Mitsubishi B1M

The Mitsubishi B1M was a Japanese torpedo bomber of the 1920s, also known as the Navy Type 13 Carrier-Borne Attack Aircraft. It was designed and built by Mitsubishi and used in combat against China.

Mitsubishi B1M
Class Aircraft
Type Bomber
Manufacturer Mitsubishi Aircraft Corporation
Origin Japan
Country Name Origin Year
Japan 1923
Country Name Operational Year Retirement Year
Japan 1924 1932 View
ManufacturerName Production From Production To Quantity
Mitsubishi Aircraft Corporation 443 View
While working with the Mitsubishi company, the British aircraft designer Herbert Smith designed the 2MT1 two-seat biplane torpedo bomber which flew for the first time in January 1923. It went into Japanese Navy service as the Type 13-1 carrier-borne attack aircraft or B1M1, and was followed by the 2MT2 and 2MT3 variants (also designated B1M1). The redesigned Type 13-2 was designated B1M2. The final version, the Type 13-3 or B1M3, had the company designation 3MT2 and was a three-seater. Total production was 443. The B1M was powered by a 335 kW Napier Lion or Hispano-Suiza engine according to version.

The type entered service in 1924 and served into the 1930s, 32 flying from the aircraft carriers Kaga and Hosho during the Shanghai Incident in 1932. An aircraft from Kaga was lost during an aerial engagement between an American air force adviser and demonstration pilot to the Chinese government, Robert Short, who also lost his life, and regarded as a hero defending the Chinese city against the Japanese aircraft.

From 1929, a number of surplus B1Ms were converted for civilian use, being fitted with an enclosed cabin for passengers or cargo.

Role Torpedo bomber
Manufacturer Mitsubishi
First flight 1923
Introduction 1924
Primary user Imperial Japanese Navy
Number built 443
Variants Mitsubishi 2MB1

General characteristics

  • Crew: Two
  • Length: 9.77 m (32 ft 0 in)
  • Wingspan: 14.77 m (48 ft 5 in)
  • Height: 3.50 m (11 ft 5 in)
  • Wing area: 59.0 m (645 ft)
  • Empty weight: 1,442 kg (3,179 lb)
  • Max takeoff weight: 2,697 kg (5,946 lb)
  • Powerplant: 1 x Napier Lion 12 cylinder broad arrow engine, 373 kW (500 hp)


  • Maximum speed: 210 km/h (113 knots, 130 mph)
  • Range: km (nm, mi)
  • Service ceiling 4,500 m (14,765 ft)
  • Wing loading: 45.7 kg/m (9.22 lb/ft)
  • Power/mass: 0.14 kW/kg (0.084 hp/lb)
  • Endurance: 2.6 hours


  • Two fixed forward firing 7.7 mm machine guns and two pivoted 7.7 mm machine guns in rear cockpit
  • One 18 inch torpedo or two 240 kg (529 lb) bombs

End notes