The Nakajima Ha1 Kotobuki (寿, "Longevity") was an aero-engine developed by Nakajima. It was a radial piston developed under licence from the

Bristol Jupiter The Bristol Jupiter was a British nine-cylinder single-row piston radial engine built by the Bristol Aeroplane Company. Originally designed late in World War I and known as the Cosmos Jupiter, a lengthy series of upgrades and developments turn ...

Design and development

In 1917, Chikuhei Nakajima set up the "Airplane Institute" at Ojima Town in

Gunma Prefecture is a prefecture of Japan located in the Kantō region of Honshu. Gunma Prefecture has a population of 1,937,626 (1 October 2019) and has a geographic area of 6,362 km2 (2,456 sq mi). Gunma Prefecture borders Niigata Prefecture and Fukushima ...

. In 1918 they built their first airplane; the "Nakajima Type 1" with a U.S.A. made engine.Engine development at Nakajima 1923 - 1945 In 1920 the company sent Kimihei Nakajima to France to study European advances, and in 1922 started their own engine factory in Tokyo. This led to production of engines based on the

Lawrance A-3 The Lawrance A-3 or Lawrance Model A was an American twin-cylinder aircraft piston engine. Designed by Charles Lawrance in the mid-1910s the engine was produced by the Lawrance Aero Engine Company and under license by Excelsior. Weighing 200&nbs ...

two-cylinder air-cooled horizontally opposed engine. BristolJupiter

At the time the Lawrence was an oddity. Most air-cooled engines at that time were

rotary engine The rotary engine is an early type of internal combustion engine, usually designed with an odd number of cylinders per row in a radial configuration. The engine's crankshaft remained stationary in operation, while the entire crankcase and i ...

s using cylinders that rotated together with the

propeller A propeller (colloquially often called a screw if on a ship or an airscrew if on an aircraft) is a device with a rotating hub and radiating blades that are set at a pitch to form a helical spiral which, when rotated, exerts linear thrust upon ...

, but Kimihei overheard that an engine with good cooling capability with fixed cylinders was being developed in England. He observed the English

Gloster Gamecock The Gloster Gamecock was a biplane fighter designed and produced by the British aircraft manufacturer Gloster. The Gamecock was a development of the earlier Grebe Mk III, an early interwar fighter procured by the Royal Air Force (RAF). Wor ...

fighter with its

engine, which was an advanced design for the era with an automatic adjustment device for

tappet A tappet is most commonly a component in an internal combustion engine which converts the rotating motion of the camshaft into linear motion of the valves, either directly or indirectly. An earlier use of the term was for part of the valve gear ...

clearance, spiral piping for even intake distribution, and a four-valve intake and exhaust system. He acquired a manufacturing license for the Jupiter in 1925.Gunston 1989, p.104. In 1927, after inviting two production engineer instructors from the Bristol company, the Jupiter Type 6 of 420 PS and Type 7 of 450 PS with a supercharger were put into production at the Nakajima factory. Pratt and Whitney Wasp

After studying the

Pratt & Whitney Wasp The Pratt & Whitney Wasp was the civilian name of a family of air-cooled radial piston engines developed in the 1930s, 1940s, and 1950s.Gunston 1989, p.114. The Pratt & Whitney Aircraft Company (P&W) was founded in 1925 by Frederick B. Rentsch ...

9-cylinder radial, Nakajima tried to combine the good points found in Jupiter design with the

rational Rationality is the quality of being guided by or based on reasons. In this regard, a person acts rationally if they have a good reason for what they do or a belief is rational if it is based on strong evidence. This quality can apply to an abili ...

design of the Wasp. Nakajima then produced a series of engine types, named "AA", "AB", "AC", and "AD", as engineering exercises. The next engine design, the "AE", was innovative, with a bore of 160 mm and a stroke of 170 mm.

