Nakajima Ki-27 of the Akeno Army Flying School, ca. winter 1941/42 (see Bueschel 1970)
The Nakajima Ki-27(九七式戦闘機?,Kyūnana-shiki sentōki, or Type 97 Fighter) was the main fighter aircraft used by the Imperial Japanese Army Air Force up until 1940. Its Alliednickname was "Nate", although it was called "Abdul" in the "China Burma India" (CBI) 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 Type 96 carrier-borne A5M with retractable landing gear and an enclosed cockpit.
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 (Ki-27a) for further testing, which featured an enclosed cockpit with sliding canopy and larger wings.
Nakajima Ki-27b of Kenji Shimada, commander of the 1st Chutai of the 11th Sentai, Battle of Khalkhyn Gol June 1939
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.
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 (.303 in) 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 (with twin wing-mounted 20mm ShVAK cannons) 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 (high-energy) tactics much as Claire Chennault would later formulate for the 1941-era Flying Tigers (likewise to fly against Japanese forces).
Japanese losses mounted but despite this they claimed 1,340 aircraft (six times the admitted Soviet losses and three times as many as Soviet aircraft admitted to being in the theatre), though similar discrepancies were common worldwide before gun cameras became widespread. Japanese losses numbered 120 (including Ki-10s) 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 OfficerHiromichi Shinohara, who claimed 58 Soviet planes (including an IJAAF record of 11 in one day) 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 (where it initially fared poorly against the Brewster F2A Buffalo).
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 500 kg (1,100 lb) 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.
Private-venture experimental aircraft with Nakajima Ha.1a engine.
Prototype version with armament in response to IJAAF specs, two aircraft built.
Nakajima Ki-27-Kai Prototype
Pre-production units with armament and heavier Ha.1b engine, 10 aircraft built.
First production version. Approximately 565 aircraft built.
Trainer version converted from existing production. Approximately 150 aircraft converted.
Ki-27b (Army Type 97b Fighter)
Improved canopy, oil cooler and provision for 4 × 25 kg (55 lb) bombs or fuel tanks under the wings. A total of 1,492 built, including 50 by Tachikawa Aircraft Company Ltd.
Trainer version converted from existing production. Approximately 225 aircraft converted.
Experimental lightened version developed as an interim solution when Ki-43 development was delayed, top speed 475 km/h (295 mph); two aircraft built).
Trainer version, built by Manshūkoku Hikōki Seizo KK with a 510 hp Hitachi Ha.13a-I or Ha.13a-III engine. A total of 1,329 aircraft built in four sub-versions (The single seat Ki-79a (Ha.13a-I) and Ki-79c (Ha.13a-III) and the two-seat Ki-79b (Ha.13a-I) and Ki-79d (Ha.13a-III)).
In 1945, Indonesian People's Security Force (IPSF) (Indonesian pro-independence guerrillas) captured a small number of aircraft at numerous Japanese air bases, including Bugis Air Base in Malang (repatriated 18 September 1945). Most aircraft were destroyed in military conflicts between the Netherlands and the newly proclaimed-Republic of Indonesia during the Indonesian National Revolution of 1945-1949.
Two aircraft survive today:
A Nakajima Ki-27 in Tachiarai Peace Memorial Museum
One Ki-27 is preserved at the Tachiarai Peace Memorial Museum.