Let's begin with what Francillon has to say about the "Hayabusa":
"Design work on the Hayabusa began in December 1937 when the Army, giving up their long-standing policy of awarding competitive contracts to Japanese manufacturers, instructed Nakajima Hikoki K.K. to design a single-seat fighter to supersede the Army Type 97 Fighter (Nakajima Ki-27)."
And about the "Shoki":
"Shortly after instructing Nakajima to proceed with the design of the Ki-43, the Koku Hombu gave them their specification for an interceptor fighter. In a pronounced departure from previous Japanese standards, speed and climb rate were emphasized at the expense of manoeuvrability. The Ki-44, as the project became known,..."
The English Wikipedia entries heavily rely on Francillon and basically repeat the above.
But let's see what the Japanese Wikipedia has to say about the mindset behind the development of these two fighters and the "Army Aviation Weapons Research Policies":
The Nakajima-built Type 97 Fighter (Ki-27 "Nate"), officially adopted in December 1937, featured an ambitious design—the Army's first all-metal, low-wing monoplane—despite its conservative fixed landing gear. It was an excellent dogfighter with superior climb rates and maneuverability. However, by the time the Type 97 appeared, the Bf 109 (Germany) and Spitfire (UK)—both featuring retractable landing gear—had already emerged in Europe, prompting the Army to explore the development of new fighters.
In the "Army Aviation Weapons Research Policy" for the 1937 fiscal year—formulated by the Army Aviation Headquarters while the Ki-27 was under development—single-seat fighters were defined in two categories: "machine-gun equipped" and "autocannon equipped." The aircraft developed in accordance with these specifications were the Ki-43 (for the former category) and the Ki-44 (for the latter).
The "Army Aviation Weapons Research Policy" for the 1938 fiscal year further refined these categories into "Light Single-Seat Fighter" and "Heavy Single-Seat Fighter" and added a third: the long-range two-seat fighter based on the concept of a twin-engine multi-role fighter.
Based on this, instructions for the research and development of both "light" and "heavy" fighters were issued to Nakajima, Kawasaki, and Mitsubishi; Nakajima’s responses were the Ki-43 (Type 1 Fighter "Hayabusa") for the light fighter category and the Ki-44 (Type 2 Fighter "Shoki") for the heavy fighter category (Chief Engineer Koyama Yasushi led the design teams for both). Aoki Kunio, an engineer on the Ki-43 design team, stated that while the "Hayabusa" was also intended to be a heavy fighter (modeled after the Bf 109), the team's lack of experience in heavy fighter development resulted in it becoming a light fighter instead.
Although proponents of light fighters argued that the Ki-44 was unnecessary, the development process—which had previously stalled—was revitalized following lessons learned during the Nomonhan Incident in 1939. Combat experience showed that Soviet Red Air Force fighters were effectively employing "hit-and-run" tactics, creating a recognized need for a cutting-edge fighter capable of executing such attacks and pursuing high-speed aircraft like the I-16.
According to FAOW #65 the attached photo features:
"the third (aircraft number 4303) of the three Nakajima Ki-43 "Hayabusa" (Oscar) prototypes built in 1939. Its shape differs considerably from that seen in full-scale models and drawings due to modifications and upgrades made to the prototype aircraft from late autumn of 1940 to early 1941. The rear fuselage, canopy, and the position of the slightly longer antenna mast, among other things, became almost identical to the production model. However, the flaps were still of the split type, and the armament covers and muzzles remained for 7.7mm guns. The reason why only two fuselage stripes were painted on the third prototype is unknown."
But note the very unusual yellow (?) band starting from the canopy side and continuing on the wing.
Unlike the Ki-43, the Ki-44 faced delays; the Army and the manufacturers lacked experience with heavy fighters, making it difficult even to finalize basic specifications, and consequently, its development schedule was prioritized below that of the Ki-43. Before the Army had even issued its formal performance requirements, Nakajima proceeded with development by setting the Bf 109 as a benchmark. According to Aoki, the "Shoki" was intended as an insurance measure in case the "Hayabusa" was not adopted, and it possessed strong characteristics of an experimental aircraft. This nature allowed Nakajima to incorporate new technologies and concepts into the "Shoki".
