The Army Type 97, better known as the Nakajima Ki-27 – or “Nate” under Allied nomenclature – was the first modern fighter to serve with the Imperial Japanese Army Air Force (IJAAF). This all-metal cantilever low-wing monoplane featured classic fuselage lines, an enclosed cockpit and fixed landing gear. It proved its excellent qualities during combat service in China and along the Khalkhin-Gol river area.
At the outbreak of the Pacific war, it was the basic IJAAF fighter, seeing service in Indochina, Malaya, the Philippines, and Burma, as well as in defense of the Japanese Islands. On being superceded in first line units by more state-of-the-art successors, it continued in service until the end of the war in training units and pilot schools. Outside Japan, it served with the air forces of Manchukuo and Thailand. Origins
The first fighter aircraft competition
It is necessary to go back to the mid-twenties in order to trace the origins of the Nakajima Ki-27. In March 1927, Koku Hombu (Army Headquarters) invited bids from Mitsubishi, Nakajima, Kawasaki and Ishikawajima to design a Japanese fighter aircraft which could replace the basic fighter currently in service, the Nakajima Type Ko 4 (Ko-Shiki Yon-Gata Sentoki – in the IJAAF designation scheme, the Ko stood for Nieuport-produced aircraft, while the number 4, i.e. yon, the successive type number). The Ko 4, a license-based variety of the French Nieuport 29C1, was the first fighter to be manufactured in quantity by Japan for her IJAAF. A total of 608 machines left the Nakajima assembly line between December 1923 and January 1932. The Ko 4 was a replacement for the Type Hei 1 fighter (imported SPAD XIII) and Type Ko 3 (licensed Nieuport 24C1 and 27C1). However, the origin of the Ko 4, like the older Hei 1 and Ko 3, can be traced as far back as WW1, the French progenitor having been first flown in June 1918. There was thus an urgent requirement to replace it with a more advanced construction.
The Ishikawajima company very quickly withdrew from the project, the first such competition announced by Koku Hombu. The very early stage of the design work showed that their aircraft would not be up to the requirements specified by Koku Hombu. The remaining three competitors completed their designs and built prototypes, which subsequently underwent comparison tests.
Mitsubishi’s two prototypes of an aircraft named Hayabusa-go (Type Hayabusa, factory designation 1MF2) were built in 1928, the first one being ready in May. It was designed by a team led by Germany’s Professor Alexander Baumann and Japan’s Nobushiro Nakata, with the help of engineers Jiro Horikoshi and Jiro Tanaka. The initial assumption was for the aircraft to be a low-wing monoplane, but the Army requested a strutted high-wing monoplane with a parasol-type wing (interestingly, without a single bracing wire). The Hayabusa was of mixed construction (metal fuselage and wooden wings) with fabric covering. The power plant was the liquid-cooled twelve-cylinder V-type Mitsubishi Hispano-Suiza rated at 450 hp and delivering a maximum of 600 hp for takeoff. (450/600 hp)
Kawasaki’s construction, designated KDA-3 (Kawasaki Dockyard, Army, Model 3 – many Japanese aircraft of the ‘20s and ‘30s were designated using English abbreviations), was designed by one of the factory’s German employees, Dr Ing. Richard Vogt. It was a strutted high-wing parasol-type monoplane of metal-and-wood wing construction with fabric covering; the fuselage was all metal, modeled on the German Dornier Do H “Falke”. In March 1928 the factory built the first of three prototypes, powered by the BMW VI 6.3 engine of 450/630 hp. This machine was soon lost in a landing accident at Kagamigahara. The two following prototypes were completed in May. These were propelled by Hispano-Suiza engines of the same power rating; both plants were liquid-cooled twelve-cylinder V-type units.
May and June 1928 also saw the completion of two fighter prototypes from the Nakajima factory designated NC. This aircraft was the brainchild of a team of Japanese engineers headed by Shigejiro Ohwada and Yasushi (Yasumi?) Koyama, in cooperation with French engineers of the Dewoitine company, André Marie and Maxime Robin. This was also a strutted high-wing parasol monoplane, but of all-metal construction with fabric covering. Unlike both competitors, it was propelled by the air-cooled nine-cylinder Bristol Jupiter VI radial engine delivering 450/520 hp, later built under license by Nakajima as the Kotobuki. The NC’s construction was undoubtedly influenced by the French designers, inspired by the Nieuport Delage and Dewoitine aircraft.