The Kugisho B3Y, or Navy Type 92 Carrier Attack Bomber, also popularly titled Yokosuka B3Y, was a Japanese

carrier-based Carrier-based aircraft, sometimes known as carrier-capable aircraft or carrier-borne aircraft, are naval aircraft designed for operations from aircraft carriers. They must be able to launch in a short distance and be sturdy enough to withstand ...

torpedo bomber A torpedo bomber is a military aircraft designed primarily to attack ships with aerial torpedoes. Torpedo bombers came into existence just before the First World War almost as soon as aircraft were built that were capable of carrying the weight ...

of the 1930s. It was designed by the Naval Air Technical Arsenal at Yokosuka, and while unimpressive during testing, it was ordered into service by 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 ...

and used until replaced by more capable aircraft.

Development and design

In 1932, the Imperial Japanese Navy had a requirement, 7-''Shi'', for a new

torpedo A modern torpedo is an underwater ranged weapon launched above or below the water surface, self-propelled towards a target, and with an explosive warhead designed to detonate either on contact with or in proximity to the target. Historically, su ...

bomber A bomber is a military combat aircraft designed to attack ground and naval targets by dropping air-to-ground weaponry (such as bombs), launching aerial torpedo, torpedoes, or deploying air-launched cruise missiles. The first use of bombs dropped ...

to replace the

Mitsubishi B2M The Mitsubishi B2M was a Japanese carrier-based torpedo bomber of the 1920s and 1930s. It was built by Mitsubishi to a design by Blackburn Aircraft of Britain and was operated by the Imperial Japanese Navy. Design and development In 1927, the ...

. The air arsenal at Yokosuka prepared its own design to meet this requirement, competing against designs by

Mitsubishi The is a group of autonomous Japanese multinational companies in a variety of industries. Founded by Yatarō Iwasaki in 1870, the Mitsubishi Group historically descended from the Mitsubishi zaibatsu, a unified company which existed from 1870 ...

and Nakajima. The resulting aircraft was a three-seat single-engine

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 ...

, with a fuselage of steel tube construction and two-bay wooden wings that could fold rearwards for storage aboard

aircraft carrier An aircraft carrier is a warship that serves as a seagoing airbase, equipped with a full-length flight deck and facilities for carrying, arming, deploying, and recovering aircraft. Typically, it is the capital ship of a fleet, as it allows a ...

s. It was powered by a single

Hiro Type 91 The Hiro Type 91, (full designation Hiro Type 91 520 hp water-cooled W-12), was a 12-cylinder, water-cooled, W engine developed for aircraft use by the Imperial Japanese Navy in the mid-1930s. Power was in the 450 kW (600 hp) ran ...

W engine A W engine is a type of piston engine where three or four cylinder banks use the same crankshaft, resembling the letter W when viewed from the front. W engines with three banks of cylinders are also called "broad arrow" engines, due to their shap ...

rated at 450 kW (600 hp). Testing proved that the aircraft had poor stability and control, and that the engine was unreliable. The competing Mitsubishi and Nakajima aircraft were even less successful however, and after modifications made by Tokuichiro Gomei of

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 ...

, the aircraft was accepted by the Navy in August 1933 as the Kugisho Navy Type 92 Carrier Attack Bomber, with a short designation of B3Y1, with production by

Aichi is a prefecture of Japan located in the Chūbu region of Honshū. Aichi Prefecture has a population of 7,552,873 () and a geographic area of with a population density of . Aichi Prefecture borders Mie Prefecture to the west, Gifu Prefectu ...

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 locat ...

and 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 ...

, 129 being produced by the time that production finished in 1936.

Operational history

The B3Y1 continued to be prone to engine problems, which frequently caused the type to be grounded. It served operationally in the early part of the

Second Sino-Japanese War The Second Sino-Japanese War (1937–1945) or War of Resistance (Chinese term) was a military conflict that was primarily waged between the Republic of China and the Empire of Japan. The war made up the Chinese theater of the wider Pacific Th ...

, gaining a good reputation for accurate level bombing against small targets. The Yokosuka B3Y was gradually phased out of operational service, being replaced by Aichi's D1A

dive bomber A dive bomber is a bomber aircraft that dives directly at its targets in order to provide greater accuracy for the bomb it drops. Diving towards the target simplifies the bomb's trajectory and allows the pilot to keep visual contact througho ...

and Yokosuka's B4Y torpedo bomber.

Operators

; *

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 ...

Specifications (B3Y1)

References

External links