The Nakajima Homare (誉, "praise" or, more usually, "honour") was an air-cooled twin-row 18 cylinder

radial Radial is a geometric term of location which may refer to: Mathematics and Direction * Vector (geometric), a line * Radius, adjective form of * Radial distance, a directional coordinate in a polar coordinate system * Radial set * A bearing f ...

Japanese Japanese may refer to: * Something from or related to Japan, an island country in East Asia * Japanese language, spoken mainly in Japan * Japanese people, the ethnic group that identifies with Japan through ancestry or culture ** Japanese diaspor ...

aircraft engine manufactured during

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

. Producing almost 2,000 horsepower, it was used widely by both the

Imperial Japanese Army The was the official ground-based armed force of the Empire of Japan from 1868 to 1945. It was controlled by the Imperial Japanese Army General Staff Office and the Ministry of the Army, both of which were nominally subordinate to the Emperor o ...

and the

Imperial Japanese Navy The Imperial Japanese Navy (IJN; Kyūjitai: Shinjitai: ' 'Navy of the Greater Japanese Empire', or ''Nippon Kaigun'', 'Japanese Navy') was the navy of the Empire of Japan from 1868 to 1945, when it was dissolved following Japan's surrender ...

. Given the Navy service designation NK9, the "Homare" was also given the company designation NBA, Army experimental designation Ha-45 (ハ45) or, Army long designation Nakajima Army Type 4 1,900 hp Air-Cooled Radial and, (coincidentally) unified designation code of Ha-45.Gunston 1989, p.105.

Design and development

Development of the Homare started in 1940, and certification was completed in 1941. It succeeded Nakajima's previous 14 cylinder Sakae (Ha-25) engine, which had its own forward seven cylinders staggered from the rear seven for efficient cooling. The design was exceptionally compact, with an external diameter of 118 cm, a mere 3 cm larger than the Sakae. With a bore and stroke of 130 mm x 150 mm, it was classified as a short-stroke engine. It was designed to output around 1800 hp (1340 kW), or 100 hp (75 kW) per cylinder. However, the tight design of the engine made it difficult to maintain quality in manufacturing, and unreliability in the field was a significant problem; actual output of early models at altitude was in the range of 1300 hp (970 kW), far below the designed capability. Later models had improved performance, and it became one of the predominant powerplants of Japanese military aircraft in the latter part of the war. A total of 9089 were produced.

Variants

* Homare 11 - 1,650 hp (1,230 kW), 1,820 hp (1,357 kW), 1,900 hp (1,417 kW) * Homare 12 - 1,825 hp (1,361 kW) * Homare 21 - 1,990 hp (1,460 kW) * Homare 23 - 2,000 hp (1,491 kW) * Homare 25 - 2,000 hp (1,491 kW) * Homare 42 - 2,200 hp (1,640 kW)

Applications

* Aichi B7A *

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Nakajima Ki-84 The is a single-seat fighter flown by the Imperial Japanese Army Air Service in the last two years of World War II. The Allied reporting name was "Frank"; the Japanese Army designation was . The Ki-84 is generally considered the best Japanese ...

* Yokosuka D4Y5 *

Yokosuka P1Y1 The Yokosuka P1Y ''Ginga'' (銀河, "Galaxy") was a twin-engine, land-based bomber developed for the Japanese Imperial Navy in World War II. It was the successor to the Mitsubishi G4M and given the Allied reporting name "Frances". Design and d ...

Specifications (Ha-45-21)

References

Notes

Bibliography

* * ''Jane's Fighting Aircraft of World War II''. London. Studio Editions Ltd, 1998. * Gunston, Bill. ''World Encyclopaedia of Aero Engines''. Cambridge, England. Patrick Stephens Limited, 1989. {{Imperial Japanese Navy aero engines Aircraft air-cooled radial piston engines 1940s aircraft piston engines Nakajima aircraft engines