The Mitsubishi A5M, formal Japanese Navy designation , experimental Navy designation Mitsubishi Navy Experimental 9-Shi Carrier Fighter, company designation Mitsubishi Ka-14, was a WWII-era Japanese carrier-based fighter aircraft. The Type number is from the last two digits of the Japanese imperial year 2596 (1936) when it entered service with the Imperial Navy.
It was the world's first low-wing monoplane shipboard fighter to enter service and the predecessor to the famous Mitsubishi A6M "Zero". The Allied reporting name was Claude.
Design and development
In 1934, the Imperial Japanese Navy prepared a specification for an advanced fighter, requiring a maximum speed of at and able to climb to in 6.5 minutes. This 9-shi (1934) specification produced designs from both Mitsubishi and Nakajima.
Mitsubishi assigned the task of designing the new fighter to a team led by Jiro Horikoshi (original creator of the similar but unsuccessful Mitsubishi 1MF10, and later responsible for the famous A6M Zero). The resulting design, designated Ka-14 by Mitsubishi, was an all-metal low-wing fighter, with a thin elliptical inverted gull wing and a fixed undercarriage, which was chosen as the increase in performance (estimated as 10% in drag, but only a mere 3% increase in maximum speed) arising from use of a retractable undercarriage was not felt to justify the extra weight. The first prototype, powered by a 447 kW (600 hp) Nakajima Kotobuki 5 radial engine, flew on 4 February 1935. The aircraft far exceeded the requirements of the specification, with a maximum speed of being reached. The second prototype was fitted with a revised, ungulled wing, and after various changes to maximize maneuverability and reduce drag, was ordered into production as the A5M.
With the Ka-14 demonstrating excellent performance, the Imperial Japanese Army Air Force ordered a single modified prototype for evaluation as the Ki-18. While this demonstrated similar performance to the Navy aircraft and hence was far faster than the IJAAF's current fighter, the Kawasaki Ki-10 biplane, the type was rejected by the army owing to its reduced maneuverability. The Army then produced a specification for an improved advanced fighter to replace the Ki-10. Mitsubishi, busy turning the Ka-14 into the A5M, submitted a minimally changed aircraft as the Ki-33, this being defeated by Nakajima's competing aircraft, which was ordered into service as the Ki-27.
Operational history
The aircraft entered service in early 1937, and soon saw action in aerial battles at the start of the Second Sino-Japanese War, including air-to-air battles with the Republic of China Air Force's Boeing P-26C Model 281 "Peashooters" in the world's first aerial dogfighting and kills between monoplane fighters built of mostly metal.
Chinese Nationalist pilots, primarily flying the Curtiss Hawk III, fought against the Japanese, but the A5M was the better of almost every fighter aircraft it encountered. Though armed with only a pair of machine-guns, the new fighter proved effective and damage-tolerant, with excellent manoeuvrability and robust construction. Later on A5M's also provided much-needed escorts for the then-modern but vulnerable Mitsubishi G3M bombers.
The Mitsubishi team continued to improve the A5M, working through versions until the final A5M4, which carried an external underside drop tank to provide fuel for extended range.
The A5M's most competitive adversary in the air was the Polikarpov I-16, a fast and heavily armed fighter flown by both Chinese Air Force regulars and Soviet volunteers. Air battles in 1938, especially on 18 February and 29 April, ranked among the largest air battles ever fought at the time. The battle of 29 April saw 67 Polikarpov fighters (31 I-16s and 36 I-15 bis) against 18 G3Ms escorted by 27 A5Ms. Each side claimed victory: the Chinese/Soviet side claimed 21 Japanese aircraft (11 fighters and 10 bombers) shot down with 50 Japanese airmen killed and two captured having bailed out while losing 12 aircraft and 5 pilots killed; the Japanese claimed they lost only two G3Ms and two A5Ms shot down with over 40 Chinese aircraft shot down.
104 A5M aircraft were modified to accommodate a two-seater cockpit. This version, used for pilot training, was dubbed the A5M4-K. K version aircraft continued to be used for pilot training long after standard A5Ms left front-line service.
Almost all A5Ms had open cockpits. A closed cockpit was tried but found little favor among Navy aviators. All had fixed, non-retractable undercarriage. Wheel spats were a feature of standard fighters but not training aircraft.