B5N

B5N. The Nakajima B5N, codenamed "Kate" by the Allies of World War II, was the standard torpedo bomber of the Imperial Japanese Navy Air Service for much of the Second Sino-Japanese War and the early years of the Pacific War. Although obsolescent by the time of the attack on Pearl Harbor, its well-trained aircrews and effective aerial torpedo tactics made it a devastatingly successful weapon in the opening campaigns. The type served in every major naval engagement from the Battle of the Coral Sea to the Battle of the Philippine Sea, but suffered heavy losses as the war progressed against increasingly potent United States Navy fighter aircraft and anti-aircraft warfare.

Development and design

The B5N was developed to meet a 1935 specification from the Imperial Japanese Navy for a modern carrier-based attack aircraft to replace the aging Yokosuka B4Y. The design team at the Nakajima Aircraft Company, led by Katsuji Nakamura, created a low-wing monoplane with an all-metal structure, featuring retractable landing gear and enclosed cockpits for its three-man crew. It was initially powered by the Nakajima Hikari radial engine, which provided adequate performance but was later deemed insufficient. The aircraft's most significant design feature was its ability to carry either a single Type 91 torpedo or an equivalent bomb load, making it a versatile platform for attacking capital ships. The prototype first flew in January 1937, demonstrating superior performance to its predecessor and entering service later that year with the Imperial Japanese Navy Air Service.

Operational history

The B5N first saw combat in the Second Sino-Japanese War, performing level bombing missions with some success. Its defining moment came during the attack on Pearl Harbor on December 7, 1941, where B5N2 models, armed with modified aerial torpedoes, crippled the U.S. Pacific Fleet by sinking or damaging multiple battleships, including the USS Arizona (BB-39) and USS Oklahoma (BB-37). The type played a central role in subsequent Japanese victories, delivering fatal blows to the British Eastern Fleet at the Indian Ocean raid and sinking the USS Lexington (CV-2) at the Battle of the Coral Sea and the USS Hornet (CV-8) at the Battle of the Santa Cruz Islands. However, during the Battle of Midway, unescorted B5Ns were decimated by Grumman F4F Wildcat fighters, contributing to the pivotal Japanese defeat. By 1944, the vulnerable "Kate" was relegated to secondary duties, including anti-submarine warfare and night attacks, as it was replaced by the more advanced B6N.

Variants

The primary production variant was the initial **B5N1**, which entered service powered by the 770 hp Nakajima Hikari 3 engine. Its shortcomings in speed and altitude performance led to the development of the definitive **B5N2**, which was fitted with the more powerful 1,000 hp Nakajima Sakae 11 radial engine, the same engine used in the Mitsubishi A6M Zero. This upgrade improved overall performance but did not address the aircraft's lack of defensive armor or self-sealing fuel tanks. A handful of **B5N1-K** and **B5N2-K** trainer variants were produced, with dual controls for instructing pilots. Experimental versions included aircraft tested with Mitsubishi Kinsei engines and others modified for specialized roles, such as electronic warfare or as motherplanes for the MXY7 Ohka piloted bomb late in the war.

Operators

The primary and essentially sole military operator was the Imperial Japanese Navy Air Service, which deployed the B5N from nearly all its aircraft carriers, including the Akagi, Kaga, and Shōkaku-class aircraft carrier. Land-based units also operated the type from airfields across the Japanese empire, including in China, the Dutch East Indies, and the South Pacific Mandate. Following Japan's surrender in 1945, a small number of captured aircraft were evaluated by the United States Army Air Forces and the Soviet Air Forces, but none saw operational service with these powers. No B5Ns were transferred to allied nations such as the Kingdom of Thailand or the Reorganized National Government of China.

Specifications (B5N2)

* **Crew:** 3 (pilot, navigator/bombardier, radio operator/gunner) * **Length:** 10.3 m (33 ft 10 in) * **Wingspan:** 15.518 m (50 ft 11 in) * **Height:** 3.7 m (12 ft 2 in) * **Empty weight:** 2,279 kg (5,024 lb) * **Max takeoff weight:** 4,100 kg (9,039 lb) * **Powerplant:** 1 × Nakajima Sakae 11 14-cylinder air-cooled radial engine, 750 kW (1,000 hp) * **Maximum speed:** 378 km/h (235 mph, 204 kn) at 3,600 m (11,800 ft) * **Range:** 1,991 km (1,237 mi, 1,075 nmi) * **Service ceiling:** 8,260 m (27,100 ft) * **Armament:** 1 × rear-firing 7.7 mm Type 92 machine gun * **Bombs:** 1 × 800 kg (1,764 lb) Type 91 torpedo **or** 3 × 250 kg (551 lb) bombs **or** 1 × 800 kg armor-piercing bomb

Category:Military aircraft of Japan Category:Torpedo bombers Category:World War II Japanese aircraft