Nakajima B5N KATE
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Nakajima B5N KATE

Designed to a 1935 requirement, and already in service for four years when Japan entered the war, the Nakajima B5N was in 1941 without question the best carrierborne torpedo-bomber in the world. Powered by a Nakajima Hikan radial engine, the low-wing three-crew monoplane with inwards-retracting wide-track landing gear was exceptionally clean, and first flew in January 1937. The following year production B5N1 aircraft were embarking in Japan's carriers and shore-based units were deployed in China. In 1939 the improved B5N2 appeared with a more powerful Sakae 11 engine in a smaller cowling, although armament and bombload were unchanged, and this version remained in production until 1943. When Japan attacked the USA the B5N2 had wholly replaced the B5N1 with operational units, and 144 B5N2s were involved in the fateful attack on Pearl Harbor; within the next 12 months aircraft of this type sank the American carriers USS Hornet, Lexington and Yorktown. Given the reporting name 'Kate' by the Allies, the B5N certainly earned the respect of the Americans, and in all the major carrier battles of the Pacific War attracted the undivided attention of defending fighters. With its puny defensive armament of a single machine-gun and laden with a large bomb or torpedo, however, the B5N began to suffer very heavily, and although the type was fully committed during the Solomons campaign the survivors were withdrawn from combat after the Philippine battles of 1944. Thereafter, on account of their excellent range, they were assigned to antisubmarine and maritime reconnaissance duties in areas beyond the range of Allied fighters. Production of all B5Ns reached 1,149.

Nakajima B5N KATE

 ENGINE1 x Nakajima NK1B "Sakae", 746kW
    Take-off weight4100 kg9039 lb
    Empty weight2279 kg5024 lb
    Wingspan15.52 m51 ft 11 in
    Length10.3 m34 ft 10 in
    Height3.7 m12 ft 2 in
    Wing area37.7 m2405.80 sq ft
    Max. speed378 km/h235 mph
    Ceiling8260 m27100 ft
    Range w/max.fuel1990 km1237 miles
 ARMAMENT1 x 7.7mm machine-guns, 800kg of bombs

Nakajima B5N KATEA three-view drawing (752 x 870)

Ed Wagamon, 19.01.2015

[The Kate wasn't a bad level bomber either, to which the survivors (and not) of the USS Arizona can personally attest. Kates accounted for a number of USN and Royal Navy capital ships during the war, with bombs, not just torpedoes. –wag]

Ed Wagamon, 19.01.2015

[It wasn't just them—EVERYBODY in the mid to late-1930s (when this generation of planes was being designed and fielded) thought that a single, rifle-caliber machinegun would be good enough, as the world was just then getting out of the biplane era, and front-line fighters just entering, or about to enter service were also still equipped with only a pair or maybe 4 rifle-caliber machineguns, with few exceptions (the Italian CR.32, which had 2x 12.7mm), and the Americans, which mixed a single .30 cal with a .50 cal on many of their designs that saw service during that period (P-26, Hawk III, P-36A, P-40A, P-35), and the Brits, which at least put 4, then 8 .303" mgs in their Hurricane and prototype Spitfire, but even they went to war with the biplane Gladiator. The Germans also had only 7.9mm mgs in their He-51, as well as early Bf-109s of that time frame (The Spanish Civil War was just getting really going in 1937, and the "Nomohan" conflict between the Soviets and Japan was also just occurring, so there were few "combat lessons" to be had by the world's air forces, and thus, WWI methods and practice still prevailed. Even later on, our own SBD Dauntless, SBU Vindicator, and other light attack aircraft, just like the Fairey Battle, Bristol Blenheim, Ju-87 Stuka, and Soviet BB-1, Su-2, Su-4, and Su-6 and SB bombers that fought in the conflicts of the late 1930s and early years of WW2 all had only single, rifle-caliber defensive guns to protect them. Twin rifle-caliber mounts persisted through the early war years, some through the end of the war—Later Blenheims had twin .303's, ad did many Brit and Soviet light bombers, as well as the Ju-87 Stuka from '42 on. Though the US Navy Dauntless began the war with only a single rear .30 cal mg, the US Navy's SBD Dauntless and SB2C Helldiver had only twin .30 cal guns from 1942 to the end of the war. It was "just the way it was"— a single, man-handled gun mount had to be light enough for the gunner to handle in a slipstream, and that meant that many rifle-caliber mounts served long after they were all but useless. But again, "all but useless" is not "utterly useless" – even famed Japanese Navy Ace Saburo Sakai was nearly killed by return fire from a Dauntless' rear gunner, and was out of action for more than a year, and blind in one eye afterwards. No fighter pilot wants even .30 caliber bullets shot into his engine or other parts of his plane! --wag]

