Nakajima B5N
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The Nakajima B5N (Japanese: 中島 B5N, Allied reporting name: Kate) was the Imperial Japanese Navy's standard torpedo bomber for the first years of World War II. Although, like its Allied counterparts the TBD Devastator and Fairey Swordfish, the type was obsolescent by 1939, B5Ns were flown nearly throughout the whole war. Although primarily used as a carrier-based aircraft, it was also used as a land-based bomber on occasions.
The B5N was designed by a team led by Katsuji Nakamura in response to a 1935 specification by the Navy for a torpedo bomber to replace the Yokosuka B4Y. Internally designated Type K by Nakajima, it successfully competed with the Mitsubishi B5M for a production contract. The first prototype flew in January 1937 and was ordered into production soon afterwards with the full designation Type 97 Carrier Attack Bomber.
It would not be long until the B5N would see combat, first in the Sino-Japanese War, where combat experience revealed several weaknesses in the original B5N1 production model. These were mainly concerned with the lack of protection that the design offered its crew and fuel tanks. Keen to maintain the high performance of the type, the Navy was reluctant to add weight in the form of armour, and instead looked to obtaining a faster version of the aircraft in the hopes of out-running enemy fighters. The B5N2 was given a much more powerful engine, and various modifications were made to streamline it. Although its performance was only marginally better, and its weaknesses remained untreated, this version replaced the B5N1 in production and service from 1939. It was this version that would be used by the Navy in the attack on Pearl Harbor. Apart from this raid, the greatest successes of the B5N2 were the key roles they played in sinking the US Navy aircraft carriers Yorktown, Lexington and Hornet.
The B5N served as the basis for a follow-on design, the Nakajima B6N, which eventually replaced it in front-line service. Subsequently, the B5N continued to fly in secondary roles, such as training, target towing, and anti-submarine warfare. Some of the aircraft used for this latter purpose were equipped with early radars and magnetic anomaly detectors. B5Ns were also used as bombers during the unsuccessful defence of the Philippines in October 1944.
Altogether, around 1,150 were built, of which not a single complete example exists today. A large part of a B5N2 was recovered from the Kuril Islands by a British private collector in 2003.