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Kawasaki Ki-60

1941 WORLD WAR 2 X-PLANE

History of the Kawasaki Ki-60

The Kawasaki Ki-60 was a completely abandoned interceptor/fighter design back in 1941, the program was born in 1939 at the request of the Imperial Japanese Army (IJA). Cooled in-line piston engines and improved aerodynamics to promote a strong rate of climb, while using the cannon as the primary weapon to compete with the latest Allied offerings - especially larger, heavier bomber types.

The engine of choice is a German Daimler-Benz DB 601 inline engine, locally built in Japan as a Kawasaki "Ha-40", expected to deliver 1,175 horsepower. Kawasaki was also responsible for the design and development of the airframe, a work credited to engineers Takeo Doi and Shin Owada.

Doi eventually worked on several notable Japanese aircraft designs, including the Ki-45 "Toryu" heavy fighter and the Ki-100 fighter.

The Ki-60 will be part of a two-phase program, with the Ki-60 representing the heavier machine gun armed interceptor and the Ki-61 "Hien" the light machine gun armed fighter. Work on the Ki-60 began in February 1940 and was completed in airworthy form in March 1941.

By this point, the Empire of Japan, along with their Commonwealth allies, was fully involved in World War II (mainly Britain) against the major factions of the Pacific Rim (the United States did not officially declare war on Japan until December 1941).

The Ki-60 was originally intended to carry 2 x .50 caliber Ho-103 heavy machine guns in the nose and 2 x 20mm Mauser MG 151 cannons in the wings, which would give it great firepower against any modern aircraft type of the period . The bow guns were fired synchronously by rotating propeller blades and mounted slightly offset from each other - the gun on the left protruded slightly more than the one on the right. Mauser guns are mounted on the wings, one per wing. While slower firing rates and limited ammunition supplies compared to machine guns, cannons are great for taking down larger bombers whose frames are bent to absorb most of the penalty of a machine gun weapon. A single shell can hit one engine directly and wreak havoc, putting the entire bomber at risk.

As an interceptor, the Ki-60 does not need to provide external munitions such as bombs, and there is no mention of airborne missiles.

The external configuration of the Ki-60 is basically conventional, with the engine in the front compartment, the cockpit in the middle, and the tapered tail. An inline engine drives a three-blade propeller assembly synchronized with two machine guns. The cockpit is located amidships with ample visibility to the nose and sides. The tail of the canopy has a raised spine, although the tail section is finished transparent to improve the "six"'s visibility.

The raised spine projects a deep fuselage for the aircraft, as does the radiator mounting between the main units of the wings. Each main wing unit is of a straight design with a rounded tip and is fitted with a cannon or machine gun installation and supplied with appropriate ammunition.

The tail has a vertical tail (circular) and low level. The landing gear consists of a pair of retractable main legs (with one wheel) and a tail wheel.

This makes the plane appear "nose-up" when stationary, which, combined with poor cockpit visibility, makes it difficult for pilots to walk and taxi on the ground.

The Ki-60 prototype tested lower than expected at the time of its manufacture, proving that it was too heavy and too slow to be controlled, and exhibited some dangerous flight characteristics when launched. She recorded a top speed of just 350 mph. Subsequent prototypes were modified at Kawasaki still under construction. To save weight, the Mauser cannons were dropped and replaced with lighter Ho-103 heavy machine guns - reducing the interceptor's overall combat effectiveness to just four machine guns. Wing area was increased for better stability, and general aerodynamic improvements were made to the fuselage.

The second and third prototypes were eventually completed to this new standard, but only increased top speed by 10 mph, and their rate of climb was pedestrian for an interceptor type - they reached it in 6 minutes 16,000 feet. The operating limit listed is usefully 32,800 feet.

With the involvement of Imperial Japan now spreading to Asia and the wider Pacific, problematic projects like the Ki-60 were abandoned - only three prototypes have ever been completed. The Ki-61 "Hien" fighter was improved (with some lessons learned from the development of the Ki-60) and was able to build 3,159 prototypes for the IJAAF, the first of which entered service in 1943.

This model is also the origin of the Qi-100 fighter, of which the 395 appeared in early 1945. The IJAAF replaced the original Ki-60 specification with Nakajima Ki-44 "Shoki" fighter jets, which were introduced in 1942 and produced 1,225 by the end of the war in September 1945.