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Mitsubishi Ki-18
Role prototype fighter aircraft
Manufacturer Mitsubishi Heavy Industries, Ltd
First flight August 1935
Primary user IJA Air Force
Number built 1

The Mitsubishi Ki-18 (三菱 キ18 Ki-jyuhachi?) was an unsuccessful and unsolicited attempt by Mitsubishi to meet a 1934 requirement issued by the Japanese Army for a modern single-seat monoplane fighter suitable to the needs of the Imperial Japanese Army Air Force. During this competition, Nakajima entered the Nakajima Ki-11 (which was somewhat similar to the Boeing P-26 Peashooter), and Kawasaki entered the more maneuverable Kawasaki Ki-10 biplane. The competition was won by Kawasaki, but the new fighter was not accepted by the IJAAF with much enthusiasm.[1]

Design and development

In 1934, Mitsubishi had developed the Ka-14 9-Shi fighter prototype specifically for an Imperial Japanese Navy requirement. The design exhibited outstanding performance, and with the Navy's consent, the Army placed a contract with Mitsubishi for a modified version for evaluation, which was designated the Ki-18.[1][2]

The Ki-18 was a low-wing monoplane of all-metal construction with fabric-covered control surfaces. It was powered by a Nakajima Kotobuki-5 nine-cylinder radial engines, rated at 410 kW (550 hp) for take-off, and 447 kW (600 hp) at 3,100 m (10,170 ft), driving a two-blade fixed-pitch wooden propeller.

The main external differences between the Ki-18 and the Ka-14 included an enlarged rudder, larger landing gear (with spats) and an engine cowling. Internally, the direction of the throttle movement was reversed to meet Army practice, and the machine guns were replaced with Army standard weaponry.

The Ki-18 made its first flight on completed in August 1935 at the Army's Tachikawa Air Technical Research Institute, and was later tested at the Akeno Army Flying School through the end of 1935.[1] In early 1936, the engine was changed to the Nakajima Kotobuki 3, rated at 477 kW (640 hp) for take-off and 533 kW (715 hp) at 2,800 m (9,190 ft). During testing, the Ki-18 achieved a maximum speed of 444 km/h (276 mph) at 3,050 m (10,010 ft) was recorded, and the aircraft was able to climb to 5,000 m (16,400 ft) in 6 minutes 25.8 seconds, which was considered an exceptional rate for the time.[1] The Akeno Army Flying School test results gave the Ki-18 a very high recommendation, and it was proposed that the fighter be produced for front-line service. However, the Army Air Technical Research Institute was vehemently against using a Navy design, and after choosing to ignore the data, claimed that the Nakajima Kotobuki engines were "unreliable" and that the Ki-18 lacked the performance necessary for an Army fighter. Instead, the Army Air Technical Research Institute recommended that a new competition would be staged, with Nakajima, Kawasaki and Mitsubishi invited to participate. As the Ki-10 had entered production only one year earlier, this proposal was immediately vetoed by the Imperial Japanese Army General Staff. Thus, the Ki-18 ended with only one aircraft, although the essentially identical Ka-14 was accepted as a revolutionary fighter by the Japanese Navy as the Mitsubishi A5M Type 96 carrier-based fighter.[1]


  • Ki-18 : Prototype for testing (1 unit produced)



Specifications (Ki-18)

Data from Japanese Aircraft, 1910-1941;[1] Famous Airplanes of the World, first series, #76: Army Experimental Fighters (1)[3]

General characteristics

  • Crew: 1
  • Length: 7.655 m (25 ft 1¼ in)
  • Wingspan: 11.0 m (36 ft 1 in)
  • Height: 3.15 m (10 ft 4 in)
  • Wing area: 17.8 m² (191.603 ft²)
  • Empty weight: 1,110 kg (2,447 lb)
  • Loaded weight: 1,422 kg (3,135 lb)
  • Powerplant: 1 × Nakajima Kotobuki-5 9-cylinder piston radial engine, 447 kW (600 hp)


  • Maximum speed: 444 km/h at 3,050 m (276 mph at 10,171 ft)
  • Range: 420 km (260 mi)
  • Rate of climb: 12.95 m/s (2550 ft/min)
  • Wing loading: 79.9 kg/m² (16.3 lb/ft²)
  • Power/mass: 0.31 kW/kg (0.19 hp/lb; 0.42 hp/kg)


2× fixed forward-firing 7.7 mm (.303 in) Type 89 machine guns

See also


  1. 1.0 1.1 1.2 1.3 1.4 1.5 Mikesh and Abe 1990, p. 187.
  2. Januszewski 2003, pp. 10–11.
  3. FAOW 1976, p. 2.
  • Francillon, Ph.D., René J. Japanese Aircraft of the Pacific War. London: Putnam & Company Ltd., 1970 (second edition 1979). ISBN 0-370-30251-6.
  • Januszewski, Tadeusz. Mitsubishi A5M Claude. Sandomierz, Poland/Redbourn, UK: Mushroom Model Publications, 2003. ISBN 83-917178-0-1.
  • Mikesh, Robert C. and Shorzoe Abe. Japanese Aircraft, 1910-1941. Annapolis, MD: Naval Institute Press, 1990. ISBN 1-55750-563-2.
  • Unknown author. Famous Airplanes of the World, first series, #76: Army Experimental Fighters (1). Tokyo: Bunrin-Do, August 1976.
  • Unknown author. Famous Airplanes of the World, second series, #24: Army Experimental Fighters. Tokyo: Bunrin-Do, September 1990.

External links

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