Nakajima Kotobuki

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Nakajima Hikōki

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Kotobuki
Production period: 1930 – unknown
Manufacturer: Nakajima Hikōki
Developing country: JapanJapan Japan
First run: 1930
Working principle: Otto
Motor design: Radial engine
Cylinder: 9
Drilling: 146 mm
Hub: 160 mm
Displacement: 24,100 cm 3
Mixture preparation: Carburetor
Engine charging: no
Cooling system: Air cooling
Power: 405-570 kW
Dimensions: 350 kg
Previous model: none
Successor: Hikari

The Nakajima Ha-1 Kotobuki ( Japanese寿, dt. "Longevity") was an aircraft engine from the Japanese manufacturer Nakajima Hikōki . The radial engine was built under license by the British engine Bristol Jupiter

development and construction

In 1917, Chikuhei Nakajima founded an aircraft construction company in Ojima (now Ōta ) in Gunma Prefecture . The first aircraft - the Nakajima Type 1 - was built in 1918. The machine was powered by a US engine. In 1920 the company sent Kimihei Nakajima to France to research European advances in aircraft construction, and in 1922 it began manufacturing its own engines in a new factory in Tokyo . Were built engines based on the air-cooled two-cylinder piston engine Lawrance A-3 .

Bristol Jupiter VII on display in the Shuttleworth Collection

At that time, the Lawrance engine was a rarity, as most contemporary air-cooled engines were rotary engines whose cylinders rotated together with the propeller . Kimihei, however, heard of a conventional reciprocating engine with good cooling capacity that was being developed in England at the time . He noticed the British Gloster Gamecock fighter with its Bristol-Jupiter engine , the design of which was ahead of its time. The engine had tappets with automatic valve clearance compensation , spiral tubes for even intake distribution and four valves per cylinder. In 1925 he received a building license for Jupiter. After a visit by two engineers from the Bristol Aircraft Company , production of the Jupiter types 6 with a nominal output of 420  hp (309  kW ) and 7 with 450 hp (331 kW) and Supercharger began at Nakajima in 1927.

Pratt & Whitney Wasp

After evaluating the nine-cylinder star engine series Pratt & Whitney Wasp , Nakajima tried to combine the advantages of Jupiter with the rational construction of the Wasp. Nakajima built a number of individual pieces with the designations AA, AB, AC and AD for technical research purposes. The subsequent design with the designation AE was ultimately promising with a bore of 160 millimeters and a piston stroke of 170 millimeters.

Prototypes were built and function tested , but the design was initially abandoned due to the complex structure. Nakajima continued to experiment with different cylinder designs. Finally, in 1929, the AH design was completed with a bore of 146 millimeters, a stroke of 160 millimeters and a displacement of 24.1 liters. This model was the final version of the development.

In June 1930 the first prototype was finished and passed the endurance tests for approval. Flight tests were then carried out with a Nakajima A2N . In December 1931 the engine was accepted by the Imperial Japanese Navy for the Nakajima C3N under the designation Ha-1 Ko. With this, Nakajima had developed the first Japanese air-cooled nine-cylinder engine. The engine was given the name Kotobuki because of its connection to Jupiter.

The Kotobuki was further developed into the Hikari with a bore of 160 millimeters, a stroke of 180 millimeters, a displacement of 32.6 liters and a rated output of 720 hp (530 kW), which was used in the aircraft types Nakajima A4N and Yokosuka B4Y .

In order to increase the performance further, the basic construction was finally expanded to fourteen cylinders in two rows and built under the designation Nakajima Ha-5 .

Versions

2-quay-1
Nominal output 585  PS (430  kW )
2-quay-3
Nominal output 610 hp (449 kW)
3-quay
Rated output 710 hp (522 kW)

use

See also

Individual evidence

  1. ↑ a b c d e Engine development at Nakajima 1923 - 1945. Classic Airplane Museum, accessed on March 24, 2020 (English).
  2. ^ Bill Gunston: World Encyclopedia of Aero Engines . Patrick Stephens, Cambridge 1989, ISBN 1-85260-163-9 , pp. 104 (English).