Mitsubishi Ki-46 (Dinah)

Mitsubishi Ki-46 (Dinah) History

From May 1937, the Empire of Japan - the air force of the Imperial Japanese Army and the air service of the Imperial Japanese Navy - relied on Mitsubishi Ki-15 aircraft for light bombing and reconnaissance missions. The aircraft has an enclosed two-person cockpit, a low-positioned monoplane wing assembly and jetted main landing gear legs, the latter of which is in a permanently fixed position. About 500 of these aircraft are in Japanese inventory, and only a few variants have been developed.

In December 1937, the Japanese Air Force made a new request for a fast, long-range reconnaissance platform to replace the outgoing Ki-15.

The Mitsubishi focus led to an entirely new design that had some basic similarities to the Ki-15, namely having a two-person crew and a low-set monoplane wing. The new plane's fuselage is rounded, with streamlined engine nacelles in each wing that drive three-bladed propellers.

The fuselage design tapers to the empennage, which is covered by a rather truncated vertical fin and applicable horizontal stabilizers. The crew will sit in two separate cockpits - the pilot in the forward compartment and the observer/tail gunner in the aft compartment forward of the stern. To meet the long-range requirements, fuel is stored in multiple locations in the design, including large storage tanks mounted between the front and rear cockpits. The Mitsubishi-branded radial piston engine is housed in a specially designed streamlined nacelle that complements the aircraft's aerodynamics. Armament is only a Type 89 self-defense machine gun set in the tail firing position to protect the aircraft's vulnerable "six".

The construction of the prototype followed and led to the designation "Ki-46".

The first recorded flight of the Ki-46 was in November 1939, proving that its engines lacked the required power output and overall speed envisioned by the IJAAF. Work on the model continued and new Mitsubishi engines were installed (Ha. 26-I radially rated at 900 hp), while the IJAAF (satisfied with the aircraft's near-term prospects) ordered the Ki-46 for serial production. The newer reconnaissance version, the Ki-46-I, was introduced in July 1941 and immediately rose to prominence in IJAAF service.

Thirty-four such examples were completed, of which 1,093 were completed, before manufacturing was converted to the final refined production form Ki-46-II.

During the Ki-46's initial combat mission, it traded through Manchukuo and China before advancing further into the Pacific. Over time, the aircraft proved to be a common sight over other regions, as the Ki-46 was a capable aircraft from the start, ideal for the advanced, fast reconnaissance missions originally intended.

Its inherent speed makes it virtually impervious to ground fire and enemy interceptor attacks. This dominance gives the IJAAF a certain sense of superiority that will be exploited as long as this dominance continues. The Ki-46 later became one of the best reconnaissance aircraft of the war.

However, the Japanese authorities did not turn a blind eye to the progress of the Allied side. The basic fighter designs have all gone through their paces and done with ever-improving performance specifications.

To stay ahead, the IJAAF commissioned Mitsubishi to improve the form of the Ki-46-II by installing a more powerful engine. Mitsubishi engineers have also improved key aerodynamics of the fuselage, including the nose, which now has a sleeker, all-glass look. The revised version first aired in December 1942 and proved to be faster than the first.

The aircraft was adopted as the Ki-46-III and 613 were delivered.

At the end of the war in 1945, in a desperate Japanese defense campaign, the Ki-46 series was converted into a heavily armed ad hoc interceptor platform. The main threat to the Japanese homeland now comes from high-altitude Boeing B-29 superfortresses, which can operate above Japanese defenses and out of range of enemy interceptors with substantial impunity.

As an interceptor bomber, the Ki-46's armament was expanded to include 2 x 20mm cannons and 1 x 37mm machine gun in oblique firing positions. The latter weapon was designed to attack bombers from behind and below - the most vulnerable areas of enemy bombers in flight.

These versions (Ki-46-III-KAI) proved adequate for role reversal, but were not as successful as expected. The airframe was simply not designed for sustained firing of large-caliber 37mm guns, especially in its semi-vertical configuration, and the aircraft struggled to reach its defined intercept altitude in time. Even if it did hit the B-29 bomber, the plane lacked any armor protection or self-sealing fuel tanks, essentially serving as target fodder against B-29 gunners.

The Ki-46-III-KAI appeared in October 1944 and entered service the following month. As U.S. aircrews switch between night operations, the tactical utility of the Ki-46 III interceptors is even less, as they were never adapted to the role of night fighters with radar or similar tracking facilities. The Ki-46-IIIb is similar to the Series III, but is designed for ground attack missions and does not use an oblique-firing 37mm gun.

There are several other experimental forms of testing the engine, but these have all failed, and others have never been implemented.

The Ki-46 was officially retired after Imperial Japan fell to the Allies in 1945. Two of these were briefly operated by the Chinese after the war, but their record of use ended in the mid-1950s.

The official name of the Ki-46 was "Type 100 Command and Reconnaissance Aircraft", and the Allied code name was "Dinah".

Specification

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Performance

Armor

Changes