The Nakajima Ki-43-I Hayabusa (隼, "Peregrine Falcon") "Hei" (a.k.a Army Type 1 Fighter) is a single-engine land-based tactical fighter. It's allied reporting name is "Oscar", but it was often referred to as the "Army Zero" by allied pilots because it bore a certain resemblance to the legendary A6M. Through out the various episodes of the anime, it serves as the main fighter plane of the Kotobuki Flying Corps.
Designed by Hideo Itokawa, the Ki-43 was first produced in 1937 as a prototype in order to replace the aging Nakajima Ki-27. The specification called for a top speed of 500 km/h (311 mph), a climb rate of 5,000 m (16,400 ft) in five minutes and a range of 800 km (500 mi). Maneuverability was to be at least as good as that of Ki-27.
However, when Japanese test pilots first got their hands on the prototype Hayabusa, they were disappointed. They claimed that the Ki-43 was not only less maneuverable than the Ki-27, but also hardly any faster. In order to combat these drawbacks, Nakajima produced a series of progressively enhanced prototypes throughout 1939 and 1940. These changes involved a major weight saving program, a slimmer fuselage with the tail surfaces moved further aft and a new canopy. Crucially, the 11th prototype introduced the unique differential "butterfly" maneuvering Fowling Flaps, drastically reducing the Hayabusa's truing radius. The 13th prototype combined all these changes and test results were satisfactory. Nakajima was instructed to put the Ki-43 under mass production.
Production of the Ki-43 began November 1939, the first models were given the designation Ki-43-I. The Hayabusa went on to perform spectacularly, seeing combat in China, Burma, the Malay Peninsula, New Guinea, the Philippines, South Pacific islands and the Japanese home islands. Despite its armor being rated at next to none, the agile aircraft proved to be very difficult to hit for slower and more cumbersome American fighters, it was claimed that the Hayabusa shot down more Allied aircraft than any other Japanese fighter and almost all the JAAF's aces achieved most of their kills in it.
The Hayabusa's most notable advantage is its outstanding agility, this is in many ways thanks to its light weight construction. The Hayabusa is also easy to fly and has an excellent rate of climb. The pilots of Kotobuki Flying Corps soon came to love the Hayabusa's pleasant flight characteristics, the aircraft's maneuverability combined with their abundant dogfighting skills allowed the Kotobuki to go toe to toe with opponents flying far more advanced and potent aircrafts, even standing its ground against the likes of the Ki-61 and the Ki-84, aircrafts that were designed to replace the Hayabusa.
Much like most other Yufang aircraft designs, the Ki-43 Hayabusa's amazing agility comes at a price: having nearly no armor to protect the plane's fragile airframe. A few well placed shots will be enough to structurally damage the Hayabusa or outright shatter it. The lack of self-sealing fuel tanks also made the Hayabusa prone to catching fire or even explode. The major weak spots of the Hayabusa are closely grouped toward the front of the plane: the engine, the controls, the fuel tanks and the pilot him/herself.
Another of the Hayabusa's major drawbacks is its poor armament: only 2 12.7 mm machine guns, this flaw is shared with nearly all models of the Hayabusa and it becomes especially glaring when compared to most other fighters the Ki-43 encountered in the skies. Most, such as the A6M Zero, the Ki-61 Hein and the N1K-J Shiden are armed with powerful 20 mm cannons. While the issue of poor firepower is more severe in the Yufang's home world, it become evident for the pilots of the Kotobuki as well in Episode 8 where they struggled to even damage the better armored Ki-84 Hayates and in Episode 10 where they went toe to toe against heavily armored G10N Fugaku bombers.
As of now, the Kotobuki Flying Corps are the only known flying group known to operate Ki-43-Is, this lead to some pilots (before seeing them in action) to underestimate them due to their outdated gear. Each of the six Ki-43s share the basic silver & green color scheme but are customized to reflect their pilot's personality and experience.
- Kirie's Ki-43 sports a red falcon emblem on its rudder, the exact same emblem seen on Ol' Sabu's A6M3. Its wingtips are adorned with red primary wing father patterns to match the red falcon on the tail. The propeller hub tip is colored red.
- Emma's Ki-43 has a much denser green camo pattern, but the pattern is absent on the sides of her fuselage. The tail emblem of her plane consists of a blue scythe positioned above a white rose. Blue vine patterns decorate the side and wingtips, her propeller cap is colored light blue at the tip.
- Kate's Ki-43 sports a somewhat faded green camouflage. Her tail emblem is a purple double headed arrow while her wingtips are decorated with purple arrows, her propeller cap is colored a light shade of violet.
- Reona's Ki-43 shows the most amount of usage amongst the squad's six aircrafts. Her camo patterns are even more worn out compared to Kate's and the side of the fuselage shows various replaced body panels. Her tail emblem consists of a green lightning bolt over three thin horizontal green stripes (all with white linings). Two lime green stripes with white linings run along the aircraft's wings forming a "V" shaped pattern, her propeller cap is entirely green.
- Zara's Ki-43 is arguably the most extravagant looking one, the green camo patterns are thicker and more well kept, the sides, wings and tail of her aircraft are all decorated with curved golden patterns taking shapes of wings, wind and stars. Her propeller hub is also gold tipped.
- Chika's Ki-43's green camo pattern resembled those of the rolling clouds. Her tail emblem is a baby seal, sowing her interest in oceanic creatures. A bright pink lightning bolt runs down the tail of her aircraft, her wingtips are also decorated with pink lighting bolt patterns. Her propeller cap is also colored pink.