Koshiki-2 Experimental Fighter

The Koshiki-2 Experimental Fighter was a prototype fighter aircraft designed by the Tokorozawa Aviation School of the Imperial Japanese Army. It was a single-engined, single-seat biplane and was the first single-seat fighter of wholly Japanese design and construction. Two were built and flown in 1922 and 1923 but no further production followed.

Design and development
The Provisional Military Balloon Research Association (PMBRA) (Japanese:Rinji Gunyo Seiki Kikyu Kenkyu Kai) was established at Tokorozawa, Saitama on 30 July 1909 as a joint venture by the Imperial Japanese Army and the Imperial Japanese Navy to develop both lighter-than-air and fixed wing aircraft. It soon became dominated by the Army, and developed a series of experimental aircraft as well as coordinating aviation research and aircraft procurement for the Army. The PMBRA was shut down in April 1919, with the Army Aviation School established at the same site. The aircraft research and design capability of the PMBRA was taken over by the Department of Research at the Army Aviation School.

In 1920, the Department of Research started the design of a new single-seat fighter, the Koshiki-2 (School Type 2, as it was designed at the Army Aviation School). The design was a single-engined tractor configuration biplane of wood and fabric construction of similar design to the French SPAD XIII fighter. It had single-bay wings with single I-shape interplane struts and had an all-moving horizonal tailplane. It was powered by a single 260 hp Salmson 9Z water-cooled radial engine.

The first example was completed and flown in 1922. It was the first single-seat fighter of wholly Japanese design and construction. Its performance was good, reaching a speed of 128 km/h, but, although handling was generally acceptable, the aircraft was found to have poor horizontal stability at low speeds. It was wrecked in a landing accident during the aircraft's fourth flight, when it overshot the landing ground. A second prototype was completed in 1923, but it was found to be still unstable at low speeds, and no further development or construction took place.