Ki-60
Specifications (Ki-60)
Data from Warplanes of the Second World War, Volume Three: Fighters; WW2 Aircraft Fact Files: Japanese Army Fighters, Part 1; Japanese Aircraft of the Pacific War.
General characteristics
Crew: One
Length: 8.40 m (27 ft 9.5 in)
Wingspan: 9.78 m (34 ft 5.5 in)
Height: 2.75 m (9 ft 10 in)
Wing area: 16.20 m² (15.9 m² first prototype) (174.376 ft² (171.15 ft²)).
Empty weight: 2,150 kg (4,740 lb)
Loaded weight: 2,750 kg (2,890 kg first prototype) (6,063 lb (6,371 lb)).
Power plant: 1 × Daimler-Benz DB 601 liquid-cooled inverted V-12, 875 kW (1,175 hp)
Performance
Maximum speed: 560 km/h (348 mph) at 4,500 meters (14,800 ft).
Service ceiling: 10,000 m (32,810 ft).
Wing loading: 169.8 kg/m² (34.8 lb/ft²).
Power/mass: 3.14 kg/kW (2.34 kg/hp; 5.16 lb/hp).
Time to altitude: 8.0 min to 5,000 meters (16,000 ft) for the 1st
prototype; 6.0 min to 5,000 meters (16,000 ft) for the 2nd and 3rd prototypes.
Armament
2 x 20 mm Mauser MG 151 cannon or 2 x 12.7 mm (0.50 in) Ho-103 machine guns in the wings.
2 x 12.7 mm (0.50 in) Ho-103 synchronized machine guns in the fuselage.
From the start of flight testing it became apparent that the design was seriously flawed in several key areas. The take-off run was unacceptably long, while in flight the aircraft displayed some lateral instability, excessively heavy controls and poor control response. The spinning characteristics were described as "dangerous" and the stalling speed was extremely high. Although a top speed of 600 kilometers per hour (370 mph) had been projected the Ki-60 was only able to achieve 548 kilometers per hour (341 mph).
As a result, the second and third prototypes, which were still being built, were hurriedly modified in an attempt to mitigate some of the more undesirable traits. Approximately 100 kilograms (220 lb) were removed, primarily by replacing the MG 151 cannon with Ho-103 machine guns. This reduced the normal loaded weight to 2,750 kilograms (6,060 lb). Coupled with a slight increase in wing area to 1.5 m2 (16 sq ft), this resulted in a slightly lower wing loading of 169.7 kg/m² (34.76 lb/ft²). Detail changes were made to airframe sealing and to the contours of the air intakes and radiator bath. Flight tests were still disappointing, with both of the modified prototypes displaying most of the shortcomings of the first. A top speed of
only 560 kilometers per hour (350 mph) was reached, with a climb rate still well below specifications. By this time the Nakajima Ki-44, which had also been designed as a dedicated interceptor, was beginning to show some promise and the Koku Hombu selected this in fulfillment of its requirements. From early 1941 the full attention of Takeo Doi and Shin Owada was focused on the Ki-61; the Ki-60 became important in that the Ki-61 design was able to be improved using the lessons learned from the poor characteristics of the Ki-60.
Plans for production were cancelled in late 1941 after three airplanes had been built.