Kawasaki Ki-60

While negotiating with Daimler-Benz AG for the manufacturing rights for the German DB 601A inverted-vee liquid-cooled engine, Kawasaki were successful in impressing upon members of the Koku Hombu that most contemporary foreign high-performance fighters were powered by liquid-cooled engines. Consequently, in February 1940, Kawasaki were instructed to design around the German engine, or its Japanese version, two fighter aircraft: the Ki-60 heavy interceptor and the Ki-61, a lighter all-purpose fighter. Priority was given to the Ki-60 and, in a complete reversal from previous Japanese Army requirements, speed, rate of climb and cannon armament were stressed at the expense of range and manoeuvrability.

Designed by Takeo Doi and Shin Owada, the Ki-60 was a relatively clean, all-metal stressed-skin low-wing monoplane fighter powered by one 1,100 hp Daimler-Benz DB 601A liquid-cooled engine, rated at 1,150 hp for take-off and 1,100 hp at 4,000 m (13,125 ft), and was armed with two fuselage-mounted 12.7 mm (0.5 in) Type 1 (Ho-103) machine-guns and two wing-mounted 20 mm (0.79 in) Mauser MG 151/20 cannon imported from Germany. The first prototype was completed and flown in March 1941. Although basically successful, the Ki-60 was not liked by Service test pilots who reported negatively on the aircraft's high wing loading and resultant high landing speed and noted that the aircraft reached a maximum speed of only 550 km/h (342 mph) compared to 600 km/h (373 mph) as calculated by the manufacturers. Consequently, the second Ki-60 prototype was fitted with a wing of increased area - 16.2 sq m (174.375 sq ft) against 15.9 sq m ((171.146 sq ft) - featured a redesigned and cleaner engine cowling offering reduced drag and was slightly lighter. Maximum speed increased to 560 km/h (348 mph) and manoeuvrability improved somewhat. Further improvements were obtained with the third and last prototype which, retaining the larger wing of the second prototype, had an ever smoother cowling. Weight was reduced by careful attention to detail fittings and replacement of the wing-mounted Mauser MG 151 by a pair of Ho-103 machine-guns. Despite these modifications maximum speed was still only 570 km/h (354 mph) and the Ki-60 was finally abandoned in favour of the lighter and faster Ki-61.

Technical Data
Manufacturer: Kawasaki Kokuki Kogyo KK (Kawaskai Aircraft Engineering Co Ltd).
Type: Single-engined heavy interceptor fighter.
Crew (1): Pilot in enclosed cockpit.
Powerplant: One 1,100 hp Daimler-Ben DB 601A twelve-cylinder liquid-cooled engine, driving a three-blade constant-speed metal propeller.
Armament: (first and second prototypes) Two fuselage-mounted 121.7 mm (0.5 in) Type 1 (Ho-103) machine-guns and two wing-mounted 20 mm (0.79 in) Mauser MG 151 cannon, (third prototype) two fuselage-mounted 12.7 mm (0.5 in) Type 1 (Ho-103) machine-guns and two wing-mounted 12.7 mm (0.5 in) Type 1 (Ho-103) machine-guns.
Dimensions: Span 10.5 m (34 ft 5 3/8 in); length 8.47 m (27 ft 9 15/32 in); height 3.7 m (12 ft 1 21/32 in); wing area 16.2 sq m (174.375 sq ft).
Weights: Empty 2,150 kg (4,740 lb); loaded 2,750 kg (6,063 lb); wing loading 169.8 kg/sq m (38.4 lb/sq ft); power loading 2.4 kg/hp (5.3 lb/hp).
Performance: Maximum speed 560 km/h (348 mph) at 4,500 m (14,765 ft); climb to 5,000 m (16,405 ft) in 8 min; service ceiling 10,000 m (32,810 ft).
Production: A total of three Ki-60 prototypes were built in 1941 by Kawasaki Kokuki Kogyo KK.