The first two regiments to be re-equipped with the Ki-43 were transferred to the Malaysia-Burma offensive region, where in early December 1941 they were ordered to take part in the Malaysia-Thailand landing operation. (A fighter regiment [sentai] consisted of three squadrons [chutai], with 9 aircraft each. Later, when fighters were used in pairs instead of trios, the squadron structure would change – each chutai then comprised 3 teams [shotai] with 4 aircraft apiece, and each sentai included one more squadron). The first encounter between the Ki-43 and Allied aircraft took place above Burma. Representing the Allies were the Curtiss P-40 Kitty Hawk of the US Volunteer Squadron and the Bruster Buffalo of the Royal Air Force 67th Fighter Division. The first serious battle involving Hayabusa took place on December 22, 1941 in Malaysia. 18 Ki-43 of the 64th fighter sentai intercepted 12 Buffalo of the Royal Air Force 453rd Squadron, destroying 5 and damaging 4 of the British aircraft, while losing only one of their own.
The effect of the Hayabusa’s appearance in the Pacific seat of war was even more powerful that that of the Zero, and its flight performance was a revelation. Least of all did the Allies expect to do battle with a monoplane capable of flying loops at such high speeds! Moreover, they could not fathom how such an aircraft managed to take off from a plot of water-logged ground, which the Allies would call an “airfield” only in the most advanced state of inebriation. The plane soon became the favorite aircraft of the Japanese army pilots.
But the future did not look so bright for the Ki-43. First of all, in the course of battle the main defect of the Hayabusa—its high vulnerability—came to light. The most flawed part of its design was its armor, or to be more precise, the utter lack thereof. To lower the plane’s overall mass, Itokawa had been compelled to do away with the armored back and fuel tank protection, a solution which ultimately led to heavy casualties. The weaponry in the form of two rifle-caliber machineguns could not stand up to the Allied fighters. It was necessary to begin improving the plane at once.
Owing to underproduction of 12.7mm Ho.103 machineguns, the version Ki-43-Ib, which was being produced in parallel with Ki-43-Ia, had to be equipped with only one such machinegun paired with 7.7mm type 89. Even though that was clearly not enough, the new version Ki-43-Ic with two 12.7mm machineguns appeared much too late. At the moment of its launch, the new plane was already obsolete and regarded as a mere transitional variant of the more sophisticated Ki-43-II model. By that time, the experimental engine Nakajima Ha.105 had already gone into mass production as the Ha.115 type 2. This very engine was installed on the new version. The engine’s take-off power was 1130 hp and it could reach 1150 hp at 2800 m altitude. It was equipped with a two-stage supercharger.
In November 1943, the new aircraft went into mass production as the Ki-43-IIa. The fighter was finally equipped with protection for the fuel tanks, as well as a 13mm armored back and an armored head-rest for the pilot. A three-bladed propeller replaced the former two-bladed one. Reinforcement of the wings made it possible to attach a pair of 200-l fuel tanks, thereby increasing the range to more than 500 km. The tanks could be replaced with 250-kg bombs.
Main army fighter Nakajima Ki-43-IIa type 1 model 2A with a three-bladed propeller.
Nakajima Ha.115 type 2 1130-hp engine with separate exhaust manifolds. Such engines were used on late models of the Ki-43-Iic.
One of the latest Ki-43-IIc models with the Ha.115 engine and separate exhaust manifolds. Under the wings are stationary pylons with 200-l fuel tanks attached.
In early 1943, the model 1 was taken out of production. A total of 716 aircraft had been made. To produce model 2, specialists of the Nakajima firm started up manufacturing in Tachikawa in addition to the Ohta factory. By late 1943, Hayabusa had become the most popular army fighter. The Ohta factory had reached its target rate of 135 aircraft per month, and the Tachikawa plant produced 420 aircraft that year. Production of model 2 surpassed all other planes in quantity and continued until the last day of the war.
