Nakajima Ki-43 Hayabusa
Single-seat fighter built by Nakajima for the Imperial Japanese Army Air Service and flown from 1941 to the end of the Second World War. Exceptionally manoeuvrable but lightly armed and, at first, built without pilot armour or self-sealing fuel tanks, the Hayabusa — code-named Oscar by the Allies — was the Japanese Army's most numerous fighter, with more than 5,900 built.
Why It Mattered
The Ki-43 Hayabusa was the Imperial Japanese Army's most numerous fighter of the Second World War, built in greater numbers than any other Japanese Army type. It appeared wherever the army fought, from China to the South Pacific and the home islands. Allied pilots who first met it in 1941 were surprised by its agility, because Allied intelligence had badly underestimated what Japan's aircraft industry could produce. Allied reporting names gave it the code name Oscar. By late 1943 newer Allied fighters outclassed it, yet it remained in production and in front-line service until the war ended.
Design Notes
The Ki-43 began with an army specification issued to Nakajima in December 1937 for a successor to the Ki-27. The army wanted more speed, a faster climb and greater range, but insisted the new fighter manoeuvre as well as the Ki-27 it replaced. A team led by Hideo Itokawa rolled out the first prototype within a year, and flight tests began in January 1939. Army test pilots then criticised the prototype's manoeuvrability, and many saw its retractable landing gear as an encumbrance that added needless weight. Nakajima salvaged the design, most tellingly with 'combat' flaps beneath the wing centre section that shrank the turning circle dramatically. The agility had a price: a light, tidy airframe around a relatively small engine, only two machine guns, and, at first, no pilot armour and no self-sealing fuel tanks.
Operational History
The Ki-43 entered service in late 1941, and forty of the fighters entered combat in China shortly before Pearl Harbor. In the war's opening phase it was superior to any opposing fighter it encountered, out-turning the aircraft the Allies could field. The Ki-43-II, introduced in November 1942, added the cockpit armour and self-sealing tanks the first model had lacked, and in 1943 a second production line opened at Tachikawa to meet demand. More than 5,900 Hayabusas fought over China, Burma, India, the Malay Peninsula, New Guinea and the Philippines, and in defence of the Japanese home islands. Total production is put at 5,919 aircraft, which would make it the second-most produced Japanese fighter of the war after the Mitsubishi A6M Zero. Its lightness became a liability once the Allies fielded heavily armed fighters such as the P-38 Lightning: P-38 pilots reported Oscars exploding after only a short burst of fire. In the final months of the war, many Ki-43s were expended in kamikaze missions against the American fleet.
Afterlife
In Vietnam, French forces put Hayabusas the Japanese had left behind back into service with two of their units. In the Dutch East Indies, Ki-43s left behind were taken over by the newly declared Indonesian government. Original survivors are now few. The Smithsonian's Ki-43-IIb, acquired in December 1959, spent years on loan with other museums and has been on display at the Pima Air & Space Museum in Arizona since 2008. A Ki-43-I built in November 1942 was restored in New Zealand during the 1990s and is now part of the Flying Heritage & Combat Armor Museum in Washington. Rebuilds from wrecks recovered in the Kuril Islands have returned the shape to the air: one, completed in 2004, joined the Erickson Aircraft Collection in Oregon.