Extensively test-flown in 1934, the Nakajima Ki-4 sesquiplane had divided landing gear with streamlined wheel spats, and accommodated pilot and observer in tandem open cockpits, the pilot just below a cut-out in the trailing edge of the upper wing. With twin forward-firing 7.7-mm (0.303-in) Type 89 machine-guns in front of the pilot and single or twin guns on a ring mounting in the rear cockpit. With fewer guns, it could carry a 50-kg (110-lb) bombload and be used for ground attack or dive-bombing. The powerplant was a single 600-hp Nakajinia Ha-8 Hikari radial engine, fitted with an exhaust collector ring and driving a two-blade propeller. Landing gear was normally of the twin mainwheel type, with a tail skid.
The Ki-4 went into production and service in 1935 to replace the earlier Kawasaki KDA-2 (Type 88), as the Army Type 94 Reconnaissance Aircraft Model 2 which dispensed with the wheel fairings and had a redesigned tail unit.
The Type 94 was used widely in China by the Japanese army on direct co-operation duties, in close support of the ground forces. The Japanese army tested two Ki-4s as seaplanes, one with twin floats and the other with one main and two stabilising floats. A landplane was used for flotation bag tests to check buoyancy in the event of an emergency put-down on water.
A total of 516 were built, some aircraft being licence-built by Tachikawa.
Ki-4 Type 94
Engine: 1 x Ha-8, 477kW
Span upper: 12 m (39 ft 4 in)
Span lower: 8.52 m (27 ft 11 in)
Length: 7.73 m (25 ft 4 in)
Gross weight: 2616 kg (5767 lb)
Maximum speed: 300 km/h (186 mph).
Armament: 4 x 7.7mm machine-guns, 50kg of bombs