The Yokosuka K4Y (or Navy Type 90 Seaplane Trainer) was a

Japanese Japanese may refer to: * Something from or related to Japan, an island country in East Asia * Japanese language, spoken mainly in Japan * Japanese people, the ethnic group that identifies with Japan through ancestry or culture ** Japanese diaspor ...

floatplane A floatplane is a type of seaplane with one or more slender floats mounted under the fuselage to provide buoyancy. By contrast, a flying boat uses its fuselage for buoyancy. Either type of seaplane may also have landing gear suitable for land, ...

trainer of the 1930s. A single engined two-seat

biplane A biplane is a fixed-wing aircraft with two main wings stacked one above the other. The first powered, controlled aeroplane to fly, the Wright Flyer, used a biplane wing arrangement, as did many aircraft in the early years of aviation. While ...

, 211 K4Ys were built between 1933 and 1940, serving as 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 ...

's basic floatplane trainer throughout the

Second World War 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 ...

Development and design

In 1930, the

Imperial Japanese Navy Air Service The was the Naval aviation, air arm of the Imperial Japanese Navy (IJN). The organization was responsible for the operation of naval aircraft and the conduct of aerial warfare in the Pacific War. The Japanese military acquired their first air ...

's basic seaplane trainer was the Yokosuka K1Y or Type 13 Seaplane Trainer, which had been in use from 1925, and it instructed the First Naval Air Technical Arsenal based 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 ...

to design a replacement. The design team, led by Jiro Saha and Tamefumi Suzuki designed a

single-bay A biplane is a fixed-wing aircraft with two main wings stacked one above the other. The first powered, controlled aeroplane to fly, the Wright Flyer, used a biplane wing arrangement, as did many aircraft in the early years of aviation. While a ...

with a welded steel-tube

fuselage The fuselage (; from the French ''fuselé'' "spindle-shaped") is an aircraft's main body section. It holds crew, passengers, or cargo. In single-engine aircraft, it will usually contain an engine as well, although in some amphibious aircraft t ...

and wooden wings, it being the first Japanese designed aircraft with such a fuselage. Yokosuka built two prototypes, powered by 90 hp (67 kW) Hatakaze four-cylinder air-cooled inline engines in 1930, flying in 1930, and after successful testing, a version powered by a 130 hp

Gasuden Jimpu The Gasuden Jimpu or Kamikaze (later produced by Hitachi) was a Japanese seven-cylinder air-cooled radial aircraft engine from the 1920s, 1930s and 1940s. It was the first aircraft engine produced by , often abbreviated to Gasuden, and the first ...

radial engine was ordered into production as the Navy Type 90 Seaplane trainer, with the short designation K4Y1.

Operational history

Production began at

Watanabe Watanabe ( and other variantsSee #Miscellaneous) is a Japanese surname derived from the noble and samurai Watanabe clan, a branch of the Minamoto clan, descending from the Emperor Saga (786-842), the 52nd Emperor of Japan, and refers to a loca ...

in May 1933, Watanabe building 156 by 1939, with production then transferring to Nippon Hikoki who built a further 53 in 1939–40. The K4Y1 started to replace the K1Y from 1933, remaining the Imperial Japanese Navy Air Service's principal basic seaplane trainer throughout the Pacific war. A few aircraft were released for civilian use.

Units using this aircraft

; *

Specifications (K4Y1 seaplane)

References

;Notes ;Bibliography * * {{Japanese Navy short aircraft designations World War II Japanese trainer aircraft K04Y, Yokosuka Floatplanes K4Y Biplanes Single-engined tractor aircraft