The Nakajima Ki-4 was the last

biplane A biplane is a fixed-wing aircraft with two main wings stacked one above the other. The first powered, controlled aeroplane to fly, the Wright Flyer, used a biplane wing arrangement, as did many aircraft in the early years of aviation. While ...

reconnaissance aircraft A reconnaissance aircraft (colloquially, a spy plane) is a military aircraft designed or adapted to perform aerial reconnaissance with roles including collection of imagery intelligence (including using photography), signals intelligence, as ...

of the

Japanese Imperial Army The was the official ground-based armed force of the Empire of Japan from 1868 to 1945. It was controlled by the Imperial Japanese Army General Staff Office and the Ministry of the Army, both of which were nominally subordinate to the Emperor o ...

. It saw combat service in

Manchukuo Manchukuo, officially the State of Manchuria prior to 1934 and the Empire of (Great) Manchuria after 1934, was a puppet state of the Empire of Japan in Northeast China, Manchuria from 1932 until 1945. It was founded as a republic in 1932 afte ...

and in

north China North China, or Huabei () is a List of regions of China, geographical region of China, consisting of the provinces of Beijing, Tianjin, Hebei, Shanxi and Inner Mongolia. Part of the larger region of Northern China (''Beifang''), it lies north ...

during the early stages of the

Second Sino-Japanese War The Second Sino-Japanese War (1937–1945) or War of Resistance (Chinese term) was a military conflict that was primarily waged between the Republic of China and the Empire of Japan. The war made up the Chinese theater of the wider Pacific Th ...

Design and development

The Ki-4 was initially produced by Nakajima in response to a 1931 specification for a high-performance

that could also be used in the light

ground support In military tactics, close air support (CAS) is defined as air action such as air strikes by fixed or rotary-winged aircraft against hostile targets near friendly forces and require detailed integration of each air mission with fire and moveme ...

role. After evaluating aircraft from

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...

and the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

, the

Imperial Japanese Army Air Force The Imperial Japanese Army Air Service (IJAAS) or Imperial Japanese Army Air Force (IJAAF; ja, 大日本帝國陸軍航空部隊, Dainippon Teikoku Rikugun Kōkūbutai, lit=Greater Japan Empire Army Air Corps) was the aviation force of the Im ...

selected a new design by the domestic Nakajima Aircraft Company. The

prototype A prototype is an early sample, model, or release of a product built to test a concept or process. It is a term used in a variety of contexts, including semantics, design, electronics, and Software prototyping, software programming. A prototyp ...

was test flown in May 1934. The Nakajima Ki-4 was a biplane design with staggered wings and fixed divided

landing gear Landing gear is the undercarriage of an aircraft or spacecraft that is used for takeoff or landing. For aircraft it is generally needed for both. It was also formerly called ''alighting gear'' by some manufacturers, such as the Glenn L. Martin ...

. It was powered by one Nakajima Ha-8, nine-cylinder, air-cooled

radial engine The radial engine is a reciprocating type internal combustion engine configuration in which the cylinders "radiate" outward from a central crankcase like the spokes of a wheel. It resembles a stylized star when viewed from the front, and is ca ...

. Maximum speed was and maximum take-off weight . It was armed with up to four 7.7 mm (.303 in)

machine gun A machine gun is a fully automatic, rifled autoloading firearm designed for sustained direct fire with rifle cartridges. Other automatic firearms such as automatic shotguns and automatic rifles (including assault rifles and battle rifles) a ...

s, two fixed to fire forward, synchronized with the

propeller A propeller (colloquially often called a screw if on a ship or an airscrew if on an aircraft) is a device with a rotating hub and radiating blades that are set at a pitch to form a helical spiral which, when rotated, exerts linear thrust upon ...

, and one or two more mounted dorsally on a flexible mount. The maximum bomb load was . A total of 516 units were produced, 333 by Nakajima between March 1934 and February 1939, and 57 under license by

Tachikawa Aircraft Company Ltd was an aircraft manufacturer in the Empire of Japan, specializing primarily in aircraft for the Imperial Japanese Army Air Force. It was based at Tachikawa, in Tokyo Prefecture. History Tachikawa Aircraft In November 1924, Ishikawajima Shipyar ...

and another 126 by Manshū in

(

Manchuria Manchuria is an exonym (derived from the endo demonym " Manchu") for a historical and geographic region in Northeast Asia encompassing the entirety of present-day Northeast China (Inner Manchuria) and parts of the Russian Far East (Outer Manc ...

Operational history

The first Ki-4s began equipping

units in 1935 and were an active part of Japanese fighter squadrons for a number of years thereafter. The Ki-4s saw substantial service in the early stages of the Second Sino-Japanese War from 1938. They also functioned as light

ground-attack aircraft An attack aircraft, strike aircraft, or attack bomber is a tactical military aircraft that has a primary role of carrying out airstrikes with greater precision than bombers, and is prepared to encounter strong low-level air defenses while pres ...

in the support of advancing Japanese ground troops. However, these biplanes were vulnerable to even the oldest and slowest moving enemy fighters. By the time of the entry of Japan into

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

, the Ki-4s were regarded as obsolete. A number were still retained for use in the supply and

liaison Liaison means communication between two or more groups, or co-operation or working together. Liaison or liaisons may refer to: General usage * Affair, an unfaithful sexual relationship * Collaboration * Co-operation Arts and entertainment * Li ...

role from 1941, and others were transferred to the

Manchukuo Air Force The Manchukuo Imperial Air Force (') ( was the air force of the Empire of Manchuria, a puppet state of Imperial Japan. The air force's predecessor was the Manchukuo Air Transport Company (later renamed the Manchukuo National Airways), a parami ...

, but those that had not been lost in service served briefly as elementary trainers or

target tug A target tug is an aircraft which tows an unmanned drone, a fabric drogue or other kind of target, for the purposes of gun or missile target practice. Target tugs are often conversions of transport and utility aircraft, as well as obsolescent comb ...

s before being scrapped. All of the Ki-4s were removed from active service by 1943. Two Ki-4s were tested as

seaplane A seaplane is a powered fixed-wing aircraft capable of takeoff, taking off and water landing, landing (alighting) on water.Gunston, "The Cambridge Aerospace Dictionary", 2009. Seaplanes are usually divided into two categories based on their tec ...

s, one with twin floats and the other with one main and two stabilizing floats, but neither version was placed into production.

Variants

* Ki-4 (Army Type 94 Reconnaissance Aircraft)

Operators

; *

Specifications (Ki-4)

References

;Notes ;Bibliography * *

External links

History of Nakajima Aircraft

Operations Manual for Type 94 Reconnaissance Plane – National Diet Library
{{Japanese Army Aircraft Designation System Ki-04, Nakajima Ki-004 Single-engined tractor aircraft Biplanes Aircraft first flown in 1933