In the early 1930s, the Imperial Japanese Army Air Force (IJAAF) relied on two primary fighter types: the Nakajima NC (Army Type 91) monoplane and the Kawasaki KDA-5 (Army Type 92) biplane.
Though serviceable, both were significantly slower than contemporary Western fighters such as the Hawker Fury of the RAF and the Boeing P-26A entering service with the USAAC.
Seeking parity with foreign designs, Kawasaki developed the Ki-5 in 1933—a sleek, inverted gull-wing monoplane.
However, its poor manoeuvrability led to its rejection in 1934.
Following the Ki-5’s failure, the Koku Hombu (Army Aviation Headquarters) issued parallel contracts:
Kawasaki was tasked with designing a high-performance biplane, while Nakajima pursued a monoplane alternative.
This led to the birth of the Kawasaki Ki-10, a conservative but refined biplane designed by Takeo Doi, assisted by engineers Imachi and Tojo.
Design Features
The Ki-10 was a single-seat, open-cockpit biplane with an all-metal structure and fabric-covered surfaces.
It featured unequal-span wings with ailerons only on the upper wing and was powered by an 850 hp Kawasaki Ha-9-IIa liquid-cooled V12 engine driving a two-blade fixed-pitch propeller.
The first prototype flew in March 1935, followed by a second in April.
Flight tests confirmed superior speed and agility compared to the Ki-5.
Despite its strengths, the competing Nakajima Ki-11 monoplane was faster.
To close the performance gap, Kawasaki modified the third prototype with a three-blade metal propeller and flush rivets.
The fourth prototype added increased dihedral to the upper wing for improved stability.
Though still slower than the Ki-11, the Ki-10’s exceptional manoeuvrability won it the production contract.
Variant Evolution
Ki-10-I
(Army Type 95 Fighter Model 1)
Production
300 units (Dec 1935 – Oct 1937)
Based on the third prototype, this initial production model served as the IJAAF’s frontline fighter during the early stages of the Second Sino-Japanese War.
Ki-10-II (Army Type 95 Fighter Model 2)
Prototype
1 unit (May 1936)
Production
280 units (June 1937 – Dec 1938)
Featured a lengthened fuselage and larger wingspan for improved stability.
This version replaced the Ki-10-I in frontline service.
Ki-10-I KAI
Prototype
1 unit (Oct 1936)
A refined version with aerodynamic improvements:
Relocated radiator between redesigned cantilever landing gear
Streamlined cowling
Achieved a top speed of 261 mph (420 km/h)—about 20 km/h faster than the Ki-10-I
Ki-10-II KAI
Prototypes
2 units (Nov 1937)
Combined the Ki-10-I KAI’s aerodynamic refinements with the Ki-10-II airframe
Powered by the Ha-9-IIb engine (950 hp at 3,800 m) and fitted with a three-blade metal propeller
Reached a top speed of 276.5 mph (445 km/h)—nearly matching the monoplane Nakajima Ki-27
Despite its performance, it remained a prototype, as biplane fighters were becoming obsolete
Operational Service
The Ki-10 series served with IJAAF units in Japan, Formosa (Taiwan), Korea, and Manchukuo and saw combat in China and Manchuria during the Second Sino-Japanese War and the Nomonhan Incident against Soviet forces.
By the outbreak of the Pacific War, the Ki-10 had been relegated to training, reconnaissance, and secondary duties.
Allied intelligence initially believed it was still in frontline service and assigned it the reporting name Perry, though sightings were rare.
