Mitsubishi B2M Type 89 carrier attack bomber/ Mitsubishi 3MR4/ Blackburn T.7B

The Mitsubishi B2M was a Japanese biplane torpedo bomber designed by Blackburn Aircraft in Britain in response to a request from Mitsubishi for designs to replace their own B1M1 Type 13 carrier attack bomber. When the Imperial Japanese Navy decided to replace the B1M Mitsubishi responded by requesting basic designs from Herbert Smith, with whom they had worked in the past, from Handley Page and from Blackburn. The new aircraft was to be powered by a Hispano-Suiza Type 51-12Lb 600hp twelve cylinder water cooled engine, for which Mitsubishi had purchased a manufacturing licence.

The new aircraft ended up with a number of different designations. To Blackburn it was the T.7B, or seventh in their series of torpedo bombers. In Japan it was the 3MR4, the B2M and the Type 89 carrier attack bomber. The 3MR4 designation referred to its primary duty (No.3, torpedo bomber), manufacturer (Mitsubishi), secondary duty (Reconnaissance) and to its position as the fourth torpedo bomber in this system. B2M came from the famous short designation system, making it the second carrier attack bomber, and Type 89 from 1929, the year in which the design was accepted.

Blackburn submitted the T.7, a very large aircraft similar to the Blackburn Beagle. Their prototype was powered by a 625hp engine Hispano-Suiza Type 51-12Lbr. It was a two bay biplane with staggered wings of unequal length. All four wings had Frise ailerons and Handley Page leading edge slots. The aircraft had a metal framework, with fabric covered wings and rear fuselage and aluminium panels from the front of the fuselage to a position to the rear of the cockpit. Most of the fabric covered area was filled with flotation bags.

The Blackburn design was accepted by Mitsubishi, and by the Japanese Navy. It carried three men in its reconnaissance role - pilot, wireless operator/ bomb-aimer, observer/ gunner – in three separate but close cockpits, or two men when used as a torpedo bomber. The prototype was completed in November 1929, made its maiden flight on 28 December 1929, and on 3 January 1930 was crated up ready to be shipped to Japan.

B2M1 Type 89 Model 1

The first version of the B2M was armed with four guns – a fixed Vickers gun mounted on the port side of the front fuselage, twin Lewis guns on double mountings over the observer’s cockpit, and provision for a fourth gun to be fired down through the hole left for the bomb sight. It could carry a 2,000lb torpedo with 100 gallons of fuel or two 250lb bombs and 202 gallons of fuel. Licence built machines had a 650hp Mitsubishi-Hispano Type 7 engine, a more rounded tail, smaller elevator horn balances and a slimmer nose with a retractable radiator. Deliveries began in 1933.

B2M2 Type 89 Model 2

The second production version of the B2M had shorter wings, a slimmer nose, a triangular fin and rudder, and only carried two guns. It could carry 1,764lb of bombs over a short range, or the same combination of bombs or torpedoes as the B2M1. Production ended in 1935.

A total of 205 B2M1s and B2M2s were produced in Japan. They served on the aircraft carriers Ryujo, Akagi and Kaga from 1933 to 1937, and on the Japanese mainland with the Tateyama Air Corps. They were also used as carrier training aircraft.





Mitsubishi-Suiza Type 51-12Lbr



Upper span

48ft 9in

48ft 0in

Lower span

49ft 11in

49ft 1in


33ft 7in

33ft 5in


10ft 4in

11ft 8in

Tare weight



All-up wieght



Speed at sea level



Cruising speed



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How to cite this article: Rickard, J (8 December 2008), Mitsubishi B2M Type 89 carrier attack bomber/ Mitsubishi 3MR4/ Blackburn T.7B,

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