The Tachikawa Aeroplane Company, established at Tachikawa in 1924, was regarded as a comparatively small organisation before the beginning of the Pacific war. However in 1937 it began the design of a two-seat army co-operation aircraft, in response to a directive by the Japanese Army Air Ministry, that was to change the company image. First flown in prototype form on 20 April 1938, the Tachikawa Ki-36 was a cantilever low-wing monoplane of all-metal basic structure, covered by a mix of light alloy and fabric. Landing gear was of fixed tailwheel type, the main units enclosed in speed fairings, and power was provided by a 450 hp (336 kW) Hitachi Ha-13 radial engine. The two-man crew was enclosed by a long 'greenhouse' canopy and both men had good fields of view, that of the observer being improved by clear-view panels in the floor. Flown in competitive trials against the Mitsubishi Ki-35, Tachikawa's design proved to be the more effective and the type was ordered into production in November 1938 as the Army Type 98 Direct Co-Operation Plane (Chokusetsu-Kyodoki), company designation Ki-36 (Kitai designation of 36). It was generally similar to the prototypes, and they were armed with one 7.7 mm (0.303 in) machine-gun offset to the starboard side firing through the cowling, which was aimed with a telescopic sight passing through the canopy and one rearward firing 7.7 mm (0.303 in) Type 89 machine gun in the observers compartment. Underwing racks could accommodate up to ten 27.5 lbs (12.47 kg) or 33 lbs (15 kg) bombs. It introduced the more powerful 510 hp (380 kW) Hitachi Ha-13a 9-cylinder radial engine. When construction ended in January 1944, a total of 1,334 had been built by Tachikawa (862) and Kawasaki (472). An advanced version of the Ki-36 was proposed under the designation Ki-72, gaining improved performance by installation of the 600 hp (447 kW) Hitachi Ha-38 engine and retractable landing gear, but no examples were built.

The handling characteristics and reliability of the Ki-36 made the army realise that it was ideal for use as an advanced trainer, resulting in development of the Ki-55, intended specifically for this role, and having armament reduced to a single forward-firing machine- gun. Following the testing of a prototype in September 1939, the army ordered this aircraft as the Army Type 99 Advanced Trainer. When production was terminated in December 1943 a total of 1,389 had been built by Tachikawa (1,078) and Kawasaki (311). In addition to the removal of the rear machine gun, the Ki-55 differed from the Ki-36 in the removal of the wheel covers (spats) from the fixed gear, the radio and antenna, bomb racks and the fuselage and underwing observation windows were covered. In order to use the Ki-55 in pilot training, a second control panel, stick and rudder assembly were installed in the rear position.

Both versions were allocated the Allied codename 'Ida', and the Ki-36 was first deployed with considerable success in China. However, when confronted by Allied fighters at the beginning of the Pacific war it was found to be too vulnerable, being re-deployed in China where it was less likely to be confronted by such aircraft. It was also considered suitable for kamikaze use in the closing stages of the war, being modified to carry internally a bomb of up to 1,102 lbs (500 kg).

(Army Type 98 Direct Co-Operation Plane - Tachikawa Ki-36)

Allied Codename: Ida

Type: Two Seat Army Co-Operation & Advanced Trainer
Accommodation/Crew: Pilot and an Observer/Gunner sitting in tandem.

Design: Tachikawa Hikoki KK Design Team

Manufacturer: Tachikawa Hikoki Kabushiki Kaisha in Tachikawa (The Tachikawa Aeroplane Company Limited) and also by Kawasaki Kokuki Kogyo Kabushiki Kaisha (The Kawasaki Aircraft Engineering Company Limited).

Powerplant: One 510 hp (380 kW) Hitachi Ha-13a 9-cylinder air-cooled radial engine.

Performance: Maximum level speed 216 mph (348 km/h) at 5,905 ft (1800 m); service ceiling 26,740 ft (8150 m).

Range: 767 miles (1235 km) on internal fuel.

Weight: Empty 2,749 lbs (1247 kg) with a maximum take-off weight of 3,660 lbs (1660 kg).

Dimensions: Span 38 ft 8 1/2 in (11.80 m); length 26 ft 3 in (11.80 m); height 11 ft 11 1/4 in (3.64 m); wing area 215.29 sq ft
(20.00 sq m).

Armament: One forward firing 7.7 mm (0.303 in) machine-gun and one 7.7 mm (0.303 in) machine-gun on a trainable mounting in the rear cockpit, plus up to 331 lbs (150 kg) of bombs.

Variants: Ki-36 (Army Co-Operation), Ki-55 (Advanced Trainer), Ki-72 (proposed).

Equipment/Avionics: Standard communications and navigation equipment.

History: First flight (prototype) 20 April 1938; end production January 1944.