The third prototype of the Ki 9, intended as a primary trainer, was flown in early 1935 but exhibited poor handling qualities because of its smaller, lighter engine and the consequent displacement of the centre of gravity. The Ki 9 was therefore abandoned as a primary trainer, and the army air force asked Tachikawa to produce, later that year, two prototypes of a new primary trainer biplane, the Ki 17.

The Tachikawa Ki-17 biplane had a slimmer fuselage, more square-cut equal-span wings and a redesigned tailplane, engine uncowled and a simplified landing gear.

The first of two prototypes was flown in July 1935 powered by a 150 hp Hitachi Ha 12 seven¬ cylinder radial engine driving a two blade propeller. Trials were successful and the only major change made to subsequent production aircraft was the deletion of the upperwing ailerons to eliminate oversensitive control inputs.

Between 1936 and 1943 Tachikawa completed 658 series Ki-17s and the type was used at four major flying schools and the Army Air Academy. The Ki-17 bore the official designation Army Type 95 III Primary Trainer, Allied codename ‘Cedar’. Some Ki 17s were later transferred to liaison or communications duties.

Ki-17
Engine: 1 x Hitachi Ha-12, 112kW
Max take-off weight: 914 kg / 2015 lb
Loaded weight: 639 kg / 1409 lb
Wingspan: 9.82 m / 32 ft 3 in
Length: 7.85 m / 26 ft 9 in
Height: 2.95 m / 10 ft 8 in
Wing area: 26.2 sq.m / 282.01 sq ft
Max. speed: 170 km/h / 106 mph
Ceiling: 5300 m / 17400 ft
Crew: 2

The Ki 9 had been designed in 1934 by Ryokichi Endo to satisfy a Japanese army air force requirement for a primary and intermediate trainer, capable in the latter case of 220 km/h (137 mph) and an endurance of 3½ hours.

First flown on January 7, 1935, the first and second prototypes were each powered by a 350 hp / 261kW Hitachi Ha 13a nine cylinder radial engine; the third aircraft, prototype for the primary trainer version, had a lower powered Nakajima NZ seven cylinder radial engine of 150 hp / 112kW.

Tests indicated centre of gravity problems for the proposed primary trainer and the Ki-9 was developed in the higher-powered intermediate training role only. As Tachikawa had suggested, the army air force found that one aircraft could not successfully carry out both duties, and accordingly the Ki 9 was ordered into production in 1935 only as the Type 95 1 Medium Grade (intermediate) Trainer.

Production deliveries began in 1935. Designated the Army Type 95-1 Medium Grade Trainer Model A and later given the Allied codename ‘Spruce’, the Tachikawa biplane had complex split-axle landing gear with fairings over the top of the wheels. In 1939 this was modified and simplified, the fuselage slightly shortened and all-up weight reduced. The resulting Army Type 95-1 Model B or Ki-9 Kai had improved manoeuvrability and flight characteristics. Both versions were used widely for blind-flying training with a folding hood over the rear cockpit, and at least one was modified with a glazed canopy over the rear cockpit for use as a staff officer transport.

Production by Tachikawa ended in 1942 after completing 2395 (in addition to the three prototypes), but in 1944 45 a further 220 were manufactured by the Tokyo Koku K.K.

It served with the army air force throughout the remainder of the 1930s and until the end of the Second World War. Some Ki 9s were used for reconnaissance or communications duties, and the type also served with the air forces of Cochin China, Manchuria and Thailand during the Pacific war. After the war, captured examples were employed for a time by the insurrectionist Indonesian forces.

The Ki-9 received the allied code name ‘Spruce’.

Ki-9 Model A
Engine: 1 x Hitachi Ha-13a, 261kW
Max take-off weight: 1580 kg / 3483 lb
Loaded weight: 1120 kg / 2469 lb
Wingspan: 10.32 m / 33 ft 10 in
Length: 7.52 m / 24 ft 8 in
Height: 3.1 m / 10 ft 2 in
Max. speed: 240 km/h / 149 mph
Ceiling: 5800 m / 19050 ft
Crew: 2