Nakajima Ki-27


The Nakajima Ki-27 was the main fighter aircraft used by the Imperial Japanese Army Air Force up until 1940. Its Allied nickname was "Nate", although it was called "Abdul" in the "China Burma India" theater by many post war sources; Allied Intelligence had reserved that name for the nonexistent Mitsubishi Navy Type 97 fighter, expected to be the successor to the carrier-borne Type 96 with retractable landing gear and an enclosed cockpit.

Design and development

In 1935, the Imperial Japanese Army held a competition between Nakajima, Mitsubishi, and Kawasaki to design a low-wing monoplane to replace the Kawasaki Ki-10 biplane. The new fighter was to have also a better performance than the experimental Mitsubishi Ki-18.
The results were the Nakajima Ki-27, the Kawasaki Ki-28, and the Mitsubishi Ki-33. The Nakajima design was based on its earlier Ki-11 monoplane fighter which lost to the Ki-10 in the Type 95 Fighter competition. When the follow-up Nakajima Ki-12 proposal with a liquid-cooled engine and retractable landing gear was deemed too complex by the Japanese officials, the Ki-27 was designed by Koyama Yasushi to have an air-cooled radial engine and fixed landing gear. The aircraft had the Nakajima trademark wing with a straight leading edge and tapered trailing edge which would reappear again on the Ki-43, Ki-44, and Ki-84.
The Ki-27 made its first flight on 15 October 1936. Although it had a slower top speed and worse climb performance than its competitors, the Army chose the Nakajima design for its outstanding turning ability granted by its remarkably low wing loading. The Army ordered 10 pre-production samples for further testing, which featured an enclosed cockpit with sliding canopy and larger wings.
The type was officially accepted into service in 1937 as the Army Type 97 Fighter. In addition to Nakajima, the Ki-27 was also manufactured by Tachikawa Aircraft Company Ltd and Manshukoku Hikoki Seizo KK, with a total of 3,368 built before production ended in 1942.

Operational history

The Ki-27 was the Imperial Japanese Army Air Force's main fighter until the start of World War II. When placed into combat service over northern China in March 1938, the Ki-27 enjoyed air superiority until the introduction of the faster Soviet-built Polikarpov I-16 fighters by the Chinese.
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In the 1939 Battle of Khalkhin Gol against the USSR in Mongolia, the Ki-27 faced both Polikarpov I-15 biplane and Polikarpov I-16 monoplane fighters. In the initial phase of the conflict, its performance was a match for the early model I-16s, and was considerably superior to the I-15 biplane. With better trained Ki-27 pilots, the IJAAF gained aerial superiority. The Ki-27 was armed with two 7.7 mm Type 89 machine guns and as with most aircraft of the period, lacked armor protection for the pilot and self-sealing or fire suppression in the fuel tanks.
Later, the Soviet Air Force received improved I-16s. The faster, more heavily armed and armored I-16 now nullified the Ki-27's advantages and it could now escape from the Ki-27 in a dive. The VVS introduced new tactics consisting of flying in large tightly knit formations, attacking with altitude and/or speed advantage and hit-and-run tactics much as Claire Chennault would later formulate for the 1941-era Flying Tigers.
Japanese losses mounted but despite this they claimed 1,340 aircraft. Japanese losses numbered 120 while the Russians claimed 215 vs. a peak Japanese strength of 200 fighters. Top scoring pilot of the incident and top scoring IJAAF pilot on the Ki-27 and overall World War II IJAAF ace was Warrant Officer Hiromichi Shinohara, who claimed 58 Soviet planes whilst flying Ki-27s, only to be shot down himself by a number of I-16s on 27 August 1939.
The preference of Japanese fighter pilots for the Ki-27's high rate of turn caused the Army to focus excessively on manoeuvrability, a decision which later handicapped the development of faster and more heavily armed fighters. The Ki-27 served until the beginning of World War II in the Pacific, escorting bombers attacking Malaya, Singapore, Netherlands East Indies, Burma and the Philippines.
The type also saw extensive action against the American Volunteer Group in the early months of the war. Soon outclassed by the American Curtiss P-40 Warhawks, the Ki-27 was replaced in front line service by the Nakajima Ki-43, while surviving examples continued to serve as a trainer.
The Ki-27 was also exported for use with Manchukuo and Thai armed forces, seeing combat with both. In Thai service, Ki-27s reportedly damaged two North American P-51 Mustangs and shot down one Lockheed P-38 Lightning.
In the final months of the war, desperate lack of aircraft forced the Japanese to utilize all available machines and the Ki-27 and 79 were no exception. Some were equipped with up to of explosives for kamikaze attacks, but some were redeployed as fighters, suffering terrible losses as on 16 February 1945 when the 39th Educational Flight Regiment scrambled 16 Ki-79 trainers from Yokoshiba Airfield to oppose a massive air raid from U.S. Task Force 58 carrier group, losing six aircraft with more damaged and five pilots killed, in return damaging at least one Hellcat and possibly downing a second.

Variants

Data from
;Nakajima Army Type 97 Fighter
; Nakajima Type PE
; Nakajima Ki-27
; Nakajima Ki-27-Kai Prototype
; Ki-27a
; Ki-27a-Kai
; Ki-27b
; Ki-27b-Kai
; Nakajima Ki-27-Kai
; Mansyū Ki-79
; Mansyū Army Type 2 Advanced Trainer

Operators

World War II

; Reformed Government of the Republic of China
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Two aircraft survive today: