The Nakajima B5N was the standard carrier torpedo bomber of the Imperial Japanese Navy (IJN) for much of World War II. Its full designation was "Type 97 Carrier Attack Bomber" (九七式艦上攻撃機) and its Allied reporting name was Kate.
Despite being obsolete by 1941 (having lack of armor, self-sealing fuel tanks and being slow), the B5N operated throughout the whole war, due to the delayed development of its successor, the B6N.
There were two variants. The B5N1 first saw combat in the Sino-Japanese War where it revealed several weaknesses. An effort to solve them included fitting the more powerful Sakae Model 11 engine (this was the same engine which powered the A6M Zero). This improved version was designated the B5N2 and primarily saw service with the Imperial Japanese Navy, achieving success in the early part of World War II by sinking several battleships and aircraft carriers.
