Nakajima B5N Kate
The Nakajima B5N, known to the Allies as the Kate, was the Imperial Japanese Navy's standard carrier torpedo bomber of the Pacific War. Designed in the mid-1930s and first flown in 1937, it attacked with a torpedo or with bombs, from carriers and from land bases, and it led the torpedo and high-level bombing at Pearl Harbor in December 1941. Production totalled 1,149 aircraft. Replaced in front-line service in 1944, the type ended the war in secondary roles and kamikaze attacks. No intact example survives; the most complete remains are on display at the Pearl Harbor Aviation Museum.
Why It Mattered
The Nakajima B5N was the Imperial Japanese Navy's standard carrier torpedo bomber through much of the Pacific War, and it doubled as a high-level bomber. The Pearl Harbor Aviation Museum's study of the type calls it the best torpedo bomber in the world at the beginning of that war. The aviation historian René J. Francillon judged the improved B5N2 the most modern aircraft of its type in any navy's service when the war began. In the first year of the war, B5Ns sank or helped sink the American carriers Lexington, Yorktown and Hornet.
Design Notes
Nakajima's prototype first flew in January 1937, and the design won its production contract by outperforming Mitsubishi's competing B5M in trials. It was a clean, single-engine, low-wing monoplane with a folding wing, Fowler flaps, a variable-pitch propeller and a retractable undercarriage. Three crew sat in tandem — a pilot, an observer (teisatsu) and a radio operator who manned the type's single rear gun — and the aircraft carried its torpedo or bombs externally, under the fuselage. The B5N2 improved on the first model with a Sakae 11 radial engine that generated 1,000 hp at takeoff. Protection was traded away for weight and range: the Kate had no armor and no self-sealing fuel tanks, and the museum's study notes that Nakajima could not add armor to the Kate. Production totalled 1,149 aircraft.
Operational History
The B5N1 made its combat debut in the Second Sino-Japanese War in 1938, used there as a level bomber. On 7 December 1941, 144 B5N2s took part in the attack on Pearl Harbor, and the attack's commander, Mitsuo Fuchida, led it from the observer's seat of a Kate. In the first wave, 40 Kates attacked with torpedoes and 49 more with high-level bombs; one of those bombs destroyed the Arizona. A second wave of 54 Kates attacked the airfields instead. Its successor, the B6N Tenzan, replaced the B5N in front-line service during 1944, and the older aircraft moved to secondary work: training, target towing and anti-submarine patrols. As losses mounted, the type also shifted to rear-area sea lane control duties in 1944. B5Ns flew as bombers in the defence of the Philippines in October 1944 and suffered severe losses there. In the war's closing months, most of the B5Ns that remained were expended in kamikaze attacks.
Afterlife
No B5N survived the war intact; only two partially recovered aircraft are known to exist, and neither is airworthy. The more complete survivor is the B5N2 with the tail number 302, among the last aircraft still airworthy at Vunakanau airfield near Rabaul when the war ended; it was abandoned at Jacquinot Bay Airfield after its surrender flight. The Pearl Harbor Aviation Museum acquired the remains and, deciding to display the aircraft in its original, largely unrestored condition, put it on display in Hangar 37 in 2018, still missing much of its aft fuselage and its left outer wing. In 2025 the museum installed a newly built outer wing panel on the port side; with both wings fitted, the aircraft is the most complete B5N on public display. The second survivor is a hulk recovered from the Kuril Islands in 2003, now on display at the Wings Museum in Britain. The Kates familiar from airshows are not originals: no B5N existed in flyable condition when the film Tora! Tora! Tora! was made, so Harvard Mark IV trainers were converted into Tora Kates. The Kate replicas were the most heavily modified of the film's aircraft, with fuselage extensions, modified BT-13 tails and reshaped wings, and after filming they found a second life in airshows.