The Tachikawa KKY, full name Tachikawa Army Small and Light Ambulance Aircraft, was designed to rescue injured or sick patients from places without established airfields. Following two earlier prototypes, twenty-one production examples were built between 1936 and 1940 and served in the

Second Sino-Japanese War The Second Sino-Japanese War was fought between the Republic of China (1912–1949), Republic of China and the Empire of Japan between 1937 and 1945, following a period of war localized to Manchuria that started in 1931. It is considered part ...

Design and development

In August 1932, the Japanese Army placed an order for a small ambulance aircraft, capable of using rough airstrips and holding two stretcher cases and a medical attendant, with what was then the Aeroplane Factory of Ishikawajima Shipbuilding Company. Though the prototype was completed in December 1933, its development was protracted, and it was not ready for production until 1936. By then, the Ishikawajima Company had become the Tachikawa Aeroplane Co. It was a single bay cabin biplane with wings attached to the upper and lower

longerons In engineering, a longeron or stringer is a load-bearing component of a framework. The term is commonly used in connection with aircraft fuselages and automobile chassis. Longerons are used in conjunction with stringers to form structural frame ...

and braced on each side with near-parallel

interplane strut In aeronautics, bracing comprises additional structural members which stiffen the functional airframe to give it rigidity and strength under load. Bracing may be applied both internally and externally, and may take the form of struts, which act in ...

s. The wings had wooden structures and were fabric-covered. The KKY was powered by a

Cirrus Hermes The Cirrus and Hermes or Cirrus-Hermes are a series of British aero engines manufactured, under various changes of ownership, from the 1920s until the 1950s. The engines were all air-cooled, four-cylinder inline types, with earlier ones upright a ...

IV four cylinder air-cooled, inverted inline engine and the later KKY-2 by a

Gasuden Jimpu The Gasuden Jimpu or Kamikaze (later produced by Hitachi) was a Japanese seven-cylinder air-cooled radial Radial is a geometric term of location which may refer to: Mathematics and Direction * Vector (geometric), a line * Radius, adjective for ...

seven cylinder

radial engine The radial engine is a reciprocating engine, reciprocating type internal combustion engine, internal combustion engine configuration in which the cylinder (engine), cylinders "radiate" outward from a central crankcase like the spokes of a wheel. ...

. The fuselage had a welded steel tube structure, flat-sided behind the engine, with a windowed cabin that included the pilot's seat just ahead of the wing

leading edge The leading edge is the part of the wing that first contacts the air;Crane, Dale: ''Dictionary of Aeronautical Terms, third edition'', page 305. Aviation Supplies & Academics, 1997. alternatively it is the foremost edge of an airfoil sectio ...

with the patients and attendant under the wing. The tail, with an aluminium structure and fabric-covered, was conventional with a

tailplane A tailplane, also known as a horizontal stabilizer, is a small lift (force), lifting surface located on the tail (empennage) behind the main lifting surfaces of a fixed-wing aircraft as well as other non-fixed-wing aircraft such as helicopters ...

on top of the fuselage and braced to it from below. The vertical tail had a strongly-blunted triangular profile. As its purpose was to rescue patients from rough airfields or unmade airstrips, the ambulance needed a robust

undercarriage Undercarriage is the part of a moving vehicle that is underneath the main body of the vehicle. The term originally applied to this part of a horse-drawn carriage, and usage has since broadened to include: *The landing gear of an aircraft. *The ch ...

. This had split axles mounted on a short, central, V-strut from the fuselage underside. Both short, faired shock absorber legs and their rearward drag struts were mounted on the lower fuselage

. Wheels with wide, low-pressure tires were available for missions to unmade strips.

Operational history

Twenty-one ''Aikoku-go'' (privately funded) production KKYs were built between 1936 and 1940. They were active in the Second Sino-Japanese War, which began in 1937 and became part of World War II, when China entered on the Allies' side shortly after the attack on

Pearl Harbor Pearl Harbor is an American lagoon harbor on the island of Oahu, Hawaii, west of Honolulu. It was often visited by the naval fleet of the United States, before it was acquired from the Hawaiian Kingdom by the U.S. with the signing of the Reci ...

Variants

;KKY: As described. Two prototypes plus production aircraft from 1936 to October 1938. ;KKY-2: The production aircraft from October 1938, powered by a

seven cylinder

driving a wooden propeller. It had increased area wings with

Clark Y Clark Y is the name of a particular airfoil profile, widely used in general purpose aircraft designs, and much studied in aerodynamics over the years. The profile was designed in 1922 by Virginius E. Clark using thickness distribution of the Germa ...

airfoils, braced with N-type interplane struts. ;KS Small Survey Aircraft: A modification of the KKY-2 into a civil photographic survey aircraft for the Department of Railways. It had additional large windows in the cabin sides behind the wing trailing edge and another in the cabin floor, a survey camera and seats for a survey crew of three. Two were built in 1939.

Specifications (KKY)

References

{{Tachikawa aircraft Biplanes Single-engined tractor aircraft 1930s Japanese military transport aircraft KKY Aircraft with fixed conventional landing gear