Mitsubishi Ki-21

The Mitsubishi Ki-21 was a Japanese heavy bomber during World War II.

It began operations during the Second Sino-Japanese War participating in the Nomonhan Incident, and in the first stages of the Pacific War, including the Malayan, Burmese, Dutch East Indies and New Guinea Campaigns.

It was also used to attack targets as far-flung as western China, India and Northern Australia.



Prototype models with various engines and armament combinations for evaluation.

Final version with Nakajima Ha-5 engine. 8 built

Ki-21-Ia (Army Type 97 Heavy Bomber, Model IA)

First production model, with 634 kW (850 hp) Nakajima Ha-5-kai engines.

Most were built by Mitsubishi, 143 manufactured by Nakajima

Ki-21-Ib (Army Type 97 Heavy Bomber, Model IB)

Improved version with additional 7.7 mm (.303 in) machine guns, larger bomb compartment and flaps, redesigned tail.

120 built by Mitsubishi, 351 (including Ki-21 Ib and Ic) by Nakajima

Ki-21-Ic (Army Type 97 Heavy Bomber, Model IC)

Improved type with one additional 7.7 mm (.303 in) machine gun, increased fuel capacity, 160 built by Mitsubishi


Evaluation model with more powerful engines, 4 built

Ki-21-IIa (Army Type 97 Heavy Bomber, Model IIA)

Production model based on Ki-21-II, 590 built

Ki-21-IIb (Army Type 97 Heavy Bomber, Model IIB)

Final production version based on Ki-21-IIa with modified canopy, clear upper cabin replaced by rotating turret, 688 built.

MC-20-I (Army Type 100 Transport, Model I)

Unarmed civilian transport version, converted from Ki-21-Ia; approximately 100 aircraft were converted





16 m (52 ft 6 in)


22.5 m (73 ft 10 in)


4.85 m (15 ft 11 in)

Wing area

69.9 m2 (752 sq ft)

Empty weight

6,070 kg (13,382 lb)

Gross weight

10,600 kg (23,369 lb)


2 × Mitsubishi Ha101 14-cylinder air-cooled radial piston engine, 1,100 kW (1,500 hp) each (long designation Army Type 100 1,450hp Air Cooled Radial)


3-bladed variable-pitch propellers


Maximum speed

485 km/h (301 mph, 262 kn)

Cruise speed

380 km/h (240 mph, 210 kn)


2,700 km (1,700 mi, 1,500 nmi)

Service ceiling

10,000 m (33,000 ft)

Time to altitude

6,000 m (19,685 ft) in 13 minutes 13 seconds



5× 7.7 mm (.303 in) flexible Type 89 machine guns in nose, ventral, beam and tail positions

1× 12.7 mm (.50 in) Ho-103 machine gun in dorsal turret


1,000 kg (2,200 lb) of bombs.


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