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Nakajima Ki-49 Donryu (Helen)

Medium Bomber Aircraft

The Nakajima Ki-49 Donryu was destined to replace the ill-equipped Ki-21 though the Ki-49 itself was a general failure in design.
Authored By: Staff Writer | Edited: 5/10/2016
National Flag Graphic


Year: 1941
Manufacturer(s): Nakajima - Japan
Production: 819
Capabilities: Ground Attack;
Crew: 7
Length: 54.13 ft (16.5 m)
Width: 66.99 ft (20.42 m)
Height: 13.94 ft (4.25 m)
Weight (Empty): 14,396 lb (6,530 kg)
Weight (MTOW): 25,133 lb (11,400 kg)
Power: 2 x Nakajima Ha-109 radial piston engines developing 1,450 horsepower each.
Speed: 306 mph (492 kph; 266 kts)
Ceiling: 30,512 feet (9,300 m; 5.78 miles)
Range: 1,833 miles (2,950 km; 1,593 nm)
Rate-of-Climb: 1,225 ft/min (373 m/min)
Operators: Imperial Japan; Indonesia; Thailand
The Nakajima Ki-49 Donryu (meaning "storm dragon" and codenamed "Helen" by the Allies) heavy bomber was intended as a replacement for the out-classed Mitsubishi Ki-21 series of medium bomber. In reality, the newer Ki-49 design proved to be something of a disappointment to the Imperial Japanese Army Air Force as the type was a slow performer that - like most Japanese aircraft of the war - was ill-armed and under-armored. As a result, the type saw very limited production numbers (being limited to just over 800), appeared in a few variants and quickly was dismissed as a partner to the successful ki-21 instead of its direct replacement.

The Nakajima Ki-49 was drawn up by 1938 as a very utilitarian heavy bomber design. The term "heavy bomber" in this instance was carried quite loosely as the production Ki-49 could carry barely above 2,000 pounds of internal ordnance. The aircrafts design followed along the same lines of previous twin engine bomber attempts of Japanese ordnance that saw a slender fuselage with clean lines, a middle-mounted monoplane wing assembly, various gun positions adorning the design and a single vertical tail surface. Crew accommodations amounted to seven (or in some cases eight) personnel. Defensive armament (always an issue with Japanese bomber aircraft designs throughout the war) consisted of a nose-mounted 7.7mm machine gun, a 7.7mm machine gun in a tail gun position, 2 x 7.7mm machine guns in beam positions (1 gun per side), a 7.7mm machine gun in a ventral position and a 20mm cannon in a flexible dorsal mounting.

The first Ki-49 prototype went airborne in 1939 with Nakajima Ha-5 KAI radial engines of 950 horsepower each. Pre-production and the first production models would be mated with 2 x Nakajima Ha-41 radial engines of 1,250 horsepower each, increasing performance capabilities as a result. The Ki-49 would enter service in 1941 with mixed results, forcing the aircraft to undergo some much needed upgrades to armor and armament by 1942. The "improved" Ki-49 appeared in form as the Ki-49-IIa and was followed by another improved version in the Ki-49-IIb variant.

The Ki-49 was fielded extensively against China, Australia and the Burma region but the aircraft was generally outclassed by the latest crop of American and British fighters. As a result, the Ki-49 suffered heavy losses throughout the conflict and their reach was lessened by 1944. Afterwards, the Ki-49 - like most of the mid-sized Japanese aircraft of limited potential - could be seen focused on kamikaze attacks against Allied interests.


1 x 20mm Ho-1 cannon in dorsal turret (flexible mounting)
1 x 7.7mm Type 89 machine gun in nose position
1 x 7.7mm Type 89 machine gun in ventral position
1 x 7.7mm Type 89 machine gun in left beam position
1 x 7.7mm Type 89 machine gun in right beam position
1 x 7.7mm Type 89 machine gun in tail gun position

Up to 2,205 lb of internal stores.

Graphical image of an aircraft medium machine gun
Graphical image of an aircrat automatic cannon

Variants / Models

• Ki-49-I - Initial Production Model Designation
• Ki-49-IIa - "Improved" Ki-49-I Model; fitted with uprated 2 x Nakajima Ha-109 radial engines; improved armor and fuel protection; improved defensive armament.
• Ki-49-IIb - At least three of the existing 7.7mm machine guns replaced by heavy caliber 12.7mm Ho-103 types for improved defensive armament.
• Ki-49-III - Prototype Models fitted with 2,420 horsepower engines; 6 examples produced.
• Ki-58 - Experimental Escort Fighter based on the Ki-49 platform.
• Ki-80 - Experimental Escort Bomber based on the Ki-49 platform.
• Army Type 100 Heavy Bomber Model 1 - Official Designation for the Ki-49-I production model.
• Army Type 100 Heavy Bomber Model 2A - Official Designation for the Ki-49-IIa production model.
• Army Type 100 Heavy Bomber Model 2B - Official Designation for the Ki-49-IIb production model.
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