Mitsubishi Ki-46

The Mitsubishi Ki-15, which entered service in 1937, confirmed very quickly the value of high-speed reconnaissance aircraft. Used operationally in the Sino-Japanese conflict, it provided the Imperial Japanese Army with invaluable intelligence of enemy concentrations and movements. Impressed by the capability of the Ki-15, and considering its requirements when the moment came for the expansion of the Japanese empire, the army drew up the specification of a higher performance long-range aircraft of this category. This would be essential considering the vast area over which operations might develop, and early and accurate knowledge of enemy countermoves would be vital if quick and effective response was to be made.

At the end of 1937 Mitsubishi received the army's specification, which made speed and range paramount to any other consideration, leaving the company free to adopt any configuration/powerplant combination that would achieve the desired performance. The resulting aircraft, first flown in prototype form in late November 1939, was a cantilever low-wing monoplane, its thin-section wings incorporating considerable dihedral. A slender fuselage mounted a conventional tail unit, landing gear was of retractable tailwheel type and power was provided by two 900-hp (671-kW) Mitsubishi Ha-26-I radial engines which were wing-mounted in very clean nacelles. In fact, considerable efforts had been made to keep drag to a minimum and the Mitsubishi Ki-46, as the type was designated, was undoubtedly one of the best-looking aircraft of World War II.

Flight testing went well, but a maximum speed some 10 per cent below that specified caused some concern. However, as the Ki-46 was faster than the most recent army and navy fighters to enter service, it was ordered into production under the official designation Army Type 100 Command Reconnaissance Plane Model 1, this version being identified by Mitsubishi as theKi-46I. Early production aircraft, which began to enter service in early 1940, were found to have a number of teething problems. While these took considerable time to rectify, at no time was production status in doubt and the development of an improved Ki-46-II was soon under way. This introduced the 1,080-hp (805-kW) Mitsubishi Ha-102 engine with two-stage supercharger, and when tested in early 1941 this new version was found just able to exceed the originally specified maximum speed of 373 mph (600 km/h). Production Ki46- IIs were delivered to operational units as quickly as production would allow, and by the beginning of the Pacific war units with small numbers of these aircraft were dispersed throughout the entire area of intended operations.

Initially the high speed of the Ki-46-IIs at their optimum altitude made them immune from interception by Allied fighters, which were then operating without the benefits of ground control radar. However, as soon as US and British forces re-established themselves and began to introduce new-generation fighters, Ki-46-II losses began to mount rapidly. Such a situation had been foreseen by the army, and by the time that it arose the Ki-46-III with more powerful Mitsubishi Ha-112-II engines was almost ready to enter service. This new reconnaissance aircraft, which supplemented rather than replaced the Ki-46-IIs, was to be virtually free from interception until the closing stages of the Pacific war. In fact, its performance was such that a fighter interceptor version was produced in small numbers under the designation Ki-46-III KAI, these being conversions from standard Ki-46-III production aircraft. They carried an armament of two nose-mounted 20mm cannon plus an obliquely-mounted 37-mm cannon in the upper fuselage, but they were not particularly successful and not many conversions were made. A small number of ground-attack aircraft was also produced by conversions of Ki-46-IIIs and these, designated Ki-46-IIIb, were armed with only nose-mounted 20-mm cannon. An improved Ki-46-IV was planned in both reconnaissance and fighter versions, but did not progress beyond the prototype stage by the war's end. Allocated the Allied codename 'Dinah', the Ki-46 was in service from the beginning to end of the Pacific war, and its significance to the Japanese army can be judged by a production total no smaller than 1,742 of all versions.
Variants
(note:- The Shiki designations must be used in full, as written below, because the Type number only refers to the year of the designs inception.)
Army Type 100 Command Reconnaissance Plane
    The Shiki designation for the Ki-46 Command Reconnaissance Plane
Army Type 100 Air Defence Fighter
    The Shiki designation for the Ki-46 Interceptor Fighter
Army Type 100 Assault Plane
    The Shiki designation for the Ki-46 Assault Plane
Ki-46
    Prototype.
Ki-46 I
    Reconnaissance version of the Ki-46.
Ki-46 II
    The first operational model of the series.
Ki-46 II KAI
    Three-seat training version of the Ki-46. Used for radio and navigation training, with a redesigned cabin, dorsal echeloned extension. Conversions of the Ki-46 II.
Ki-46 III
Ki-46 III-KAI
    Defense interceptor/night fighter version of the Ki-46. Equipped with two 20 mm cannons in the nose and one 37 mm (1.46 in) cannon in the "Schräge Musik"-style dorsal frontal position.
Ki-46 III
    Land strike version of the Ki-46, without 37 mm (1.46 in) cannon armament.
Ki-46 IIIb
    Ground-attack version.
Ki-46 IIIc
    Not built design project.
Ki-46 IV
    Prototype, equipped with two turbocharged 1,119 kW (1,500 hp) Mitsubishi Ha-112-II RU engines, and more gasoline store capacity.
Ki-46 IVa/b
    Series models of reconnaissance/fighter aircraft, Not built design projects

Specification
Mitsubishi Ki-46-III
Powerplant: two 1,500-hp (1119-kW) Mitsubishi Ha112-II 14-cylinder radial piston engines
Performance: maximum speed 391 mph (630 km/h) at 19,685 ft (6000 m); service ceiling 34,450 ft (10500 m); range 2,485 miles (4000 km)
Weights: empty 8,444 Ib (3,830 kg); maximum takeoff 14,330 lb (6500 kg)
Dimensions: span 48 ft 2 3/4 in (14.70 m); length 36 ft 1 in (11.00 m); height 12 ft 8 3/4 in (3.88 m); wing area 344.46 sq ft (32.00 m2)
Armament: none, but some Ki-46-I and Ki-46-II aircraft carried a single 7.7-mm (0.303-in) Type 89 machine-gun on a trainable mount in the rear cockpit
Operators: Japanese Army, plus a small number used by the Japanese Navy

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