The B4Y entered service in 1936 with the proven Nakajima Hikari radial, providing a replacement for the troubled B3Y. Its 770-horsepower engine came from an established line of development informed by foreign experience. The biplane resembled the Swordfish and provided a usable torpedo and bombing platform for the war in China. B4Ys participated in the 1937 Panay incident and continued operating from carriers that could not handle their successors. Most were replaced in 1940.
Notable Point · 51:06-53:20
The B4Y is a pragmatic fallback for war and small carriers
The Hikari-powered B4Y replaces the troubled B3Y and remains usable from carriers that cannot operate its successors.