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Ki-49 "Helen", Japanese Heavy Bomber


Photograph of Ki-49 "Helen"

U.S. National Archives. Via Francillon (1979)

3-view diagram of Ki-49 "Helen"

U.S. Army Via ibiblio.org


Nakajima Ki-49-IIa Donryu ("Storm Dragon") "Helen"


Specifications:


Crew 8
Dimensions       67'0" by 54'2" by 14'0"
20.42m by 16.51m by 4.27m
Wing area 743 square feet
69 square meters
Weight 14,396-25,133 lbs
6530-11,400 kg
Maximum speed        306 mph at 16,405 feet
492 km/h at 5000 meters
Cruise speed 217 mph at 9845 feet
349 km/h at 3000 meters
Climb rate 20 feet per second
6.1 meters per second
Service ceiling
30,510 feet
9300 m
Power plant
Two 1450 hp (1081 kW) Nakajima Ha-109-II 14-cylinder two-row radial engines driving constant-speed three-blade metal propellers
Armament 1 20mm cannon in dorsal position
5 7.7mm Type 89 machine guns in nose, ventral, two beam, and tail positions.
Bomb load Normal 1653 lbs (750 kg)
Maximum 2205 lbs (1000 kg)
Kamikaze 3527 lbs (1600 kg)
Range 1243 miles (2000 km) normal
1833 miles (2950 km) maximum
Production A total of 819 Ki-49s as follows:


Nakajima Hikoki K.K. at Ota:



10 Ki-49 pre-production (1939 to 1940-12)



129 Ki-49-I (1941-8 to 1942-8)



2 Ki-49-II prototypes (1942-8 to 1942-9)



617 Ki-49-II (1942-9 to 1944-12)



11 Ki-49-II, Ki-58, and Ki-80 prototypes (1940-12 to 1943-12)
Variants

The Ki-49-I used two 1250 hp (932 kW) Nakajima Ha-41 engines and had only two 7.7mm machine guns, in nose and tail.

The Ki-49-IIb replaced the 7.7mm machine guns in the ventral and two beam positions with 12.7mm machine guns.


Designed to replace the Sally, the Helen was was not very successful, being difficult to handle while offering little improvement in performance or bomb load over its predecessor. It did have good defensive armament, armor, and self-sealing fuel tanks, reflecting a requirement that it be able to operate without fighter escort, though it was no more successful at this than Allied heavy bombers over Germany. It was also the first Japanese Army bomber to be fitted with a tail turret.

The aircraft was designed by a team led by T. Koyama that began its work in the summer of 1938. The team worked from detailed plans for the Sally and the prototype made its first flights in August 1939. The production model made its combat debut in China but was first encountered by the Western Allies on 19 February 1942 over Darwin. Japanese pilots found it underpowered even after the original Ha-41 engines were replaced with more powerful Ha-109 engines, and it never fully replaced the Sally. An attempt to upgrade to 2420 hp (1804 kW) Ha-117 engines was not a success due to teething troubles with the experimental engines.

The armor and armament were praised by its crews, who commented on the lack of blind spots for the gunners everywhere but directly above or below the aircraft.However, the Helen squadrons were badly mauled in the second Philippines campaign. Most were converted to transports or suicide planes or were fitted with antisubmarine radar or magnetic mine detectors for ocean patrol by 1945. An experimental escort version carrying heavy cannon armament, the Ki-58, was abandoned when the Ki-43 Oscar proved to have enough range to make an acceptable escort fighter.

References

Francillon (1979)

Wilson (1998)



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