The was a two-row, 14-cylinder air-cooled radial engine built by the

Mitsubishi Aircraft Company Mitsubishi Aircraft CompanyGunston p. 318 (''Mitsubishi Kokuki'') was the new name given by the Mitsubishi Company (''Mitsubishi Shokai''), in 1928, to its subsidiary, Mitsubishi Internal Combustion (''Mitsubishi Nainenki''), to reflect its chang ...

for the

Imperial Japanese Army Air Service The Imperial Japanese Army Air Service (IJAAS) or Imperial Japanese Army Air Force (IJAAF; ja, 大日本帝國陸軍航空部隊, Dainippon Teikoku Rikugun Kōkūbutai, lit=Greater Japan Empire Army Air Corps) was the aviation force of the Im ...

(IJAAS) and the

Imperial Japanese Navy Air Service The was the Naval aviation, air arm of the Imperial Japanese Navy (IJN). The organization was responsible for the operation of naval aircraft and the conduct of aerial warfare in the Pacific War. The Japanese military acquired their first air ...

(IJNAS) in the early 1930s. Like many aircraft engines in Japan, there were multiple designations for this engine. The company model designation was A6(7) while it was an experimental engine project. Once accepted, it was known as the "Shinten" or MK1 by the IJNAS, and Ha6 by the IJAAS.Francillon, René J. Japanese Aircraft of the Pacific War. p. 515

Design and development

The Mitsubishi Shinten was a development of the early

Mitsubishi Kinsei The was a 14-cylinder, air-cooled, twin-row radial aircraft engine developed by Mitsubishi Heavy Industries in Japan in 1934 for the Imperial Japanese Navy. The Mitsubishi model designation for this engine was A8 while it was an experimental p ...

(A4) engine. The

stroke A stroke is a medical condition in which poor blood flow to the brain causes cell death. There are two main types of stroke: ischemic, due to lack of blood flow, and hemorrhagic, due to bleeding. Both cause parts of the brain to stop functionin ...

of the Kinsei was increased from to on the Shinten model 11 and to on the Shinten model 21 and 21Kai designs. Lengthening the stroke increased the

displacement Displacement may refer to: Physical sciences Mathematics and Physics *Displacement (geometry), is the difference between the final and initial position of a point trajectory (for instance, the center of mass of a moving object). The actual path ...

from the Kinsei's to for the Shinten model 11. The increased displacement raised the horsepower from to at take-off power. Initially the Ha6 was to be installed on the IJAAS

Mitsubishi Ki-21 The (Allied reporting name: "Sally" /"Gwen") was a Japanese heavy bomber during World War II. It began operations during the Second Sino-Japanese War participating in the Nomonhan Incident, and in the first stages of the Pacific War, including ...

bomber aircraft, but it was decided to use a competing engine, the

Nakajima Ha5 The Nakajima Ha5 is a twin row, 14 cylinder air-cooled radial aircraft engine built by the Japanese Nakajima Aircraft Company. The engine was a development of earlier single-row Japanese engines, the Kotobuki and Hikari, which had combined fe ...

instead. Furthermore, Mitsubishi was ordered to produce Nakajima's engine at its factory under license. So only 113 Shinten/Ha6 engines were made and they were installed on only few types of aircraft. In order to beat the rival and also to develop a more powerful engine for the new Navy Attack Bomber that became the infamous

Mitsubishi G6M The Mitsubishi G4M was a twin-engine, land-based medium bomber formerly manufactured by the Mitsubishi Aircraft Company, a part of Mitsubishi Heavy Industries, and operated by the Imperial Japanese Navy from 1940 to 1945. Its official designat ...

Betty, the Shinten was developed into the

Mitsubishi Kasei The was a two-row, 14-cylinder air-cooled radial engine built by Mitsubishi Heavy Industries and used in a variety of World War II Japanese aircraft, such as Mitsubishi J2M and Mitsubishi G4M.Gunston 1989, p.104. The Mitsubishi model designa ...

by increasing the bore from to which in turn brought the displacement to and increased power to .

IJNAS engine naming method

It was the Imperial Japanese Navy's common practice to refer to its engines by name. The Japanese method of identifying model numbers of aircraft engines is unique in that the model number always has two digits and may be followed by one or more letters. The first digit represents the major version of the engine and the second number represents the minor version of that model engine. The first model number assigned to an engine is always 11, meaning the first major design and first minor version of that design. A major change to the design increments the first number and resets the second number to one. A minor change to the engine model increments the second number by one. If a very minor change is made, suffix letters are added after the model number. When a special modification is made, the model number is followed by the suffix 'kai', as in the Shinten Model 21kai, which decodes as the second model of the Shinten engine, 1st revision, specially modified.

IJAAS engine naming method

The Imperial Japanese Army Air Service referred to its engines by their engine (Japanese:Hatsudoki abbreviated Ha) model number. Ha numbers were assigned in sequence as the engine design was accepted. This engine (Ha6) would be the 6th engine accepted by the IJAAS.

Variants

; Shinten 11 (A7) : 920 hp at 2300 rpm (take-off), 700 hp at 2100 rpm (normal). 1934 4 made ; Shinten 21 (A6) : 950 hp at 2320 rpm (take-off), 800 hp at 2150 rpm (normal). ; Shinten 21kai (A6) : 1200 hp at 2360 rpm (take-off), 1020 hp at 2250 rpm (normal). 1934–1939 109 made

Applications

Yokosuka H5Y The Yokosuka H5Y (short designation) or Yokosuka Navy Type 99 Flying Boat Model 11 (九九式飛行艇, ''99shiki hikōtei'') (long designation), given the allied code name Cherry, was an IJNAS flying boat in service from 1938. Design and develo ...

Specifications (Shinten)

References

Notes

Bibliography

* Matsuoka Hisamitsu, Nakanishi Masayoshi. The History of Mitsubishi Aero Engines 1915–1945. Miki Press, Japan, 2005. * * * {{Imperial Japanese Navy aero engines 1930s aircraft piston engines Aircraft air-cooled radial piston engines Shinten