Yokosuka B4Y

Infobox Aircraft
name = B4Y1
type = Torpedo bomber
manufacturer = Yokosuka


caption =
designer =
first flight = 1935
introduced = 1936
retired = 1943
status =
primary users = IJN Air Service
more users =
produced =
number built = 205
unit cost =
variants with their own articles =

The Yokosuka B4Y, (Navy Type 96 Carrier Attack Plane), carrier attack aircraft was used by the Imperial Japanese Navy Air Service] from 1936 to 1943. The B4Y replaced the Mitsubishi B2M2 and was the last bi-plane bomber used operationally by the Imperial Japanese Navy . The Allied reporting name was "Jean".

Design and development

In 1932 the Imperial Japanese Navy issued a requirement for a new carrier-borne attack aircraft. Aichi, Mitsubishi and Nakajima, responded to this requirement and each built prototype aircraft. Neither of these aircraft were deemed satisfactory, and the service thus issued a 1934 requirement for a more capable aircraft to replace the obsolescent Yokosuka B3Y.

The B4Y was designed by Sanae Kawasaki at the First Naval Air Technical Arsenal at Yokosuka. Regarded only as an interim type, the Japanese Imperial Navy wanted a torpedo bomber offering performance comparable to the Mitsubishi A5M monoplane fighter. The result was a bi-plane with fixed landing gear and an all-metal structure with metal or fabric skin. To speed development and production, the B4Y utilised the wings from the Kawanishi E7K.

The B4Y1 was also the first Imperial Japanese Navy carrier attack aircraft to utilize an air-cooled engine.

The crew of three occupied two cockpits. The Pilot in the open front cockpit and the other two crewmen, (Navigator and Radio operator/Gunner), in the enclosed rear cockpit.

Operational Service

Although primarily used as a carrier-based aircraft, the B4Y1 was also used as a land-based bomber on occasion. In 1940 the Nakajima B5N replaced the B4Y1 as the primary carrier attack aircraft, though the B4Y1 did remain in service as an advanced trainer, and flew from the carriers "Hōshō" and "Unyo" until 1943.Before its replacement the B4Y1 had flown during the Second Sino-Japanese War and did serve at the Battle of Midway during June 1942, where eight of them were operated from the aircraft carrier "Hōshō".It was one of these planes from "Hōshō" which took photographs of the burning carrier "Hiryū" on June 5, 1942.

The B4Y1 was operated from the aircraft carriers "Akagi", "Hōshō", "Kaga", "Ryūjō", "Sōryū", and "Unyo"; as well as several land based air groups.

Variants

*First Prototype: 750 hp Hiro Type 91 twelve cylinder liquid cooled engine driving a two-bladed propeller.
*Second and Third Prototypes: Engine 640 hp Nakajima Kotobuki-3 nine-cylinder air-cooled radial driving a two-bladed propeller.
*Fourth and Fifth Prototype and Production Aircraft: Engine 840 hp Nakajima Hikari-2 nine-cylinder air-cooled radial driving a two-blade propeller.

Production

*205 Total
*Dai-Ichi Kaigun Koku Gijitsusho, Yokosuka: 5 prototypes (1935-36).
*Nakajima Hikoki K. K.: 37 production aircraft (1937-38).
*Mitsubishi Jukogyo K. K., Nagoya: 135 production aircraft (1937-38).
*Dai-Juichi Kaigun Kokusho, Hiro: 28 production aircraft (1938).

Operators

;JPN
*Imperial Japanese Navy Air Service

pecifications

aircraft specification|
plane or copter?=plane |jet or prop?=prop
crew=3 (pilot, navigator, radio operator/gunner)
length main=10.15 m
length alt=33.3 ft
span main=15.0 m
span alt=14.2 ft
height main=4.36 m
height alt=14.3 ft
area main=50 m²
area alt=548 ft²
empty weight main=2,000 kg
empty weight alt=4,400 lb
loaded weight main=
loaded weight alt=
max takeoff weight main=3,600 kg
max takeoff weight alt=7,900 lb
more general=
engine (prop)=Nakajima Hikari-2
type of prop=9-cylinder radial engine
number of props=1
power main=626 kW
power alt=840 hp
max speed main=278 km/h
max speed alt=173 mph
max speed more=
range main=1580 km
range alt=980 mi
ceiling main=6,000 m
ceiling alt=19,700 ft
climb rate main=3.6 m/s
climb rate alt=710 ft/min
loading main=72 kg/m²
loading alt=14.8 lb/ft²
power/mass main=291 W/kg
power/mass alt=0.19 hp/lb
more performance=
armament=1 x 7.7 mm (0.303 in) flexible rear-firing Type 92 machine gun 1x800 kg torpedo, or 500 kg of bombs.

References

* Francillon, R. "Japanese Aircraft of the Pacific War." Naval Institute Press, 1987.
* "English Translation of Kojinsha No. 6 Warships of the Imperial Japanese Navy."aircontent
related=
similar aircraft=
lists=
List of military aircraft of Japan