Drawing on lessons from the Nomonhan Incident and research into Western aircraft trends, the Army recognized the importance of protective measures. Consequently, the Ki-44 was equipped not only with fire-resistant fuel tanks (self-sealing tanks featuring a multi-layered rubber casing to prevent leakage and ignition upon impact—a feature the Army had previously ordered Nakajima to install starting with the Ki-43 prototype) but also, for the first time on a Japanese fighter, a 13 mm thick armor plate behind the pilot's seat for protection. This armor plating covered the headrest and backrest areas, with a total weight of 60 kg.
At the initial development stage, the armament requirements called for one fixed cannon and two fixed machine guns. The configuration consisted of two 12.7 mm cannons (Ho-103 Type 1 Fixed 12.7 mm Cannon)—utilizing newly developed high-explosive ammunition—mounted in the wings, and two conventional 7.7 mm machine guns (Type 89 Fixed Machine Gun) in the nose. It also featured a retractable tailwheel, a rarity among Army aircraft.
The prototype made its maiden flight on June 4, 1940. However, due to insufficient engine performance and numerous technical issues, various improvements were implemented. However, compared to conventional fighters, it was inferior in turning performance; the large-diameter engine resulted in poor forward visibility; and its high stall speed necessitated high-speed landings. On the other hand, it demonstrated excellent accuracy in firing tests, and in mock dogfights held in the summer of 1941 against a Bf 109 E-7 imported from Germany, the Ki-44's overall performance surpassed that of the Bf 109 E. Consequently, it was deemed a valuable asset capable of countering the latest Western fighters, though it remained unpopular among many veteran pilots who favored agile dogfighting capabilities.
According to FAOW #16 the attached photo features:
"the first prototype Nakajima Ki-44 "Shoki", serial number 4401, completed in August 1940. The photograph was taken in December of the same year at Tachikawa Airfield during operational testing, and the tail section of what appears to be the second prototype is visible on the far right of the frame. Due to the lack of a suitable high-powered engine, it was equipped with the Nakajima "Ha-41" (1,250 hp), a large-diameter bomber engine, resulting in an extremely wide nose. Only the first prototype differs from the second and subsequent prototypes in its cowling shape, cowl flaps, the air outlet immediately behind them, and exhaust pipes. The paint scheme is the Army's basic gray-green, and the stripe on the rear of the fuselage indicates that it is the first prototype."
In the "Army Aviation Weapons Research Policy" for the 1940 fiscal year, the "heavy" versus "light" fighter distinctions were explicitly codified. The "Heavy Fighter" evolved into the primary, all-purpose fighter—featuring high speed, heavy armament, superior range, and robust armor protection—capable of engaging both enemy fighters and bombers. Conversely, the "Light Fighter" was relegated to the role of an auxiliary fighter, prioritizing dogfighting but accepting compromises in performance and equipment to focus primarily on combat against other fighters.
In December 1941, Nakajima received a preliminary directive for the Ki-84 as an advanced iteration of the "Heavy Fighter"; this aircraft was later officially adopted as the Type 4 Fighter "Hayate". This aircraft emerged as the definitive, all-purpose fighter, excelling in speed, armament, armor protection, range, maneuverability, handling, and ease of production.
In the subsequent "Army Aviation Weapons Research Policy" for the 1943 fiscal year, the distinction between "light fighters" and "heavy fighters" was abolished; the "light fighter"—already an obsolete compromise—was absorbed into the "heavy fighter" category and redesignated as the "short-range fighter" (or "Kinsen"). That same policy introduced additional categories: "long-range fighter" ("Ensen"), "high-altitude fighter" ("Kohsen"), and "night fighter" ("Yasen").
P.S. This piece should teach a lesson to those who rely only on English sources, especially antiquated ones, and completely ignore the work of Japanese aviation historians!
No comments:
Post a Comment