had many names, each depending on the period of its existence, and the circumstances at that time. Many of the names were

acronyms An acronym is a word or name formed from the initial components of a longer name or phrase. Acronyms are usually formed from the initial letters of words, as in ''NATO'' (''North Atlantic Treaty Organization''), but sometimes use syllables, as ...

that were derived from its military name or designation, which changed from time to time. The arsenal was sometimes known as "Kūgi-shō" (空技廠, a contraction of "Kōkū Gijutsu-shō" 航空技術廠).Francillon, p 446 The name Yokosuka prevailed however, even though it referred to the Arsenal's location at

Yokosuka is a city in Kanagawa Prefecture, Japan. , the city has a population of 409,478, and a population density of . The total area is . Yokosuka is the 11th most populous city in the Greater Tokyo Area, and the 12th in the Kantō region. The city ...

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 ...

.Mikesh, Robert and Shorzoe Abe. ''Japanese Aircraft 1910–1941''. London: Putnam, 1990.

History

The air arsenal's roots go back to 1869 when the

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 ...

(IJN) established a naval arsenal at Yokosuka, about 13 miles south of

Yokohama is the second-largest city in Japan by population and the most populous municipality of Japan. It is the capital city and the most populous city in Kanagawa Prefecture, with a 2020 population of 3.8 million. It lies on Tokyo Bay, south of To ...

Tokyo Bay is a bay located in the southern Kantō region of Japan, and spans the coasts of Tokyo, Kanagawa Prefecture, and Chiba Prefecture. Tokyo Bay is connected to the Pacific Ocean by the Uraga Channel. The Tokyo Bay region is both the most populous a ...

. The arsenal provided ship building, repair and replenishment to the Japanese Navy. It was also a storage depot where munitions and other assorted supplies were brought as they were purchased. When a number of foreign aircraft were purchased for evaluation, the Navy brought them to the arsenal for processing. The arsenal assembled the aircraft from their shipping boxes, and when assembled, they were flown by the pilots who had been sent abroad for flying lessons and evaluate the aircraft flown. Modifications to these aircraft were done as weaknesses were found, or when an improvement was incorporated. To facilitate this work, the IJN established the Aeroplane Factory, Ordnance Department at the arsenal's torpedo factory in May 1913. The next year, the first acronym was used was Yokosho, a contraction of . The arsenal was renamed in December 1919. The name was assigned by April, 1923, when the arsenal was moved to

Tsukiji Tsukiji (築地) is a district of Chūō, Tokyo, Japan. Literally meaning "reclaimed land", it lies near the Sumida River on land reclaimed from Tokyo Bay in the 18th century during the Edo period. The eponymous Tsukiji fish market opened in 193 ...

with several other Naval support units. The entire Tsukiji facility was destroyed in the

1923 Great Kantō earthquake The struck the Kantō Plain on the main Japanese island of Honshū at 11:58:44 JST (02:58:44 UTC) on Saturday, September 1, 1923. Varied accounts indicate the duration of the earthquake was between four and ten minutes. Extensive firestorms an ...

. Several names were used when the navy began establishment of the arsenal. Research was started again in 1924 when several aircraft were evaluated. Under the command of the newly formed Naval Air Headquarters, the was formed at Yokosuka on 1 April 1932. A large amount of draftsmen and Designers were transferred from the

Hiro Naval Arsenal The Hiro Naval Arsenal (''Hiro Kaigun Kōshō'' or ''Dai-Jūichi Kaigun Kōkū-shō'' (11th Naval Arsenal), often abbreviated as ''Hiroshō'') at Kure (呉), Hiroshima prefecture, was a production facility for seaplanes, flying boats, and aero engi ...

, ending aircraft production there.

The war years

During

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

, the arsenal was responsible for the design of several IJN aircraft, although the arsenal itself did not manufacture more than a few prototypes of the aircraft it designed. Its designs were mass-produced by companies such as

Aichi Kokuki was a Japanese aircraft manufacturer which produced several designs for the Imperial Japanese Navy. After the war, the company was reorganized as Aichi Machine Industry Co., Ltd (愛知機械工業) where they made small ''kei'' cars until 19 ...

, Watanabe Tekkōjo steel foundry, (renamed in 1943 to ), and the . Aircraft designed by the arsenal are usually designated by the manufacturer's letter "Y" for "Yokosuka". An example of the above is the Yokosuka D4Y1 which was mainly produced by Aichi. The D4Y1 and later models were also produced by the at Hiro.

Aircraft

;Torpedo bomber *

Yokosuka Twin-engined Seaplane is a city in Kanagawa Prefecture, Japan. , the city has a population of 409,478, and a population density of . The total area is . Yokosuka is the 11th most populous city in the Greater Tokyo Area, and the 12th in the Kantō region. The city ...

