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IMPERIAL JAPANESE NAVY (JAPAN)

SUBMARINES

"A-Hyoteki" and "Ko-Hyoteki" midget submarines (1934)

HA3 1939

Names

"A-Hyoteki":

第1号艦 <1-go>

第2号艦 <2-go>

"Ko-Hyoteki":

 波1 - 52 <HA1 - 52>

54 - 61 <HA54 - 61>

Builders

Mitsubishi, Yokohama: 1-go

Kure K K: 2-go, HA1, 2

Ourazaki, Kure: HA3 - 52, 54 - 61

Commissioned

1934: 1-go, 2-go

1936: HA1, 2

1938 - 1942: HA3 - 52, 54 - 61

Losses

4 boats (7/12/1941), 3 boats (30/5/1942), 4 boats (31/5/1942), HA8, HA22, HA38 and 5 other boats (1942), 3 boats (1942 - 1943)

Transfers

none

Discarding all survived: surrendered 8/1945 and BU

 

Displacement standard, t

 

Displacement normal, t

 / 45.3

Length, m

23.9

Breadth, m

1.85

Draught, m

1.85

No of shafts

1

Machinery

1 electric motor

Power, h. p.

600

Max speed, kts

19 - 24

Fuel, t

none

Endurance, nm(kts) 80(6) / 80(6)
Armament

2 - 450 TT (bow, 2)

Complement

2

Diving depth operational, m

 

Ship project history: Works on midget submarines have begun in Japan in 1933. According to Naval Staff plans midget submarines were supposed to use for attack of enemy bases and anchorages. To a site of operation they should be carried by specialised carrier submarines. In the conditions of the strict privacy two experimental midgets were built in 1934. For concealment of true assignment of boats they were officially classified as "target submarines" (A-Hyoteki). On results of trials in the project necessary improvements were brought, then serial building of midget submarines under designation Ko-Hyoteki has been developed. As carriers seaplane carriers Chiyoda and Chitose and Hei-Gata (C) type submarines were arranged.

At designing the basic thrust became on achievement of a high submerged speed. For this purpose submarines received powerful (for so small ship) electric motor, and hull have given streamlined spindle-shaped form. This combination has ensured to first Ko-Hyoteki submarines 23kts submerged speed (subsequent boats because of the brought modificatons reached 18-19kts). Two 450mm TTs placed in a bow one over another were basic weapon. First two submarine had no CT.

Modernizations: None.

Naval service: Unfortunately, the information about fates of Japanese midget submarines had scrappy and frequently inconsistent character. It is known, that during an attack to Pearl Harbor 7/12/1941 5 midgets of A type were lost. 3 more boats of this type were lost 30/5/1942 in Diego Suarez area and 4 in Sydney harbour 31/5/1942. During battles at Solomons in 1942 8 midgets of A type were lost (including ĶA8, 22 and 38). 3 more A type boats were lost off Aleutian in 1942-1943.

A type

© Ivan Gogin, 2008-14