The importance of the A-5M carrier-based fighter for the development of Japanese industry and military potential in the mid-1930s cannot be overestimated. The creation of this aircraft meant the end of Japan's dependence on imports of European military equipment and opened up for the country the possibility of building its own carrier-based aircraft, whose aircraft in all respects - speed, armament and maneuverability - could be compared with the best Western models.

The first of six prototypes of this aircraft took off in February 1935, and the A-5M1 aircraft began to enter service in the spring of 1937. The total production of this type of aircraft was 980 aircraft in modifications from A-5M1 to A-5M4, the latter had an open cockpit instead of a closed one. In addition, 103 two-seat training aircraft A-5M4-K were manufactured. In general, the Japanese naval aviation was armed with more than 1000 such machines, they were withdrawn from the first line units only in 1943.

They practically did not participate in hostilities.

^* Usually, instead of a 50-kilogram bomb, a suspended fuel tank of 60 liters of fuel was suspended under the fuselage of the same weight.

Fighter First flight: 1935 Mitsubishi

In the new fighter competition organized by the Imperial Army in 1934, Mitsubishi initially did not participate, while Nakajima presented a low-wing fixed landing gear (later designated Ki-11), which looked like a Boeing P-26. The Kawasaki company entered the competition with a polutoraplan fighter, which became known as the Ki-10. The Ki-11 was slightly faster than the Ki-10, but the Kawasaki was more manoeuvrable. However, the Imperial Army adopted, though without much enthusiasm, the Kawasaki aircraft under the designation "type 95 fighter".

At the same time, the fighter, created by Mitsubishi according to the specifications of the Imperial Navy 9-si, showed outstanding performance and not only earned respect from the fleet, but also from the army. With the consent of the Navy, the Army ordered a copy of the 9-C specification fighter (subsequently A5M1, Allied code name Claude) for evaluation.

Instead of naval aircraft, designated Ki-18, it was supposed to have army equipment and systems. The differences from the naval model were in the direction of the throttle (the army vehicles had a direct lever stroke for the idle mode), the installation of standard army machine guns, a new longer engine hood, and the rudder area was increased to improve handling. To prevent the car from burrowing into the dust and dirt of the by no means concrete airfields of China and Manchuria, wheels of increased diameter with appropriate fairings were also installed. The reverse throttle movement probably resulted from French influence. Armament traditionally consisted of two rifle-caliber machine guns.

The production of the aircraft was completed in August 1935, after which, until the spring of 1936, the machine was tested at the Aviation Research Institute in Tachikawa and at the Akeno Army Flight School. At the suggestion of Akeno Flight School instructor Captain Ujiro Matsumura (Capt Oujiro Matsumura) in early 1936, the Kotobuki 5 engine was replaced by the Kotobuki 3. The Kotobuki 3 gearless engine proved to be the army's preference. During flight tests, conducted mainly by Captain Matsumara, a speed of 444 km / h was reached at an altitude of 3050 meters. At maximum speed, the height of 5000 meters was reached in 6 minutes 25.8 seconds. Tests of the Ki-18 continued until the fighter was badly damaged during a forced landing.

From the point of view of pilots flying the Ki-18, the aircraft lacked stability and controllability, but no changes were made. However, during tests at the Akeno flight school, the Ki-18 received excellent marks in all respects and it was proposed to put this model into mass production. These recommendations from the Akeno flight school were countered by an aerotechnical research institute's dissatisfaction with the engine, which was described as unreliable. Supporting the claims of an older organization, the Army Air Staff decided that the characteristics of the Ki-18 were insufficient to accept this aircraft into service. Thus, it was decided to hold a new competition, in which three aircraft manufacturing companies were invited to participate.

The history of the Ki-18 ended after the production of one aircraft and the expression of dissatisfaction on the part of the army air headquarters. This caused surprise in the Mitsubishi company, since the Imperial Navy recognized this aircraft as revolutionary. With a high degree of probability, we can say that the endless rivalry and jealousy between the army and navy led to the rejection of the Ki-18. Nevertheless, this machine shook the "ground" confidence that "a good fighter should have two wings", and it was on the basis of the Ki-18 test results that the requirements for a promising fighter were formulated.

Photo	Description
	Drawing Ki-18 Fighter
	Fighter Ki-18

Fighter First flight: 1936 Mitsubishi

To save time, it was decided not to build Ki-33 prototypes from scratch, but to modernize two production A5M2a fighters.

Changes were made only in the installation of a more powerful Nakajima Ha-1-Ko engine with a power of 745 hp, which took the place of an earlier version of the same engine - Nakajima Kotobuki 2 KAI 3b with a power of 690 hp, which was installed on the A5M2a. The replacement was not difficult, due to the identical dimensions of the engines, which were just different versions of the licensed English Bristol "Jupiter".

Also on the Ki-33, the area of the vertical tail was slightly increased to improve longitudinal stability, and the shape of the rear cockpit garrot was also slightly changed, the contours of which became more straight instead of the curved profile on the A5M2a.

A closed cockpit canopy was used. Moreover, the sliding part of it opened by moving forward. Minor internal modifications were also carried out, similar to those previously carried out on the Ki-18 version, replacing naval instruments and weapons with army ones and adapting naval control systems to army standards.

The upgrades were completed in the early summer of 1936, and both Ki-33 prototypes were delivered to the Army Aviation Technical Research Institute in Kagamigahara (Kagamigahara Rikugun Kokogijutsi Kenkyujo), where comparative tests were carried out with competitors from Kawasaki and Nakajima.

Comparative tests took place from November 1936 to the spring of 1937. Overall, the results of all three competitors were very close, with the Ki-33 being faster than the Ki-27, but slightly inferior to Kawasaki's Ki-28. In addition, the Ki-33 inherited from the naval prototype the longest flight range (fuel tank capacity was 326 liters) and the largest ammunition load for machine guns - 800 rounds per barrel. However, the Ki-33 showed an unsatisfactory rate of climb and was significantly inferior to both competitors in horizontal maneuver, which decided the results of the competition not in its favor. As a result, the army rejected the Ki-33, opting for Nakajima's machine, which became the main army fighter for the next five years.

Ki-33 prototypes were used for some time at the company as flying laboratories, but after 1938 their trace was lost.

Photo	Description
	Drawing Ki-33

Bibliography

• Japanese Aircraft 1910-1941/Putnam. Robert C. Mikesh, Shorzoe Abe/
• Japanese aircraft of World War II. /Oleg Doroshkekvich/
• An experienced Mitsubishi Ki-18 fighter. Japan /Alternative History/
• Encyclopedia of military equipment /Aerospace Publishing/