World War II Database

Contributor: C. Peter Chen

ww2dbaseThe B4Y carrier torpedo planes were designed by Sanae Kawasaki at the First Naval Air Technical Arsenal at Yokosuka, Japan as the response to the 1932 and 1934 Japanese Navy requirements for a new torpedo bomber to replace the aging B3Y design. These new biplanes had metal structures and mixed metal-fabric skin; they were each manned by a crew of three, with the pilot in the open front cockpit and the navigator and the radio operator/gunner in the enclosed rear cockpit. After the naval arsenal in Yokosuka produced the first five prototypes, production responsibilities were given to Nakajima (built 37 between 1937 and 1938), Mitsubishi in Nagoya (built 135 between 1937 and 1938), and the 11th Naval Air Arsenal in Hiro (built 28 in 1938); a total of 205 aircraft were built. They were equipped aboard carriers Akagi, Hosho, Kaga, Ryujo, Soryu, and Unyo, and with the ground-based 13th and 15th Air Groups. At the opening chapters of the Second Sino-Japanese War, B4Y1 biplanes were the aircraft responsible for the attack of gunboat USS Panay in Nanjing, China on 12 Dec 1937. They remained primary carrier torpedo bombers of the Japanese Navy until 1940 when they were replaced by the B5N design. Between 1940 and 1943, they were largely relegated to the rear as trainer aircraft, with the exception that they remained aboard Hosho and Unyo. Those aboard Hosho participated during the Battle of Midway.

ww2dbaseThe Allied codename for this aircraft was "Jean".

SPECIFICATIONS

B4Y

Machinery	One Nakajima Hikari-2 9-cyl air-cooled radial engine rated at 840hp
Armament	1x7.7mm rear Type 92 machine gun, 1x800kg torpedo or 500kg of bombs
Crew	3
Span	15.00 m
Length	10.15 m
Height	4.36 m
Wing Area	50.00 m²
Weight, Empty	2,000 kg
Weight, Loaded	3,600 kg
Speed, Maximum	278 km/h
Service Ceiling	6,000 m
Range, Normal	1,575 km

Photographs