Mitsubishi B2M1 (1927)

Carrier based Torpedo Bomber (1927), 48 made 1927-1930

In 1925, the Japanese Army Aviation Command (Rikugun Kokubu) announced a competition for the creation of a light bomber to replace the obsolete licensed French biplane Salmson 2A2, produced in Japan under the short designation Otsu 1. Army requirements provided for a qualitatively new aircraft capable of lifting large-caliber bombs. The aircraft was intended for the tasks of reconnaissance, communications, creating smoke screens and, of course, bombing. Naturally, the flight characteristics should have been qualitatively higher. The proposal was sent to three companies: Nakajima, Kawasaki and Mitsubishi.

The Mitsubishi firm used the services of the German engineer and Stuttgart Alexander Baumann. Under his leadership, a 2MB2 "Washi" biplane was designed. However, despite the innovative design, it was rejected by the army due to its too high cost. In return, it was proposed to adapt the Type 13 - B1M carrier-based torpedo bomber for the army (factory designation 2MT1).

Between March 1926 and March 1927, four copies of the prototype were built. They replaced the original Napier "Lion" engine with a more powerful water-cooled Hispano-Suiza V-12. The side radiators of the "marine" variant were replaced by one large frontal radiator, in connection with which the aircraft acquired a characteristic "blunt" nose shape compared to the B1M. Folding wings, not needed for the land version, became fixed. Armament consisted of four 7.7 mm Vickers machine guns. - one synchronous forward and two in the defensive turret at the shooter and one in the lower hatch installation. Bomb load up to 500 kg on an external sling under the fuselage. Crew 2 people.

The upgraded version was designated the 2MB1 or "Type 87 light bomber (Hachinana-shiki Keibakugekiki)" and put into production as such. December 1927. Some were sent to training bases at Hamamatsu and Kakamigahara.

Mitsubishi Type 87 bombers took part in the fighting in Manchuria in 1932 and throughout the entire period of the Sino-Japanese struggle for dominance in Manchuria. In 1934, the gradual withdrawal of the Type 87 from combat units and their replacement by twin-engined Mitsubishi Ki-2s began. The total number of Type 87 2MB1 bombers produced was 48.

Detailed specs

B1M-1 1924
Crew:	2: Pilot, Observer (3 on B1M3)
Fuselage Lenght	9.77 m (32 ft 1 in)
Wingspan	3.5 m (48 ft 5 in)
Wing area	59 m2 (640 sq ft)
Height	3.5 m (11 ft 6 in)
Empty weight:	1,442 kg (3,179 lb)
Max takeoff weight:	2,697 kg (5,946 lb)
Powerplant:	Napier Lion W-12 water-cooled piston engine, 370 kW (500 hp)
Propellers:	2-bladed fixed-pitch propeller
Maximum speed:	210 km/h (130 mph, 110 kn)
Endurance:	2,6 hours
Service ceiling:	4,500 m (14,800 ft)
Wing Loading:	45.7 kg/m2 (9.4 lb/sq ft)
Power/mass:	0.14 kW/kg (0.085 hp/lb)
Armament	Guns: 2 fixed, 2 rear 7.7mm machine guns, 1 Torpedo, 240 kgs bombs