoption, and remained in service until being retired in 1942. Common during the Second World War as an older and less expensive alternative to the Type 95, especially during the first half of the war. For this torpedo, the type designation refers to Imperial Year 2589. The type designation 89 was reused in 1989, referring to the Gregorian year.

Specifications:

Type 89 Early
 * Entered service: 1931
 * Propulsion: Wet heater (kerosene-air)
 * Weight: 1625 kg
 * Length: 7.15 m
 * Explosive charge: 295 kg Type 91
 * Range and speed: 5500 m at 45 kn, 6200 m at 43 kn, 11000 m at 36 kn

Type 89 Late
 * Entered service: 1939
 * Propulsion: Wet heater (kerosene-air)
 * Weight: 1668 kg
 * Length: 7.16 m
 * Explosive charge: 300 kg Type 97
 * Range and speed: 5500 m at 45 kn, 6000 m at 43 kn, 10000 m at 35 kn

Type 92
Design work commenced 1921, completed 1925. Mod 1 was ready for production in 1934. Electric propulsion (lead-acid batteries). Deemed unnecessary at the time due to peacetime considerations, and consequently not put into series production. Re-engineered in 1942 using elements of the German G7e design after ten samples of the G7e were delivered to Japan that year. This resulted in the Mod 2, and production was started that year to supplement the high demand for the Type 95. The Type 92 was cheaper to produce than the Type 95. The Mod 2 was also used to investigate the possibility of an acoustic homing system, the first of its kind in Japan. Used on submarines.

Specifications:


 * Entered service: 1934 (Mod 1), 1942 (Mod 2)
 * Propulsion: Battery (lead-acid)
 * Weight: 1720 kg
 * Length: 7.15 m
 * Explosive charge: 330 kg Type 97
 * Range and speed: 7000 m at 28-30 kn

Type 94 Mod 1
Designed 1934. Two variants existed, a Type 94 Mod 1 and a Type 94 Mod 2. The Type 94 Mod 1 was the 53cm variant. Heavy kerosene-oxygen torpedo for aircraft use; not commonly deployed, it could be delivered by flying boats like the H6K. Used on aircraft.

Specifications:


 * Entered service: 1934
 * Weight: 1517 kg
 * Length: 6.70 m
 * Explosive charge: 393 kg Type 97
 * Range and speed: 4500 m at 45 kn
 * Max airdrop speed: 145 kn

Type 95 Mod 1


Designed 1935, in service 1938. Smaller version of the Type 93 ("Long Lance") kerosene-oxygen torpedo. The two variants of the Type 95, especially the pre-war Mod 1, were ubiquitous as submarine armament during the Second World War. Used on submarines.

Specifications:


 * Entered service: 1938
 * Propulsion: Wet heater (kerosene-oxygen)
 * Weight: 1665 kg
 * Length: 7.15 m
 * Explosive charge: 405 kg Type 97
 * Range and speed: 9000 m at 49-51 kn, 12000 m at 45-47 kn

Type 96
Designed 1941, in service 1942. The Type 96 designation is ostensibly to fill a sequential designation gap, and not denoting the year of adoption. Redesigned version of the Type 95 Mod 1 torpedo, using 36% oxygen instead of pure oxygen, to reduce starting problems. Used on submarines.

Specifications:


 * Entered service: 1942
 * Propulsion: Wet heater (kerosene-air, oxygen-enriched)
 * Weight: 1730 kg
 * Length: 7.15 m
 * Explosive charge: 550 kg Type 97
 * Range and speed: 4500 m at 48-50 kn

Type 95 Mod 2
Designed 1943, in service 1944. Used on submarines. Redesigned and improved version of the Type 95 Mod 1 torpedo that traded some of its range for a much heavier explosive payload. The nose cone of the torpedo had a more pointed design, influenced by the design of the Italian W 270/533.4 x 7.2 Veloce torpedo, samples of which were delivered to Japan during the Second World War. This nose cone design would be reused for several other torpedoes as well.

Specifications:


 * Entered service: 1944
 * Propulsion: Wet heater (kerosene-oxygen)
 * Weight: 1730 kg
 * Length: 7.15 m
 * Explosive charge: 550 kg Type 97
 * Range and speed: 5500 m at 49-51 kn, 7500 m at 45-47 kn

Type 54
Main article: Type 54 torpedo (ja)

Designed 1953, in service 1954 (Mod 1). Development program completed 1966 (Mod 3). The first indigenous postwar design. During the initial development phase, the torpedo was referred to as an Acoustic Target in official documents, due to secrecy and the sensitive political situation at the time. The physical construction of the torpedo was influenced by the German G7es "Zaunkonig", and the seeker head design was influenced by the American Mark 32. Propulsion was electric (lead-acid battery). The original variant was the Type 54 Mod 1, a straight-running torpedo for use by torpedo boats. This was unsuccessful due to reliability problems, including a propensity of the torpedo to sink immediately after launch. The Type 54 Mod 2 remedied these problems and added an acoustic homing system, the first of its kind in Japan. Type 54 Mod 2 was only capable of seeking targets in the horizontal plane, useful for targeting vessels on the surface. The Type 54 Mod 3 added three-dimensional acoustic homing, allowing the torpedo to be used for ASW. Used on surface vessels such as the Ayanami, Akizuki and Kitakami class destroyers, and submarines, such as the first postwar indigenously-designed submarine Oyashio.

