Tachikawa Ki-106 (Ki-84 Hayate) All-Wood Single-Seat Fighter Prototype
The Tachikawa Ki-106 was an all-wooden form of the classic Nakajima Ki-94 Hayate fighter line.
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Because of the deteriorating war situation for Japan amidst the relentless Allied bombing campaign of the Japanese homeland, high-performance aircraft of all sorts were sought to contend with the new generation of Allied fighters and the arrival of the American Boeing B-29 "Superfortress" high-altitude heavy bomber. The Nakajima Ki-84 "Hayate" represented one of the finer mid-to-late-war fighters available to the nation and went on to see 3,514 examples produced while being regarded as the best quantitatively-available Japanese fighter of the entire conflict. It was decided to develop a low-cost, all-wood version of this fighter to reduce the reliance on valuable alloys and other precious war material needed elsewhere. This initiative became the forgotten Tachikawa "Ki-106".
The requirement appeared in September of 1943 and was assigned to Tachikawa Hikoki engineers. Their mission was to redesign the classic Ki-84 into a fully wooden form with assistance given through the Army Aerotechnical Research Institute. Beyond its all-wood construction, the aircraft was simplified for low-skilled labor to be employed in its construction process essentially making the Ki-106 a budget fighter able to be built in just about anyplace resembling a common wood shop. Final assembly would require slightly more skilled labor but the end result would be an easier-to-produce fighter platform desperately in need by the air services of Japan.
The Ki-106 mimicked much of the form and function of the all-metal Ki-84 before it. Ohjo Koku handled construction of the prototypes to which the first (of three) flew in July of 1945. The protracted development of the product meant that it did not go airborne until very late in the war when Japanese losses were insurmountable. Power came from a single Nakajima Ha-45-21 series radial piston engine driving a three-bladed propeller through 2,000 horsepower output. Wing mainplanes were featured forward of midships as in the Ki-84 and the cockpit was held over center. Armament was reduced from the 4 x 20mm cannon arrangement seen in the Ki-84 to a 2 x 20mm cannon battery as a weight-saving measure (the all-wood construction of the Ki-106 made it heavier than the all-metal form).
The three prototypes were all that was built of the Ki-106 line for the Japanese surrender of 1945 ended development of this Japanese "wooden wonder". The second prototype managed to go airborne just before the cessation of hostilities and was outfitted with its proposed armament scheme showing some progress.