- 1916 biplane torpedo bomber; first Japanese twin-engine aircraft * B3Y - -1933 biplane torpedo bomber * B4Y - - 'Jean' 1936 biplane torpedo bomber ;Dive bomber * D2Y - prototype dive bomber, lost to the

Aichi D1A The Aichi D1A or Navy Type 94/96 Carrier Bomber ( Allied reporting name "Susie") was a Japanese carrier-based dive bomber of the 1930s. A single-engine, two-seat biplane based on the Heinkel He 50, the D1A was produced by Aichi for the Imperia ...

* D3Y - or - 1945 two-seat dive bomber/trainer based on the

Aichi D3A The Aichi D3A Type 99 Carrier Bomber ( Allied reporting name "Val") is a World War II carrier-borne dive bomber. It was the primary dive bomber of the Imperial Japanese Navy (IJN) and was involved in almost all IJN actions, including the at ...

* D4Y - - 'Judy' 1942 two-seat carrier-based dive bomber * D5Y - - Kamikaze version of the D3Y ;Reconnaissance aircraft *

Yokosuka Nakajima Tractor is a city in Kanagawa Prefecture, Japan. , the city has a population of 409,478, and a population density of . The total area is . Yokosuka is the 11th most populous city in the Greater Tokyo Area, and the 12th in the Kantō region. The city ...

- 1915 reconnaissance seaplane * Ho-go Otsu-gata Seaplane - 1916 reconnaissance seaplane * Ho-go Small Seaplane - 1917 reconnaissance seaplane *

Ro-go Ko-gata The Yokosuka Ro-go Ko-gata (YokoSho-shiki Ro-go Ko-gata) was a Japanese Surveillance aircraft, reconnaissance floatplane developed during the First World War by the Japanese Navy Arsenal at Yokosuka, and one of the first indigenous Japanese aircr ...

- 1918 reconnaissance floatplane * D4Y1-C - - 1942 ship-based reconnaissance version of D4Y, produced by Aichi * E1Y - - 1923 reconnaissance floatplane * Tatsu-go Reconnaissance Seaplane - 1925 reconnaissance seaplane prototype * 1-go Reconnaissance Seaplane - 1925 submarine-based reconnaissance seaplane * E5Y - - 1930 reconnaissance floatplane * E6Y - - 1933 submarine-based reconnaissance floatplane * E14Y - - 'Glen' 1941 submarine-based reconnaissance floatplane * R1Y - - prototype reconnaissance aircraft * R2Y - - 1945 prototype reconnaissance aircraft ;Flying boat * H5Y - - 'Cherry' 1939 maritime reconnaissance flying boat * H7Y - 'Tillie' 1939 prototype flying boat ;Trainer * I-go Ko-gata - 1920 seaplane trainer * K1Y - - 1925 biplane trainer * K2Y - - Japanese-built Avro 504 * K4Y - - 1933 floatplane trainer * K5Y - -'Willow' 1934 biplane trainer ;Transport * L3Y - - Yokosuka-built transport version of

Mitsubishi G3M The was a Japanese bomber and transport aircraft used by the Imperial Japanese Navy Air Service (IJNAS) during World War II. The Yokosuka L3Y (Allied reporting name "Tina"), was a transport variant of the aircraft manufactured by the Yokosu ...

;Special purpose * MXY1 - 1939 experimental parasol monoplane for aerodynamic research; built by Watanabe * MXY2 * MXY3 - experimental radio-controlled target glider (drone) * MXY4 - experimental radio-controlled target aircraft (drone) * MXY5 - transport glider * MXY6 - unpowered gliders for development of the

Kyushu J7W The Kyūshū J7W ''Shinden'' (震電, "Magnificent Lightning") was a World War II Japanese propeller-driven prototype fighter with wings at the rear of the fuselage, a nose-mounted canard, and pusher engine. Developed by the Imperial Ja ...

* MXY7 - - 'Baka' 1945 rocket-powered ''kamikaze'' attack aircraft * MXY8 - - training glider based on the Mitsubishi J8M; known as Ku-13 in IJA service * MXY9 - - motorjet powered version of MXY-8 (project only) * MXY10 - ground non-flying decoy of P1Y * MXY11 - ground non-flying decoy of

Mitsubishi G4M The Mitsubishi G4M was a twin-engine, land-based medium bomber formerly manufactured by the Mitsubishi Aircraft Company, a part of Mitsubishi Heavy Industries, and operated by the Imperial Japanese Navy from 1940 to 1945. Its official designati ...

;Bomber * P1Y - 'Frances' 1944 twin-engine bomber * - jet-powered version of the P1Y (project only)

References

Notes

Bibliography

*Francillon, R.J. ''Japanese Aircraft of the Pacific War'', Putnam, London, 1970, SBN 370 00033 1 *Mikesh, Robert and Shorzoe Abe. ''Japanese Aircraft 1910–1941''. London: Putnam, 1990. {{coord missing, Kanagawa Prefecture Yokosuka Imperial Japanese Navy Arsenals