David, 01.12.2014

I always love how they list the bomb load as 800 kg when only one of all the versions of IJN 45cm Aireal Torpedoes weighed under 800kg, the rest weighing in between 850kg and 1100kg. The B5N, B6N, and B7A all had at least a 1000kg bomb load.

Grummancat, 01.09.2014

@ Klaatu83

Hell, the Fairey SWORDFISH was far superior to the Devastator LOL

Klaatu83, 22.06.2013

The B5N was a very effective torpedo-bomber, with far superior performance to the Douglas TBD Devastator and Fairey Barracuda. However, it's excellent speed and range performance was gained at the expense of defensive armament, as well as of armor protection for the crew and fuel tanks. That state of affairs would not have been deemed acceptable in similar aircraft operated by either the Royal Navy or the U.S. Navy.

beifang, 21.06.2011

This plane was FAR FAR superior, as a carrier based bomber, than the 'opposition' (Blackburn Roc. Vought Vindicator etc)...did a helluva lot of damage to enemy ships too!

, 21.06.2011

Nakajima B5N KATE

sultan, 17.04.2011

it was later armed with type 97 machineguns making it good at keeping fighters away, it was a very long leap ahead of its counterparts (fairey albcore, fairey swordfish, TBD devestator, etc) the plane was considrably fast, sank alot of allied ships and served potently as kamikaze.

JesMe, 11.04.2011

Kates didn't carry Long Lances, those were shipboard-only weapons. The Kate couldn't carry that much weight.

Klaatu83, 04.03.2011

Roughly contemporary to, and unquestionably better than, the U.S. Navy's Douglas Devastator. Even worse, at the time Japanese Navy pilots were flying these, the Royal Navy was introducing the Fairey Swordfish. What were the British thinking!

DebtMan, 12.11.2010

The name of the motor is Hikari,not Hikan

Zach, 18.10.2010

The Kate is a well-desigened torpedo-bomber. The only reason it failed to do so much was lack of adequate support and only a handful of aircraft.

David, 10.09.2010

Well, the tactics were to cover the torpedo bombers with a screen of fighters. To add heavy defensive armament would simply reduce range.

john, 09.03.2010

what an alsome bomber

Mike, 02.03.2010

Not only was this the best torpedo bomber but if it carried the 21 inch Long Lance it was carrying the best torpedo in the world. Any drawings available

carlyne, 11.11.2009

i really think that this kate was a good choice of the japs to use to attack pearl harbor with.

Ernie, 01.02.2009

Is there any resource that would include a more complete 3 view, showing bulkheads, etc.?

Thank You!

Mick Dunn, 23.11.2008

Bugger the popgun defence armament! This plane was FAR FAR superior, as a carrier based bomber, than the 'opposition' (Blackburn Roc. Vought Vindicator etc)...did a helluva lot of damage to enemy ships too!

Xiaohan, 18.10.2008

How do the japs expect a 7.7mm machine gun to defend a 378km/h plane that is heavily laden with a torpedo. Even the B6N2 with a single 13mm machine gun was useless.

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