Prototypes A prototype is an early sample, model, or release of a product built to test a concept or process. It is a term used in a variety of contexts, including semantics, design, electronics, and software programming. A prototype is generally used to ...

were made and performance tests were done, but this engine was not adopted due to its very complex engineering. Nakajima continued testing different cylinder designs. In 1929, the "AH" design, with bore and stroke of 146 × 160 mm and a total displacement of 24.1 L, was completed. This was to be the final version of this basic engine design. In June 1930 the first prototype of was completed and it passed the durability test for the type approval in the summer. Then flight tests were started using a

Nakajima A2N The Nakajima A2N or Navy Type 90 Carrier Fighter was a Japanese carrier-borne fighter of the 1930s. It was a single-engined biplane of mixed construction, with a fixed tailwheel undercarriage. Design and development The A2N was originally dev ...

carrier plane. Nakajima had designed the first Japanese originally designed air-cooled 9-cylinder engine, the 450 PS "Kotobuki". In December 1931, this engine was approved and adopted by the Navy as the Ha-1 Ko for the Type 97 carrier fighter. The engine was named, in connection with the Jupiter engine, "Kotobuki". The "Kotobuki" engine was improved and developed into the "

Hikari may refer to: Places *Hikari Station, a station on Sanyō Main Line in Hikari, Yamaguchi * Hikari, Chiba, a former town in Sousa District, Chiba, Japan *Hikari, Yamaguchi, a city in Yamaguchi Prefecture, Japan People *Hikari (name), people and ...

(light)" engine with the bore and stroke expanded to the limit of the cylinder (160 × 180 mm for a displacement of 32.6 L), with the power was increased to 720 PS. The "Hikari" was used in Type 95 carrier fighters and Type 96 Carrier Attack Plane. In search of more power the basic design was extended into a 14-cylinder 2-row engine, the " Ha-5 Ha-41 Ha-109" series.

Variants

;2-Kai-1: ;2-Kai-3: ;3-Kai: ;Ha1 :;Ha1a :;Ha1b

Applications

Mitsubishi A5M The Mitsubishi A5M, formal Japanese Navy designation , experimental Navy designation Mitsubishi Navy Experimental 9-''Shi'' Carrier Fighter, company designation Mitsubishi ''Ka''-14, was a Japanese carrier-based fighter aircraft. It was the worl ...

Mitsubishi Ki-18 The was an unsuccessful and unsolicited attempt by Mitsubishi to meet a 1934 requirement issued by the Japanese Army for a modern single-seat monoplane fighter suitable to the needs of the Imperial Japanese Army Air Force. During this competiti ...

* Nakajima A1N2 *

Nakajima Ki-8 The was an unsuccessful attempt by the Nakajima Aircraft Company to interest the Imperial Japanese Army Air Force in a two-seat modern monoplane fighter. Design & Development Development of the Ki-8, (a.k.a. Nakajima DF), began in 1933, based ...

Nakajima Ki-27 The was the main fighter aircraft used by the Imperial Japanese Army Air Service up until 1940. Its Allied nickname was "Nate", although it was called "Abdul" in the "China Burma India" (CBI) theater by many post war sources; Allied Intelligen ...

Nakajima E4N The Nakajima E4N was a Japanese shipboard reconnaissance aircraft of the 1930s. It was a two-seat, single-engine, equal-span biplane seaplane used primarily by the Imperial Japanese Navy. Development The first prototype of the Type 90-2 Reconna ...

Nakajima E8N The Nakajima E8N was a Japanese ship-borne, catapult-launched, reconnaissance seaplane of the Second Sino-Japanese War. It was a single-engine, two-seat biplane with a central main-float and underwing outriggers. During the Pacific War, it was ...

Nakajima Ki-34 The Nakajima Ki-34 was a Japanese light transport of World War II. It was a twin-engine, low-wing monoplane; the undercarriage was of tailwheel type with retractable main units. During the Pacific War, the Allies assigned the type the reporting ...

Nakajima Type 91 The Nakajima Army Type 91 Fighter was a Japanese fighter of the 1930s. It was a single-engine, single-seat parasol monoplane with a fixed, tailwheel undercarriage. Development Designed in response to an Army requirement of 1927, the Type 91 w ...

Specifications

References

Bibliography