Japan 大日本帝國海軍航空隊 Dai-Nippon Teikoku Kaigun Koukuu-tai Imperial Japanese Navy Air Service Aircraft Code Names & Designations 1912 - 1945

1912 - 1922: The Early Years

The first aircraft used by the Imperial Japanese Navy were imported from France and America in 1912. As the Imperial Japanese Army had already imported similar aircraft, the IJN used the same designations, which consisted of a Type designation based on the phonetic pronounciation of the first Japanese character of the manufacturer's name.

Example: Navy Type Ka Seaplane (Curtiss 1912 Seaplane).

In 1915 the Imperial Japanese Navy created a new designation system and existing aircraft were re-designated. From 1915 to 1922, the Imperial Japanese Navy used a series of consecutive katakana characters (I, Ro, Ha, Ni, Ho) (from the Iroha) along with the suffix "go" ("type") to designate aircraft. Modified aircraft added Ko, Otsu, Hei, Tei, Bo, Ki, Ko, Shin, Jin, Ki (from the 10 Stems of the Japanese zodiac) with "gata" or "kata" ("sub-type" or "model").

Example: I-go Otsu-gata Seaplane (Curtiss 1912 Seaplane).

Listing of early IJN aircraft.

1922 - 1931: The Interwar Years

In 1922, this system was replaced by a Type number based on the last two digits of the Japanese calendar year in which the aircraft was accepted for service, along with a description of the aircraft's role. Initially, the Taisho calendar year was used, then changing to the Showa year until Showa 3 (1928), at which point the National calendar year was used.

Example: Navy Type 10 Carrier Fighter.

Listing of interwar IJN aircraft.

1931 - 1945: The War Years

In 1931, Imperial Japanese Navy aircraft designations were expanded and revised further to include an experimental designation and a project designation, along with the official Type designation:

• Experimental designation: Starting in 1931, experimental aircraft were given a Shisaku Seizo (trial manufacture) designation, consisting of the Showa-era calendar year and Shi; for example, Experimental 10-Shi Carrier Attack Bomber (Showa 10, 1935). If the aircraft was accepted for service, it was given an offical designation (see below).
• Project Designation: Starting in the 1930s, aircraft were given a short title (Ki Go, symbols; and Ryaku Go, codes; or "project designation"); this was similar to the US Navy aircraft designation scheme, and consisted of four or five designators:
  1. Aircraft role
  2. Numerical sequence in role
  3. Manufacturer or designer
  4. Numerical modification of basic design
  5. If a particular aircraft was further modified to perform a different role than the original, a dash followed by a role suffix was added.
  Example: A6M2-N
  1. A = Carrier-borne fighter
  2. 6 = Sixth carrier fighter procured
  3. M = Mitsubishi
  4. 2 = Second variant of basic A6M design
  5. -N = Floatplane fighter modification of A6M design
• Official Designation: Aircraft which entered service were given an official designation (Seishiki Meisho, official or accepted designation). This consisted of a Type number made up of (usually) the last two digits of the Japanese calendar year in which the aircraft was accepted. Aircraft accepted after the Japanese year 2,599 (1939) were designated using only the last (single) digit of the year (i.e., Type 0 for 2,600 [1940], Type 1 for 2,601 [1941]). This type designation was then followed by a description of the plane's role. If several different aircraft with the same role were accepted in the same year, the Type number was suffixed with an additional number, depending on order of acceptance (i.e., Type 97-1 Fighter, Type 97-2 Fighter, etc.). If one of these aircraft was further modifed, it was given an additional model number (i.e., Type 97-2-2 Fighter). However, starting in 1942-43, this was replaced with a two-digit Model number; for example, the Type 0 Carrier Fighter Model 32 (three-two; third airframe change from original aircraft and second engine change from original aircraft). Additional minor modifications were signified with one of the following suffixes: Ko, Otsu, Hei, Tei, Bo, Ki, Ko, Shin, Jin, Ki (from the 10 Stems of the Japanese zodiac, or as a, b, c, d, e, f, etc. Examples include A6M3 Type 0 Carrier Fighter Model 32a and A6M5c Type 0 Carrier Fighter Model 52 Hei. This was again further modified in 1943, the Type number being dropped and only the popular name (see below) and Model number being used.
• Popular Name: Some aircraft were assigned popular names, which made it easier to refer to them in public without indicating their designation(s) (as this could give away how many and what type(s) of aircraft had been built; the popular name was never associated with any of the designations during the war; most factory workers, aircrew, etc., did not know the designations of their aircraft, other than perhaps the "Type" number). Names were chosen according to the following categories:
  • Special attack: Blossoms
  • Bombers: Mountains
  • Night fighters: Light
  • Fighters: Winds

Listing of World War II-era IJN aircraft, engine and other designations.

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