Nevertheless, there was a growing realization that the plane was rapidly becoming obsolete, with prospects for modernization questionable at best. Replacement of Ki-43 as the main army fighter was set for the distant future. So in early 1944 engineers undertook the creation of a new Ki-43-IIIa model, which would differ from its predecessor in the more powerful Ha.115-II engine, with power of 1190 hp at take-off and 1230 hp at 2800 m altitude, and a two-stage supercharger. But work on this aircraft was discontinued after production of the pre-series group of 10 aircraft . Anyway, by that time, a replacement was already available – the Ki-84.
Until the end of the war, a total of 5918 Ki-43 fighters were manufactured. 5751 of these were transferred to the army. The Nakajima factory in Ohta produced 3238 aircraft, 3185 of which were sent to the army; the corresponding figures for Tachikawa and the Rekugun firm are 2631 and 2544, and 49 and 22 respectively.
The Hayabusa was the only aircraft to serve throughout the entirety of the war. It saw action on every front from the Okhotsk Sea to India and New Guinea and did battle in the skies over China, Burma, Thailand and Indonesia. It was needed everywhere and always, and it remained the favorite aircraft of the Japanese army pilots. Ki-43 played the most crucial part in the Burma campaign of the spring of 1944. It was even deployed in Manchuria to intercept the B-29s that were bombing Mukden. The Hayabusa will forever bear its nickname – “workhorse.”
Of course, as a fighter, the Ki-43 could not claim to be the acme of perfection. At the time of its launch, it was already obsolete and unable to compete with the latest masterpieces of foreign technology. The success of this aircraft stemmed from a combination of several factors: its unique horizontal maneuverability, the skill of the Japanese pilots, and, of course, the total air superiority of the Japanese air forces in the early stages of the war.
At this point in our chronicle, we must return to 1939 and say a few words about another aircraft. As it happened, the Army Air Force HQ assumed that the top priority in the new generation of fighters to take part in the coming war would be speed rather than maneuverability. So just in case, alongside the order for the Ki-43, the army leaders also submitted to Nakajima an order for a fast and unmaneuverable (in Japanese terms) interceptor. It is worth noting, that the order envisioned the creation of a pure interceptor, able to challenge the enemy bombers.
The head of the engineering team was chief engineer Tamura Koyama, who participated closely in the development of Ki-27. First of all, Koyama decided to equip the plane with a more powerful engine than that of the Ki-43. He chose the 14-cylinder “double star” Nakajima Ha.41 with 1250 hp take-off power. The engine was extremely cumbersome and intended mainly for bombers, so fitting it into the fighter’s miniature frame was a challenging task. Nevertheless, the engineers pulled it off brilliantly. The large-diameter engine was well-matched with a small-section fuselage, and the fin was moved backwards to compensate for the engine’s mass. On the whole, the aircraft would very much resemble Ki-43, if not for the very short wings. Of course, the fighter was equipped with numerous technological innovations: fully retractable landing gear, radio station, 360-degree field-of-view canopy, armor, protected tanks, and Fowler-type combat flaps.
In August 1940 the first prototype of the new fighter took off. But the tests revealed significant flaws. The speed fell short of expectations by almost 50 km/h, and it took almost 6 minutes to reach 5000 m! Due to the large wing load, the plane’s landing speed was excessive, necessitating a long runway. It was proposed to Nakajima that the project be abandoned as fruitless, but the engineers managed to find the means to continue what they had started. A year passed before substantial modifications enabled the prototype to reach a top speed of a 570 km/h in July 1941. After a number of final improvements, the plane was able to fly without weaponry at 626 km/h.
Thus Nakajima received an order to build seven pre-series aircraft, named “high-speed fighter-interceptor Ki-44 type 2.” The aircraft also bore the name “Shoki” (“Demon”), and later the Allies nicknamed it “Tojo”, after the Japanese admiral. In November 1941, the 7 pre-series aircraft together with the two enhanced prototypes, were assigned to the 47th separate experimental squadron and transferred to the battle region in Malaysia for testing under real-life conditions. The Ki-44 weaponry consisted of two 7.7mm type 89 machineguns under the engine hood and two 12.7mm Ho.103 machineguns in the wings. In the Demon’s initial encounter with enemy forces in early 1942, Captain Kuro shot down an Australian Buffalo.
A first series Nakajima Ki-44 type 2 model 1 Shoki (“Tojo”) with a central external 200-l fuel tank and telescopic sight.
