Ki-43 (Family)

Description

The Nakajima Ki-43, officially designated Army Type 1 Fighter, was the most numerous of all single-seat fighters used by the Imperial Japanese Army in World War II. While operating in Malaysia and Burma the plane received the codename "Jim" and in the Pacific Theatre it received the allied codename "Oscar". The codename "Oscar" was eventually selected as the official codename for the airplane by the Allies.

Nicknames:

• ▅ - Hayabusa (隼, Peregrine Falcon)
• ▃ - Jim
• ▃ - Oscar

Development History

In early 1937 the Army recognized that its current fighter the Ki-27 (Army Type 97) would not be able to compete against new designs that were starting to enter production around the world such as the Bf 109 in Nazi Germany. It was also recognized that the Ki-27 was having to perform an extremely varied set of missions, from air supremacy against other fighters, to bomber interception, and that a single new aircraft type might not be able to accomplish all of the army’s required missions in the future. With this in mind, the Army decided to request two new fighter aircraft types to meet its future needs. The first would be a direct successor to the Ki-27: a low altitude fighter that would focus on defeating enemy planes; while the second would be a more heavily-armed high altitude plane that would focus on destroying enemy bombers.

Instead of going through the normal process of requesting manufacturers to submit designs, the Army instead directly contracted Nakajima to produce a replacements for their Ki-27 (Army Type 97) fighter. This was due to political and economic pressures from the aircraft design companies as the cost of failed bids was something could bankrupt a company. With the lack of a bidding process the army laid rigid requirements for this new low altitude dog-fighter to Nakajima. The new aircraft type was to have a top speed of 311 mph, to be able to reach 16,405 ft within five minutes, to have a minimum range of 500 miles, it was to be armed with two 7.7 mm machine guns, and to not lose any of the manoeuvrability of the Ki-27. These requirements proved to be unachievable using the currently available technology and plane ended up being an airplane designed by compromise instead of purpose designed dog fighter the army wanted.

The first prototype of what was to become the Ki-43 was completed in December 1938 with 2 more following soon after in 1939. Upon testing by army pilots the compromise nature of the plane became instantly apparent and it was found that these airplanes did not live up the Army's expectations for a successor to the extremely successful Ki-27. The complaints from test pilots included that the plane was not manoeuvrable enough, hard to control, and had visibility issues. To make matters worse the plane performed worse in almost every aspect then an improved version of the Ki-27 also being developed by Nakajima. It was decided by the army that the aircraft was not something they were interested in and stopped support of its development. The one positive to come out of the testing of the initial 3 prototypes was the Nakajima Ha-25 engine which was seen by the army as an excellent engine and was immediacy ordered into production. The Ha-25 would even go on to create the Sakae series of engines that would be used in the navy’s new fighter the A6M.  

Following the evaluation of the initial 3 prototypes, Nakajima would continue development of the aircraft on its own. Without the stringent requirements of army guiding the development a more focused design process could begin. Nakajima would construct 10 test aircraft with various modifications in order to address the armies concerns with the initial 3 prototypes. The changes tested included giving the fighter the more powerful HA-105 engine, replacing the 7.7 mm machine guns with 12.7 mm machine guns, upgrading the outer skin to a treated duralumin, a narrower fuselage, redesigned tail surfaces, modifications to the wing design, and the introduction of “butterfly” flaps. These were flaps that could be deployed in order to increase the controllable wing surface allowing the plane to overcome its lack of manoeuvrability that the Army had issue with and transformed the plane into a successful fighter design.

Vehicles

Ki-43-I After the 10 improved prototypes were tested the Army settled on what they saw was the optimum configuration and requested that the production aircraft be equipped with the Nakajima Ha-25 engine. The final design entered production as the Ki-43-Ia (Army Type 1 Fighter Model 1A) with the first example completing production in April 1941. This model was soon replaced with the Ki-43-Ib (Army Type 1 Fighter Model 1B) which replaced one of the 7.7 mm machine guns with a 12.7 mm machine gun which was also soon replaced by the Ki-43-Ic (Army Type 1 Fighter Model 1C) which was equipped with two 12.7 mm machine gun.

Ki-43-II After some time in the field, the Ki-43 was to receive a major upgrade based on feedback from pilots, which included replacing the Ha-25 engine with the more powerful Ha-115 engine, a two stage supercharger, pilot armour, self-sealing fuel tanks and many more minor improvements. The first prototype of what was to become the Ki-43-II (Army Type 1 Fighter Model 2) was completed in February 1942.

▃Ki-43-II In late 1942, the Australian Army managed to capture a intact example of a Ki-43 while fighting the Japanese Army in Papua New Guinea. It was quickly shipped back to Australia for testing where it ended up in the hands of the Technical Air Intelligence Unit who managed to repair it using parts from downed airplanes. It was painted in US livery and was used to test its performance against Allied planes. After testing by the Technical Air Intelligence Unit it was shipped to the United States for further evaluations.

Ki-43-III otsu The last major modification of the Ki-43 was done in 1944, combining the minor modifications of the IIa and IIb with the more powerful Nakajima Ha-115-II engine. These minor modifications over the Ki-43-II included a reduced wing-span (improving the plane's low and medium speed performance), increased pilot armour, improved oil cooler, and modified carburetor intake. This new Ki-43-IIIa (Army Type 1 Fighter Model 3A) entered production in October 1944 with approximately 1,000 being completed before the war ended.

␗Ki-43-III ko After the end of the war, a number of nations used the Ki-43, including the Indonesian People's Security Force who used them against the Dutch, and the French who used them against Communist forces in Indochina. One such post-war user was the Nationalist Chinese Air Forces who operated captured Ki-43 in the 6th group. These saw use against the Communist Chinese forces in the Chinese Civil War and 5 were eventually captured and used by the Chinese Communist Air Force until 1952.