Before the start of World War 2 (1939-1945), there were authorities within the German Luftwaffe that championed the need for a dedicated four-engined, long-range strategic heavy bomber. However, nothing became of the "Ural Bomber" program by the time of the fighting, its greatest proponent - Generalleutnant Walther Wever passing away in June of 1936. The Junkers Ju 89 was the product of the initiative though only two were ever completed, the first prototype flying in April of 1937 and the Ju 89 project cancelled in full in April 1937. A third prototype was reworked as a long-range commercial market transport as the "Ju 90" (Ju 89 V3) and both the V2 and V3 forms served the Luftwaffe in the Norway Campaign as heavy haulers until 1940.
The Ju 90 transport-minded series itself spawned eighteen operational-level examples before the end and this design laid the groundwork for development of the "Ju 290" as well (sixty-five built for transport and maritime patrol roles with series introduction in August 1942). Back in 1938, Japanese authorities took an interest in the Ju 90 design for its fighting forces (namely the Imperial Japanese Army - IJA), too, lacked a long-range strategic heavy bomber to pound far-off enemy targets. This led to talks between German-based Junkers and Japan's own Mitsubishi to develop a local version as the "Ki-90".
By this time, Germany had become Japan's greatest ally in the world and a technology exchange emerged in which Japan had access to many German aircraft developments - typically designs rejected by the Luftwaffe with later forms centered around turbojet and rocket technologies. This arrangement proved more beneficial to the Japanese whose aero-industry fell behind its competitors on the world stage and existing designs could be used to level the playing field for the island nation against potential enemies in the United States and across the British Empire.
Despite ongoing talks between the two parties into the latter parts of the 1930s, the Ju 90 bomber concept all but fizzled out as Germany became fully embroiled in its World War across Europe and Africa - committing all of its resources to the war effort. This left Japan with its heavy bomber requirement unfulfilled. It then approached the Focke-Wulf concern of Germany in an attempt to convert its Fw 200 "Condor" four-engined aircraft into a capable strategic-level bombing platform. This endeavor, too, failed as IJA authorities remained unconvinced of the Fw 200's potential in the role. The Imperial Japanese Navy (IJN), however, did press ahead with an Fw 200 bomber form but the outbreak of war heavily restricted exportation from Germany - which ultimately killed this initiative as well.
As designed from the Ju 90, the Ki-90 heavy bomber proposal for the IJA would have retained much of the form-and-function of the original: the fuselage was to be of a unique square shape (when viewed from the forward profile) with rounded edges for streamlining. The mainplanes were low-mounted under the fuselage and positioned ahead of midships with each wing housing a pair of air-cooled radial piston engines - the inner-most nacelles home to the single-wheeled main landing gear legs from the "tail dragger" undercarriage configuration. The flight deck was to be of stepped configuration with the nose glazed over for the bombardier and navigator positions. The tail unit was to incorporate a twin vertical plane arrangement with individual horizontal planes attaching to the sides of the tapering empennage.
In terms of defensive armament, Ki-91 would have been equipped with the usual mix of IJA weaponry to help defend the various quadrants about the aircraft from intercepting enemy fighters. There would be a gun position at the nose and a possible emplacement at the tail with a turret featured along the dorsal fuselage spine line (aft of midships). Completing the defensive network were staggered side (waist/beam) positions. Offensively, the bombload was unknown but the entire collection of drop ordnance would have been held internally.
Based on the structure of the Ju 90A-1, the Ki-90 was to have a wingspan of 114.1 feet, a length of 86.4 feet, and a height of 24.7 feet. Empty weight reached 43,500lb against an MTOW of 74,300lb. Performance included a maximum speed of 217 miles-per-hour with a range out to 775 miles and an operational service ceiling just under 20,000 feet. At least eight crewmen would be featured (two pilots, bombardier, navigator, tail gunner, fuselage gunners).
Power would have been derived from the IJA equivalent of the German BMW 132 air-cooled radial piston engines driving three-bladed propeller units.
At any rate, the Ki-90 was stillborn and for the duration of World War 2, the IJA and IJN fought without a true heavy bomber component - instead relying on a broad mix of medium-types and limited attacker platforms. Conversely, its greatest enemy of the Pacific Theater - the United States - fielded excellent bombers in the Consolidated B-24 and Boeing B-17, ultimately leading up to the war-winning Boeing B-29 Superfortress.
(OPERATORS list includes past, present, and future operators when applicable)
✓Ground Attack (Bombing, Strafing)
Ability to conduct aerial bombing of ground targets by way of (but not limited to) guns, bombs, missiles, rockets, and the like.
General transport functionality to move supplies/cargo or personnel (including wounded and VIP) over range.
Used in the Very-Important-Person (VIP) passenger transport role, typically with above-average amenities and luxuries as standard.
✓X-Plane (Developmental, Prototype, Technology Demonstrator)
Aircraft developed for the role of prototyping, technology demonstration, or research / data collection.
86.9 ft (26.50 m)
114.8 ft (35.00 m)
24.6 ft (7.50 m)
42,384 lb (19,225 kg)
74,296 lb (33,700 kg)
+31,912 lb (+14,475 kg)
(Showcased structural values pertain to the base Mitsubishi Ki-90 production variant)
ESTIMATED: 4 x Mitsubishi Ha-2-II air-cooled radial piston engines of 800-820 horsepower output driving three-bladed propeller units.
ASSUMED (Based on the Junkers Ju 90 V8 arrangement):
1 x 20mm automatic cannon in nose.
1 x 20mm automatic cannon in dorsal turret emplacement.
1 x 13mm machine gun in left waist (beam) position.
1 x 13mm machine gun in right waist (beam) position.
1 x 13mm Machine gun in tail station.
Conventional drop bomb load held internally.
(Not all ordnance types may be represented in the showcase above)
Hardpoint Mountings: 0
Ki-90 - Base Project Designation; project cancelled prior to the beginning of World War 2 in September of 1939.
Ribbon graphics not necessarily indicative of actual historical campaign ribbons. Ribbons are clickable to their respective aerial campaigns / operations / aviation periods.
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