Nakajima Ki-49-I Donryu Army Bomber, type 100 model 1 (code name "Helen")
Twin-engine monoplane medium bomber with retractable landing gear and tail wheel. The development of a new medium bomber (heavy bomber, by Japanese standards) for the Japanese Army Air Force began in the spring of 1938. The new airplane was to replace the Mitsubishi Ki-21 bomber.
Based on Japan's experience in its war with China, special attention was given to providing the bomber with high speed capabilities and strong defensive weaponry so that it could operate without fighter cover. The crew needed protective armor, and self-sealing fuel tanks were essential.
The first prototype of the Ki-49 (#4901) made its first flight in August of 1939. Production of the aircraft began in August 1940, and the plane was designated as the Nakajima Ki-49-I Donryu ("Storm Dragon"), type 100 model 1.
The Ki-49-I was equipped with two air-cooled 14-cylinder radial Hakadzima Ha-41 engines rated at 1250 hp each. The plane's defensive armament included 1 Ho-1 Type 97 20mm cannon in the upper fuselage and five 7.7mm Type 89 machine guns (which were significantly modernized versions of the Vickers), located in the nose, sides, and underneath the aircraft. In addition, one gun was located in a tail turret, the first time such a turret was employed by an aircraft of the Japanese army. The bomb bay, which occupied almost the entirety of the aircraft's middle section, could carry bombs ranging from 100 to 250 kilograms, in various combinations. A normal load was 750 kilograms, an overweight load, up to 1000.
The new planes began to be delivered to the front in August of 1941 and were widely used over New Britain and New Guinea as well as in raids on the Australian port of Darwin.
It soon became evident that the Ha-41 engine's power was insufficient, and the controllability of the aircraft suffered as a result. The bomber's speed was not high enough to outrun the newer fighter planes. However, pilots approved of the plane's armor, the power of its defensive weaponry, and the reduction of that weaponry's "blind spots."
In all, 128 Ki-49-I aircraft were constructed.