The Yokosuka B3Y Navy Type 92 Carrier Attack Aircraft was a disappointing level bomber that was produced to replace the Mitsubishi B2M Type 89 Carrier Attack Aircraft
The B3Y was designed by a team led by Tamefumi Suzuki. His task was to produce an aircraft as reliable as the Mitsubishi B1M Type 13 (the Type 13 dated to 1924, the Type 89 to 1929). In early documents the aircraft was even referred to as the Type 13 Carrier Attack Aircraft Modified.
The B3Y had a welded steel tube structure for the fuselage and a wooden structure for the wings, both fabric covered. The twin-bay wings could be foled backwards for storage. It had three open cockpits, for the pilot, bombardier/ navigator and radio operator/ gunner. The pilot was under the front of the wing, the bombardier just below the trailing edge and the gunner at the rear.
The B3Y performed poorly in its flight tests. The new engine was unreliable, the aircraft was unstable and the controls poor. However the rival Mitsubishi and Aichi designs were even worse, and so a modified version of the Yokosuka design was accepted for production in August 1933, as the Navy Type 92 Carrier Attack Aircraft B3Y1.
The aircraft was powered by a Hiro Type 91 twelve-cylinder W water-cooled engine, based on an imported French Lorraine engine. The prototype used a 500hp engine, production aircraft a 600hp version. Both versions were unreliable.
The B3Y could carry a single 1,763lb torpedo or a torpedo-shaped auxiliary fuel tank, or a range of bombs from a single 1,102lb bomb to six 66lb bombs. It has a fixed forward firing machine gun and a flexibly mounted rear firing machine gun.
Production of the B3Y was split between Aichi, Watanabe and the Hiro Arsenal. The prototype was built at Kusho (the current name for the Yokosuka arsenal). A total of 128 production aircraft were built - 75 at Aichi in 1933, 23 at Watanabe in 1933-36 and 30 at the Hiro Arsenal.
The B3Y was a disappointment in service, and suffered severe criticism with the Naval Air Service. It did see combat in the Second Sino-Japanese War, where it proved to be a good accurate level bomber, capable of being used against small targets. Unfortunately its poor reliability and serviceability reduced the number of aircraft available at any one time.
In some units it was replaced by the elderly Mitsubishi B1M Type 13 Carrier Attack Bomber, because the older aircraft was more reliable. In other units they were replaced by the Aichi D1A1 Navy Type 94 Carrier Bomber, Aichi D1A2 Navy Type 96 Carrier Attack Bomber and the Yokosuka B4Y Type 96 Carrier Attack Aircraft 'Jean' (also known as the Kusho B4Y, after the official name of the Yokosuka arsenal at the time).
Engine: Hiro Type 91 twelve-cylinder W water-cooled engine
Crew: 3 (pilot, bombardier/ navigator, radio operator/ gunner
Span: 44ft 3.75in
Length: 31ft 2in
Height: 12 2.75in with tail down
Empty weight: 4,078lb
Loaded weight: 7,054lb
Max speed: 136mph
Endurance: 4hr 30mins
Armament: One fixed forward firing 7.7mm machine gun, one flexibly mounted dorsal machine gun
Bomb load: One 1,763lb torpedo, one 1,102lb bomb, two 551lb bombs or ix 66lb bombs