Peregrine Falcon - a bird of prey widely known as a graceful, speedy hunter. Nakajima aptly named the Ki-43 after this impressive raptor for the fighter served the Japanese Army in higher numbers than any other army type. Wherever the army fought, the Hayabusa flew overhead. The fighter surprised western pilots when they first encountered it because intelligence specialists vastly underestimated the capabilities of Japan's aircraft industry. Although not well known compared to the A6M Zero (see NASM collection), the Ki-43 was a formidable aircraft, particularly during the early war years.
Transferred from the Air National Guard.
Date: 1942 - 1945
Country of Origin: Japan
Other: 10ft 9 15/16in. x 29ft 2 3/8in. x 35ft 5 3/16in., 4210.8lb. (330 x 890 x 1080cm, 1910kg)
Monocoque all-metal construction
Single-engine, conventional layout with tailwheel-type landing gear.
Peregrine Falcon - a bird of prey widely known as a graceful, speedy hunter. Nakajima aptly named the Ki-43 after this impressive raptor for the fighter served the Japanese Army in higher numbers than any other type. Wherever the army fought, the Hayabusa flew overhead. The fighter surprised western pilots when they first encountered it because Allied intelligence specialists underestimated the capabilities of Japan's aircraft industry. Although not well known compared to the A6M Zero, the Ki-43 was a formidable aircraft, particularly during the early war years.
The Ki-43 originated in specifications that the Japanese Imperial Army issued to Nakajima Hikoki K. K. in December 1937. The army needed to replace the nimble Nakajima Ki-27, an open-cockpit, monoplane fighter later nicknamed NATE by the Allies. They wanted more speed (501 kph or 311 mph), better time to climb (5,000 m or 16,405 ft in 5 minutes), and a range of 1,288 km (800 mi). The specified armament comprised two 7.7 mm machine guns and the new airplane had to maneuver as well as the Ki-27. A team led by Hideo Itokawa took only a year to roll out the first prototype. Flight tests began in January 1939. A 925 horsepower engine powered the prototypes and the new fighter flew well but army test pilots criticized its maneuverability. Ironically, many army pilots viewed the retractable landing gear as an encumbrance that made the airplane unnecessarily heavy and less maneuverable.
For a time, it seemed that Nakajima would abandon the Ki-43. However, the firm decided to salvage the design and engineers replaced the single-stage supercharger with a two-stage unit to provide greater power at higher altitudes. They also added an all-round-vision canopy, a variable pitch propeller, and switched to a pair of 12.7 mm guns. Itokawa's team made their most significant change when they added 'combat' flaps beneath the wing center section. When the pilot deployed these tapered flaps at speed, they helped to pitch the airplane's nose up without generating too much drag, and the turning circle of the Ki-43 shrank dramatically.
The next round of evaluation left the test pilots highly impressed and the army ordered the Ki-43-I into production. Forty of the machines entered combat in China shortly before Pearl Harbor. After Allied pilots tangled with Hayabusas in both the China-Burma-India and South-West Pacific Theaters, intelligence teams codenamed the airplane OSCAR.
Like many Japanese combat aircraft of World War II, the first Ki-43s lacked both protective armor for the pilot and explosion-proof, or self-sealing, fuel tanks. Nakajima addressed both of these shortcomings, and incorporated other minor refinements, when the firm introduced the Ki-43-II in November 1942. Engineers also designed other variants including the Ki-43-IIb. The most distinguishing feature of this model was a major revision to the oil cooler. In previous models, two radiators cooled the oil. One unit lay inside the cowling ahead of the engine and the other fit around the propeller shaft behind the spinner. In the 'IIb, a single cooler was placed inside the carburetor duct, after the duct was enlarged to accommodate the new component. During 1943, the army demanded more OSCARs than Nakajima could produce, so a new production line was set up at Tachikawa. In all, more than 5,900 Hayabusa's fought in the skies above China, Burma, India, the Malay Peninsula, New Guinea, the Philippines and many other South Pacific islands, and the Japanese home islands. After the war, the French equipped two units based in Vietnam with Hayabusas abandoned by the Japanese.
In combat, the Hayabusa was superior to any opposing fighter it encountered in the initial part of the war. The OSCAR remained formidable even as more experienced Allied pilots and better aircraft entered the fray. Like the Zero, the OSCAR turned and stalled better than most fighters to see combat in the war. Low gross weight was an important factor in this performance. Nakajima achieved it by building a spare, tidy airframe powered by a relatively small engine. The company only installed two machine guns, and omitted pilot armor and self-sealing gas tanks. These sacrifices cost dearly when the Allies began to field airplanes with heavy firepower such as the Lockheed P-38 Lightning. The Lightning packed four 12.7 mm (.50 cal) machine guns and a 20 mm cannon. Many P-38 pilots commented on the tendency of OSCARs to explode after only a short burst of fire. The small engine propelling the K-43 also limited performance for it permitted Allied pilots flying faster airplanes to engage or decline combat at their discretion.
The NASM Ki-43-IIb is the last remaining OSCAR. During the late 1950s, the Air National Guard displayed the airplane at a base in New Mexico. After the Smithsonian acquired the artifact in December 1959, the Experimental Aircraft Association (EAA) Museum in Oshkosh, Wisconsin, borrowed the fighter, restored the exterior, and placed it on exhibit.