In 1932, the Imperial Japanese Navy had a requirement, 7-
Shi, for a new
torpedo bomber to replace the
Mitsubishi B2M. The air arsenal at Yokosuka prepared its own design to meet this requirement, competing against designs by
Mitsubishi and
Nakajima. The resulting aircraft was a three-seat single-engine
biplane, with a fuselage of steel tube construction and two-bay wooden wings that could
fold rearwards for storage aboard
aircraft carriers. It was powered by a single
Hiro Type 91 W engine rated at . 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, 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,
Watanabe and the
Hiro Naval Arsenal, 129 being produced by the time that production finished in 1936. ==Operational history==