Nakajima B5N torpedo-bomber - derived and modified with thanks from an illustration in 'Jane's War at Sea: Centennial Edition' (Jane's Publishing)

Nakajima B5N - 'Kate'


TheNakajima B5N - Allied reporting-name 'Kate' - was the sole shipboard torpedo-bomber of the Japanese Navy at the start of the Pacific War. It was by then quite old, having been designed to meet a specification of 1935, and was already judged to be obsolescent.  However, when first put into production it had been a very advanced aircraft,  and in war it out-performed any Allied shipborne torpedo-plane until the arrival of the Grumman Avenger in mid-1942. In particular it was greatly superior to the Douglas TBD Devastator - the carrier-borne torpedo-plane of the US Fleet at the Battle of the Coral Sea and the decisive Battle of Midway.
B5Nsplayed the main role in sinking the carrier Lexington at Coral Sea, Yorktown at Midway, and Hornet at the Battle of Santa Cruz in October 1942. Along with the destruction of the carrier Wasp by a Japanese submarine during the Guadalcanal campaign these were the major blows to the American carrier forces in the early phase of the Pacific War.  These exploits supplemented the Kate's success in the surprise attack on Pearl Harbor on December 7 1941,  in which 40 B5N2s armed with torpedoes - and 103 B5N2s armed with bombs - inflicted enormous damage on the US Battle Fleet.

Total production of the B5N was 1,149 units.  By the time of the Marianas campaign it had been largely replaced by its successor - the Nakajima B6N Tenzan - but at the huge air-sea Battle of the Philippine Sea there were 17 Kates in Admiral Ozawa's Mobile Fleet,  aboard the ships of  Carrier Division Three.


Nakajima B5N 'Kate'

Origin Nakajima-Nikoki KK

Type (B5N1) Three-seat carrier-based bomber  - (B5N2) Three-seat carrier-based torpedo-bomber

Dimensions Span 50' 11" -  Length 33' 10" -  Height 12' 2"

Weights  (B5N1) 4,645 lb empty, 8,047 lb loaded
(B5N2) 5,024 lb empty, 8,378 lb loaded (normal), 9,039 lb loaded (maximum).

(B5N1) One 770 hp Nakajima Hikari 3 9-Cylinder radial
(B5N1 Model 12 ) 970 hp or 985 hp Sakae 11 14-Cylinder 2-row radial
(B5N2) 1,115 hp Sakae 21 radial

Maximum speed  (B5N1) 217 mph  -  (B5N2) 235 mph
Initial climb:  1,378 feet per minute
Service ceiling:  Approx 25,000 feet
Range:  (B5N1)  683 miles (B6N2 with normal load) 609 miles.

(B5N1)  One 7.7 mm machine-gun, manually-aimed, in rear cockpit
Underwing racks for two 250 kg bombs or six 60 kg bombs
(B5N2)  Twin 7.7 mm machine-guns, manually-aimed, in rear cockpit
 plus (?) two 7.7 mm machine-guns, fixed, above forward fuselage (?)
(These two forward-firing guns are given in Bill Gunston's 'Combat Aircraft of World War Two'
but they are not referred to in other sources)
Fuselage rack for one 800 kg (18-inch) torpedo or three 250 kg bombs


Nakajima B6N2 Tenzan - reproduced with thanks from D Mondey 'Axis Aircraft of World War II' (Chancellor Press)

Nakajima B6N Tenzan

The B6N, although a conventional-looking aircraft, was in some respects superior to contemporary Allied torpedo planes. Known as the Tenzan ('Heavenly Mountain'), it was a slender and clean-lined machine with no internal weapons bay.  The torpedo was carried offset to the right,  with the large oil cooler offset to the other side.  The big Mamori engine of the B6N1, driving a four-blade Hamilton-type propeller, underwent severe vibration and overheating. Although it was kept in service it was replaced in production by the the B6N2.  The lower power of the older and well-tried Kasei engine was compensated for by improved streamlining, which produced less drag.

Tenzans went into action for the first time in late 1943, off Bougainville in the Solomon Islands.  At the huge air-sea Battle of the Philippine Sea the air complement of the Mobile Fleet's carriers included some 80 B6Ns. Towards the end of the war some Tenzans were equipped with radar for night torpedo attacks on Allied shipping. Additionally, many Jills were employed in kamikaze attacks on the US fleet, especially during the Okinawa campaign in April and May of 1945.

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Nakajima B6N Tenzan - 'Jill'

Origin:  Nakajima Hikoki KK

Type:  Three-seat carrier-based and land-based torpedo-bomber

Dimensions:  Span 48' 10" - Length 35' 8" - Height (B6N1) 12' 2" (B6N2) 12' 6"

Weight:  6,636 lb empty,  11,464 loaded (normal)  12,456 loaded (maximum)


 (B6N1)  One 1,870 hp Nakajima Mamori-11 14-cylinder two-row radial
(B6N2)  One 1,850 hp Mitsubishi Kasei-25 14-cylinder two-row radial


One 7.7 mm machine-gun, manually-aimed, in rear cockpit
One 7.7 mm machine-gun manually-aimed by middle crew member, in rear ventral position
One 800 kg (17.7-inch) torpedo  or six 100 kg bombs under fuselage


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The above data are derived mainly from Bill Gunston's 'Combat Aircraft of World War II'  (Salamander, London 1978), The profile drawing of the B5N at the head of this page is reproduced,  with thanks, from

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