The Ki-15 was designed by the Mitsubishi corporation to meet an Imperial Japanese Army Air Force requirement of 1935 for a two-seat, high-speed reconnaissance aircraft. The resulting aircraft was a low-wing cantilever monoplane with a fixed, spatted undercarriage, similar to other all-metal stressed-skin monoplanes developed elsewhere in 1930s, such as the Heinkel He 70 and the Northrop Alpha. Power was by a single Nakajima Ha-8 radial engine, giving 560 kW (750 hp) at 4,000 m (13,120 ft). The first prototype flew in May 1936, with testing proving successful, the aircraft meeting all performance requirements, reaching a speed of 481 km/h (299 mph) and showing good handling characteristics.
Service testing was completed without difficulty and the type was ordered into production under the official designation Army Type 97 Command Reconnaissance Plane Model 1 In May 1937, a year after the first flight, delivery of the first of 437 production aircraft to the army began.
World record flight to Europe and other civilian use
Despite the relatively weak engine and fixed undercarriage, the Ki-15 was remarkably fast. During the initial flight testing, the Asahi newspaper Asahi Shimbun obtained permission to purchase the second prototype. The aircraft was given the designation Karigane (Wild Goose), flying on 19 March 1937, being named Kamikaze and registered as J-BAAI. It was the first Japanese-built airplane to fly to Europe and caused a sensation in 1937 by making the flight between Tokyo and London, for the coronation of King George VI and Queen Elizabeth, between 6 April 1937 and 9 April 1937 in a flight time of 51 hours, 17 minutes and 23 seconds, a world record at the time Following the success of the Japan-England flight, a small number of Ki-15s were sold to civil customers. One of the early production aircraft was named "Asakaze" (J-BAAL) and was also used by the Asahi Shimbun newspaper; others were used by various civilian operators as mail planes.
- Karigane I : Prototype version for civilian use
- Ki-15-I (Army Type 97 Command Reconnaissance Plane Model 1) : Initial production variant for the Japanese Army, with Nakajima Ha-8 (Army Type 94) 640 hp at take-off, 900 hp at 11,810 ft (3,600 m)
- Ki-15-II (Army Type 97 Command Reconnaissance Plane Model 2) : Improved Army production version with smaller, more powerful engine 14-cylinder Mitsubishi Ha-25-I (Army Type 99 Model 1), with 850 hp at take-off, 900 hp at 11,810 ft. This gave an increased maximum speed of 317 mph at 14,205 ft (510 km/h at 4,300 m), roughly comparabile with fighters like Hawker Hurricane or the Nakajima Ki-43 Hayabusa. The climb was even more improved: 16,405 ft (5,000 m) in 6 min 49 sec (6,83 min). This was achieved despite the increase in weight (empty, normal, max: 3,510 vs 3,084 lb, normal 4,826 vs 4,482 and max 5,470 vs 5,071 lb). Maiden flight in June 1938, production started in September 1939
- Ki-15-III : Proposed upgraded version, did not enter production version. It had the Mitsubishi Ha-102 engine (1,080 hp at take-off, 1,055 hp at 9,185 ft and 950 hp at 19,030 ft), with a top speed of 329 mph (530 km/h), roughly the same of Ki-46 Dinah. But this latter was expected to be far better in other ways (endurance, two engine, etc.), so this version never went in production, even if it was proposed since 1939
- C5M1 (Navy Type 98 Reconnaissance Plane Model I) : Improved version of Ki-15-I for the Japanese Navy
- C5M2 (Navy Type 98 Reconnaissance Plane Model 2) : Upgraded version of C5M1 with more powerful engine for the Japanese Navy