Specifications:


 * Entered service: 1954 (Mod 1), 1955 (Mod 2), 1966 (Mod 3)
 * Propulsion: Battery (lead-acid)
 * Weight: 1600 kg
 * Length: 7.60 m
 * Explosive charge: 100 kg TNT
 * Range and speed: 6000 m at 24 kn
 * Maximum depth: Unknown, over 200 m

Type 55
In service circa 1960s-1970s. American Mark 37 torpedo manufactured in Japan, also designated as the Mark 37-0-N (Mark 37 Mod 0, the version without wire guidance). Other variants of the Mark 37 were imported, not manufactured domestically, and remained in service until 1987. The Type 55 designation is ostensibly to fill a sequential designation gap, and not denoting the year of adoption. Contemporary to this torpedo program, the Oshio was originally designed with two HU-201 shortened stern torpedo tubes dedicated for use of Mark 37-variant torpedoes; however, this design feature was deemed of limited effectiveness and never used.

During the Yomaru No.10 Incident (ja) in 1974, Mitsubishi Heavy Industries successfully implemented a rush modification of the Type 55 to give it an optional straight-run capability, overriding the doppler sonar of the seeker head.

Type 72
Main article: Type 72 torpedo (ja)

Designed 1966, in service 1972. Straight-running torpedo. Initially projected to use ethanol as fuel and nitric acid as the oxidizer; the final version used high-test peroxide (hydrogen peroxide) as the oxidizer. The exhaust consisted of water vapor and carbon dioxide, which eliminated the formation of a surface wake trail. Used on submarines such as the Uzushio class and Type 11 torpedo boats (ja). Following the adoption of the Harpoon missile in the 1980s, the non-homing Type 72 was deemed obsolescent. The torpedoes were withdrawn from service in 1994 and eventually scrapped.

Specifications:


 * Entered service: 1972
 * Propulsion: Bipropellant H2O2-Ethanol
 * Weight: Unknown
 * Length: 6.25 m
 * Explosive charge: 300 kg TNT
 * Range and speed: 10000 m at 65 kn, 20000 m at 45 kn
 * Maximum depth: Shallow setting (surface runner)

Type 80
Main article: Type 80 torpedo (ja)

Development began in 1965, and concluded in 1975. Unit trials began the same year. Accepted for service in 1980. Re-engineered variant of the American Mark 37 torpedo, with superior performance. The diameter of the torpedo body is the same as the American Mark 37, at 483mm; likewise, the torpedo is wire-guided, with active and passive acoustic homing capabilities. The torpedo possesses pattern-running capabilities for autonomous target search. Some of the unit specifics remain classified; remains in active service as of 2024. Used on submarines.

Specifications:


 * Entered service: 1980
 * Propulsion: Battery (silver oxide)
 * Weight: Unknown, above 700kg
 * Length: 5.00 m
 * Explosive charge: 150 kg HBX-3
 * Range and speed: 14630 m at 34 kn, 33000 m at 22 kn
 * Maximum depth: Unknown, over 300 m

Type 89
Main article: Type 89 torpedo (ja)

Development work began in 1970 and was completed in 1984. Adopted for service in 1989. Uses Otto Fuel II in its propulsion system. In 1993, an improved Type 89B variant was adopted. Wire-guided with active and passive acoustic homing, and a maximum depth of 900m for its Type 89B variant. The Type 89 features similar performance to the American Mark 48 torpedo. Some of the unit specifics remain classified. Used on submarines.

Specifications:


 * Entered service: 1989
 * Propulsion: Monopropellant Otto Fuel II
 * Weight: 1760 kg
 * Length: 6.25 m
 * Explosive charge: 267 kg High Explosive
 * Range and speed: 39000 m at 55 kn, 50000 m at 40 kn
 * Maximum depth: 500-640 m Type 89, 900 m Type 89B

Type 18
Development began in 2012, adopted for service in 2018. First production deliveries were made in 2022; incremental development continued between 2018 and 2022. Successor to the Type 89, using Otto Fuel II propellant like its predecessor. Wire-guided with passive and active acoustic homing; stated capabilities include advanced target and decoy recognition, as well as increased stealth. Specifications remain classified. Used on submarines.