The Zero Fighter and Mitsubishi Heavy Industries: Tracing the Giant of Japanese Aircraft Manufacturers

Nakajima, Mitsubishi, and Kawasaki were the undisputed pillars of Japan's three major aircraft manufacturers. These three companies focused not only on airplanes but also on the development of aircraft engines. In this article, we will focus on Mitsubishi Heavy Industries, widely known for the Zero fighter. By providing aircraft to both the Army and Navy and developing aircraft engines such as the "Kinsei" and "Kasei," Mitsubishi Heavy Industries made a significant contribution to military production as one of Japan's leading integrated heavy industrial companies.

1. Mitsubishi Heavy Industries and the Zero Fighter

The origins of Mitsubishi Heavy Industries date back to 1884. Mr. Yataro Iwasaki established the Nagasaki Shipyard and developed the shipbuilding business. Later, in 1934, it integrated its heavy machinery and railway vehicle divisions to become "Mitsubishi Heavy Industries, Ltd.," becoming one of Japan's representative integrated heavy industrial companies during the Pacific War.

The aircraft that immortalized its name was the Zero-sen (A6M) carrier-based fighter. In the early stages of the Pacific War, the Zero surprised the world with its unparalleled range and maneuverability. The design was led by Mr. Jiro Horikoshi, whose name became widely known through the film "The Wind Rises."

However, there is a surprising fact about the Zero. While the total production was approximately 10,423 units, only about 3,880 were manufactured by Mitsubishi, with the remaining 6,500-plus being produced under license by Nakajima Aircraft. In other words, the division of labor where "Mitsubishi designed the Zero, and Nakajima mass-produced it" was what supported Japan's air power. Moreover, there were differences in details depending on the manufacturer, resulting in subtle variations in paint color and spinner shape. Such episodes speak to the depth of the Zero's history.

2. The Genealogy of Mitsubishi Military Aircraft

Before the Zero, Mitsubishi had already produced innovative aircraft. The Type 96 Carrier-based Fighter (A5M), which appeared in 1936, was Japan's first all-metal monoplane fighter, and it was a step ahead in an era when biplane fighters were the mainstream. This design philosophy became the foundation for the Zero. Mr. Jiro Horikoshi also stated, "
The completion of the Type 96 Carrier-based Fighter was more deeply moving than that of the Zero."

When the Pacific War began, the Type 1 Land-based Attack Aircraft (G4M) became the main player for the Navy. It had an outstanding range and was active in vast theaters of war such as Guadalcanal and the Indian Ocean.

Furthermore, the Local Fighter Raiden (J2M) for homeland air defense, and the Reppu (A7M), which aimed to be the successor to the Zero, were also developed. The Reppu was scheduled to be equipped with the high-horsepower Ha-43 engine, but due to the worsening war situation and resource shortages, it never saw combat. Mitsubishi's technical team, led by Mr. Jiro Horikoshi, worked on developing the successor to the Zero, but it seems they faced considerable difficulties.

Mitsubishi also had a strong presence in aircraft for the Army. The Type 97 Heavy Bomber was active as the Army's main bomber from the Second Sino-Japanese War through the early stages of the Pacific War, and the Type 100 Command Reconnaissance Plane boasted such high-speed performance that it was praised by Allied pilots as a reconnaissance plane they could not catch.

Major self-developed military aircraft

Former Imperial Japanese Army
・Type 97 Heavy Bomber 2,064 aircraft (approx. 2,064, joint production with Nakajima)
・Type 97 Light Bomber 686–820 aircraft (Mitsubishi 636)
・Type 97 Command Reconnaissance Aircraft 437 aircraft
・Type 99 Assault/Army Reconnaissance Aircraft 2,385 aircraft (including army reconnaissance)
・ Type 100 Command Reconnaissance Aircraft 1,742 aircraft
・Type 4 Heavy Bomber "Hiryu" 635–697 aircraft *Successor to the Type 1 Attack Bomber for Mitsubishi
・Ki-83 Long-Range Fighter (Fastest fighter of the Imperial Japanese Army, 4 prototypes)

Former Imperial Japanese Navy
・Type 96 Carrier-based Fighter 1,094 aircraft
・Type 96 Land-based Attack Aircraft 421 aircraft (530 according to some sources)
・Type 97 No. 2 Carrier-based Attack Aircraft 205 aircraft *Another type of Type 97 Carrier Attack Bomber
・A6M Zero Carrier-based Fighter 10,430 aircraft (approx. 3,880 by Mitsubishi, the rest by Nakajima)
・Type 0 Observation Seaplane 532 aircraft
・Type 1 Land-based Attack Aircraft 2,435 aircraft
・Local Fighter "Raiden" 671 aircraft
・Type 17 Carrier-based Fighter "Reppu" 8 aircraft (prototypes only)
・Type 19 Local Fighter "Shusui" (Joint development by Army and Navy) 6 aircraft

3. Engine Development and Technical Challenges

Mitsubishi also pursued its own path in aircraft engines, the heart of the aircraft. Initially, they produced German BMW liquid-cooled engines under license, but eventually focused on air-cooled radial engines, developing series such as the "Kinsei," "Zuisei," and "Kasei." Among these, the highly reliable Kinsei series was installed in many aircraft.

Furthermore, toward the end of the war, they developed the 2,200-horsepower class Ha-43 with plans to install it in the Reppu and local fighters. If it had been mass-produced, it is believed that the performance of Japanese fighters would have improved significantly. Also, they were involved in the development of the first domestically produced jet engine, the "Ne-20," which was installed in the prototype jet aircraft "Kikka." Although mass production became a phantom due to the defeat, this experience contributed significantly to the reconstruction of the post-war aviation industry.

4. Rivalry with Nakajima

Indispensable to the history of Japanese aviation is the rivalry with Nakajima Aircraft Company. Nakajima leveraged its position as Japan's top production capacity and its wealth of development engineers to develop and mass-produce the main fighters for the Army and Navy. In particular, the Hayate is famous for being called the Greater East Asia Decisive Battle Aircraft along with Mitsubishi's Hiryu, and was considered a trump card at the end of the war. The two companies competed while also complementing each other, pushing up the overall level of Japanese aviation technology. The fact that Mitsubishi handled the design of the Zero and Nakajima took on the production is a symbolic episode of this.

5. Post-war Revival and Lessons

With the defeat, aircraft manufacturing was prohibited, and engineers were scattered. Mitsubishi was split up due to the dissolution of the zaibatsu, but was reintegrated in 1964 to become the new "Mitsubishi Heavy Industries, Ltd.." Afterward, they were involved in aircraft development again through the licensed production of the F-86 Sabre and the F-4 Phantom.

In the 1960s, they developed the domestic twin-turboprop aircraft MU-2, which achieved success in Western markets as well. It was one of the few postwar Japanese aircraft to achieve commercial success. Furthermore, in the 21st century, they took on the challenge of the domestic jet airliner MRJ (later SpaceJet). Although the project was ultimately canceled, the experience gained in composite materials and system integration became a significant asset for the Japanese aviation industry.

The phrase "Mitsubishi of the Zero Fighter" does not merely speak of past glory. It represents the very history of how engineers of that time unleashed their potential when facing adversity, and how they created new challenges from within that hardship.
For both companies and individuals, it is in times of trial that their true worth is tested. The journey of Mitsubishi conveys that universal lesson to the present day.