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Japan's Mitsubishi Ki-21 bomber; Army Type 97
Allied code name: originally Jane, later Sally

Photos

Mitsubishi Ki-21 bomber:
Japan's Mitsubishi Ki-21 bomber 		Mitsubishi Ki-21 bomber:
Japan's Mitsubishi Ki-21 bomber		 Mitsubishi Ki-21 bomber:
Japan's Mitsubishi Ki-21 bomber 		Mitsubishi Ki-21 bomber:
Japan's Mitsubishi Ki-21 bomber
Mitsubishi Type 97, OB-97 bomber:
Japan's Mitsubishi Type 97, OB-97 bomber
Aeronautics Aircraft Spotters' Handbook 		Mitsubishi Type 97, OB-97 bomber:
Japan's Mitsubishi Type 97, OB-97 bomber
Aeronautics Aircraft Spotters' Handbook 		   
Mitsubishi Ki-21 bomber:
Japan's Mitsubishi Ki-21 bomber		      

Design

Designed to meet a Imperial Japanese Army Air Force requirement that was given in 19361 / 19382. It was to be a heavy bomber.2 It needed to operate at 6,500' - 13,000', fly 250 mph at 10,000', fly five hours at 187.5 mph, take eight minutes to climb 10,000', and take off in 975'.3

Competition

Both Nakajima and Mitsubishi submitted prototypes and they were tested for six months.3

The military ordered two more prototypes from each company and eventually decided on the Mitsubishi.3

Improvements

In 1939 Mitsubishi was instructed to improve the Ki-21 and they replaced the Ha-6 engine with a Ha-101 engine to give the Ki-21 more performance.1

Prototype

The first Ki-21 prototype first flew in November 19362 / on December 18, 19361,3.

Production

Produced by Mitsubishi and Nakajima.1 Production concluded in September 1944.2

  • Mitsubishi Ki-21: 8:2
  • Mitsubishi Ki-21-I: 7771
  • Mitsubishi Ki-21-Ia, Mitsubishi Ki-21-Ib, Mitsubishi Ki-21-Ic: 7742
  • Mitsubishi Ki-21-Ia:
    • Production: November 1937 - ?3
  • Mitsubishi Ki-21-Ib: 1203
  • Mitsubishi Ki-21-Ic: 1603
  • Mitsubishi Ki-21-II: 42, 1,2781
    • First flew in December 1940.2
  • Mitsubishi Ki-21-IIa: 5902,3
    • Production: December 1940 - ?3
  • Mitsubishi Ki-21-IIb: 6882,3
  • Total: 2,0642,3
    • Manufacturer: Mitsubishi2, Mitsubishi Jukogyo K.K.3, Nakajima2
    • Production: March 1938 - September 19443

Variants

  • Mitsubishi Ki-21: Prototype.2
  • Mitsubishi Ki-21-I: Had Mitsubishi Ha-6 radial engines (850 HP).1 In mid 1938 deliveries started.2
  • Mitsubishi Ki-21-Ia: Enlarged bomb bay.2
  • Mitsubishi Ki-21-Ib: Better armament.3 Increased fuel.3
  • Mitsubishi Ki-21-Ic: Larger wheels.2 Better armament.3 Increased fuel.2,3
  • Mitsubishi Ki-21-II: Had Mitsubishi Ha-101 radial engines (1,500 HP).1 Horizontal tail surfaces were larger.2
  • Mitsubishi Ki-21-IIa: Had a hand held 7.7 mm MG in rear dorsal position.1 Dorsal glasshouse replaced turret.2 Engines with more power.3 Landing gear modified.3
  • Mitsubishi Ki-21-IIb: Had 12.7 mm MG in a turret in the dorsal position.1 Dorsal glasshouse replaced turret.2
  • Mitsubishi MC-21: Transport.2 Converted from Ki-21-Ia in China.2

