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Imperial Japanese Navy The Imperial Japanese Navy (IJN; Kyūjitai: Shinjitai: ' 'Navy of the Greater Japanese Empire', or ''Nippon Kaigun'', 'Japanese Navy') was the navy of the Empire of Japan from 1868 to 1945, when it was dissolved following Japan's surrender ...

submarines in commission during the 1920s. They were Japan's first true seagoing submarines and the earliest Japanese submarines classified as "second-class" or "medium" submarines.

Design and description

The Type F submarines were designed by the Italian firm

Fiat-Laurenti Fiat Chrysler Automobiles N.V. (FCA) was an Italian-American multinational corporation primarily known as a manufacturer of automobiles, commercial vehicles, auto parts and production systems. The Italian holding company Exor was the largest ...

and built under license by Kawasaki at

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Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

.Gray, p. 247. The Type F submarines were the Imperial Japanese Navy′s first true seagoing submarines, and when the Japanese adopted a three-tiered classification system of its submarines as first-class ('' I''), second-class or medium ('' Ro''), and third-class ('' Ha'') on 1 November 1924,Gray, p. 245. the Type F submarines were the earliest to receive the second-class classification, as reflected in their low numbers in the ''Ro'' series, and in fact they were the earliest Japanese submarine classified as anything higher than third-class. As built, Type F submarines had no deck gun, but soon after they were completed each of them had a /40 gun installed on her deck. The Type F submarines had non-cylindrical hulls intended to provide extra internal space, but the Japanese considered the hulls weak despite the provision of additional

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s during construction to reinforce them. Because of their disappointing performance, they did not serve as the basis for any later Japanese submarine classes.

Class variants

The ''Type F'' submarines were divided into two subclasses: * *

''Type F1 (Ro-1-class)''

The F1 subclass was ordered under the 1915–1916 naval program. Two were constructed between 1917 and 1920:

''Type F2 (Ro-3-class)''

The F2 subclass (''Ro-3''-class) was ordered in 1918. It was an improved version of the F1 subclass with a modified

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. The

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diesel engine The diesel engine, named after Rudolf Diesel, is an internal combustion engine in which ignition of the fuel is caused by the elevated temperature of the air in the cylinder due to mechanical compression; thus, the diesel engine is a so-call ...

s were unreliable and the F2 subclass′s top surface speed of was well below the intended . Additional F2 subclass units planned under the 1919 construction program were cancelled and replaced by the new ''Kaichū''-type and Type L submarines. Three submarines of the F2 subclass were constructed between 1919 and 1922:

Characteristics

Sources

References

Bibliography

* Gray, Randal, ed., ''Conway′s All the World′s Fighting Ships 1906–1921'', Annapolis, Maryland: Naval Institute Press, 1985, . {{DEFAULTSORT:F0 type submarines F type submarine Submarines of the Imperial Japanese Navy