Rikugun Ki-93 Heavy Fighter / Anti-Shipping Attack Aircraft Prototype
Intended for the Imperial Japanese Army of World War 2, the Rikugun Ki-93 heavy fighter only saw one completed prototype before the end, a second laying unfinished.
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The heavy fighter as a military aircraft class was a constant throughout the inventories of the air services participating in World War 2. Japanese seemed to take a particular interest in the type and held a stable of several strong performers during the period while other designs either failed outright or were ultimately abandoned as the war progressed. The Rikugun Ki-93 was another entry into the category but this design only ever reached the prototype stage with one example completed and a second left unfinished by war's end.
The Ki-93 began life through an initiative by the Japanese Army Aerotechnical Research Institute in 1941. Design studies were undertaken to produce an advanced twin engine, all-metal heavy-class fighter to be powered by a pair of Mitsubishi radials and work spanned into 1943 before a contract was formally issued in February covering two prototypes and one test article.
The finalized design came to be of a conventional heavy fighter arrangement: a slim fuselage would feature a crew of two in tandem (back-to-back) sitting under a heavily-glazed canopy, engines mounted under low-set monoplane wing assemblies, and a "tail dragger" undercarriage used. The tail unit was traditional with its single fin and low-mounted stabilizers. Both the cockpit and wing mainplanes were affixed ahead of midships. Overall dimensions included a length of 46.7 feet, a wingspan of 62.3 feet and a height of 16 feet. Empty weight was 17,000 lb against a gross weight of 25,220 lb.
Power was to come from 2 x Mitsubishi Ha-211 18-cylinder twin-row radial piston engines each delivering 1,970 horsepower on take-off and driving six-bladed propellers. These were fitted to underslung nacelles protruding from the wing leading edges. Performance specifications indicated a sound aircraft for the period with a maximum speed of 388 miles per hour, a cruising speed of 215 miles per hour, a range out to 1,865 miles and a service ceiling of 39,535 feet. Performance was only a key concern for the low-to-medium flight envelopes expected of the machine for its attack role. For this reason, the cockpit section was also armored.
Intended armament for the type was a single 57mm Ho-402 cannon set within a ventral gondola and 2 x 20mm Ho-5 cannons fitted to the wing roots. For defense against trailing interceptors, the rear crewman managed a 12.7mm Ho-103 heavy machine gun on a trainable mount.
Beyond the basic "Ki-93-Ia" heavy fighter / bomber destroyer version planned, there was also a proposed anti-shipping variant as the "Ki-93-Ib" It would carry a 75mm cannon (in the ventral gondola) as well as support 2 x 550lb conventional drop bombs. It is conceivable that both forms would ultimately support launch rails for rockets given their dedicated attack roles.
Completed in March of 1945, first flight of the initial Ki-93 prototype was finally had on April 8th. By this time it was obvious that the Ki-93 had been in development for far too long considering the worsening war situation for Japan - the war had now turned into a defensive one in nature. The twenty minute test flight over Tachikawa Airfield involving two crewmembers ended with a crash as the aircraft hit ahead of the runway, damaging the portside undercarriage, engine and propeller. While the crew escaped, the damage was such that it delayed the program some four weeks as repairs were undertaken. To add further woe to its development phase, an Allied air raid destroyed the Ki-93's hangar - helping to end the project prematurely. The second prototype under construction was never made ready before the end of the war as equipment was still being fitted.