Usage

Arrival in China

The 60th and 61st Sentai went to China with their Ki-21s in 1938.1,2

Pacific War

The Ki-21 was the main bomber in December 1941.2 It was used in the Malayan, Thai, Burmese, and Netherlands East Indies campaigns.2,3

Secondary Roles

By 1943 the Ki-21 was obsolete and was moved into secondary rolls.2 These included being a bomber trainer, communication aircraft, and a suicide plane.2

Specifications

  Mitsubishi Ki-21 Mitsubishi Type 97
Type Medium bomber2 Long range bomber4
Crew 5 - 72  
Engine (Type)   2: Mitsubishi Kinsei A-144
Cylinders    
Cooling    
Net HP   870 each4
Propeller blades    
Dimensions    
Span 73' 9.75"2
22.5 m2 		85'4
Length 52' 6"2
16 m2 		61'4
Height 15' 11"2
4.85 m2 		 
Wing area    
Weight    
Empty    
Loaded   24,000 lb4
Performance    
Speed   225 mph4
Climb    
Service ceiling    
Range   2,500 miles4
Armament 6: 7.7 mm MG2  
Front   2: MG4
Ventral   2: MG4
Sides   2: MG4
Tail   1: MG4
Normal bomb load 1,653 lb2
750 kg2 		 
Maximum bomb load 2,205 lb2
1,000 kg2 		4,400 lb4
  Mitsubishi Ki-21-I Mitsubishi Ki-21-Ia
Type    
Crew    
Engine (Type) 2: Nakajima Ha-5 Kai2  
Cylinders Radial 142  
Cooling    
Net HP 1,080 each2  
Propeller blades 3 each2  
Dimensions    
Span    
Length    
Height    
Wing area    
Weight    
Empty   10,342 lb2
4,691 kg2
Loaded   17,452 lb2
7,916 kg2
Performance    
Speed @ 13,125' /
4,000 m 		268 mph2
431 kph2 		 
Climb 1,150'/minute2
350 m/minute2 		 
Service ceiling 28,215'2
8,600 m2 		 
Range 932 - 1,678 miles2
1,500 - 2,700 km2 		 
Armament    
  Mitsubishi Ki-21-II Mitsubishi Ki-21-IIb
Type   Bomber1,3
Crew   51,3
Engine (Type) 2: Mitsubishi Ha-1012 2: Mitsubishi Ha-101 piston1,3
Cylinders Radial 142 Radial 143
Cooling   Air3
Net HP 1,500 each2 1,500 each1,3
Propeller blades 3 each2  
Dimensions    
Span   73' 9"3, 73' 9.75"1
22.5 m1
Length   52' 5 7/8"1, 52' 6"3
16 m1
Height   15' 10 7/8"1, 15' 11"3
4.85 m1
Wing area   749.2 ft2 1
69.6 m2 1
Weight    
Empty   13,382 lb1,2
6,070 kg1,2
Loaded   21,362 lb3, 23,391 lb1,2
10,610 kg1,2
Performance    
Speed @ 13,125' /
4,000 m 		  302 mph1
486 kph1
Speed @ 14,485' /
4,720 m 		302 mph2
486 kph2 		 
Speed @ 15,485'   302 mph3
Climb 1,640'/minute2
500 m/minute2 		 
Climb to 19,685' /
6,000 m 		  13.2 minutes1
Service ceiling 32,810'2
10,000 m2 		32,810'1,3
10,000 m1
Range 1,680 miles2
2,700 km2 		1,680 miles1,3
2,700 km1
Armament   6: MG3
Bombs   2,200 lb3

Sources:

  1. Fighting Aircraft of World War II, Editor: Karen Leverington, 1995
  2. Aircraft of WWII, Stewart Wilson, 1998
  3. World War II Airplanes Volume 2, Enzo Angelucci, Paolo Matricardi, 1976
  4. Aeronautics Aircraft Spotters' Handbook, Ensign L. C. Guthman, 1943