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Aviation History
1942
1942 - 1495.PDF
JULY I6TH, 1942 FLIGHT 7* JAPAN'S POWER UNITS (Right) A longitudinal sec tion of the " Kinsei " engine (Below) Sectional sketch of the cylinder of Type 90 engine. (Marine Works, Nakajima Aircraft Works and Aichi Tokei-Denki, Ltd.). (6) In-line engine, water-cooled, B-M.W. VI (from 1925 to 1937) (Kawasaki shipyards, now Kawasaki Aircraft Works, Ltd.). (7) Radial engine, 9-cylinder, air-cooled, 460 h.p. Bristol Jupiter IV and VI (Nakajima Aircraft Works). (8) In-line engine, water-cooled Junkers (Mitsubishi Com bustion Engines, Ltd., now Mitsubishi Aircraft Engine Works). (9) In-line engine, water-cooled, 90 deg. V-type 300 h.p. 8-cylinder, 60 deg., and a V- engine 450 and 600 h.p. 12-cylinder, French Hispano-Suiza (Mitsubishi Air craft Engine Works). About the original Japanese develop ment one can say the following: — Approximately from 1925 an engine designated Type 14 of 550 h.p. and of domestic design was in production by the Naval Works at Hiro. It was-a 12-cylinder broad-arrow type, similar to the Lorraine which was produced in the same works. But the construction of the Type 14 was thoroughly original. It was a super-dimensional engine, niich in 1928 reached an output of 750 h.p. and was pro duced for a twin-engine metal flying boat of the type 89, constructed in the same works. From 1927 and onwards original designs of the local civilian aircraft industry came gradually into appearance. Of these, three engine types were most successful: the Tokio-Gasdenki Company (now Hichi) produced an air- cooled 7-cylinder radial "Kamikaze" (Divine Wind) of 130 h.p. and a 9-cylinder radial of 300 h.p. designated "Amakaze" (Heavenly Wind). These firms are also known as the producers of a small engine for training air craft, the performance of which gradually rose from 150 to 350 h.p. These engines are still in employment. A Jap Design The Hiro Marine Works produced to the design of Saneyoshi, an engineer who studied in Germany, a new Type 90 engine. The maximum performance of this engine was 1,100 h.p., and was then in the class of the most power ful types. The engine was of eighteen cylinders in a 40 deg. broad-arrow arrangement, and water-cooled. The engine was characterised by a small frontal area. The following data will provide a closer study of this type: Bore 145 mm., stroke 160 mm., stroke capacity 47.5 V*ftres, dry weight 720 kg. Interesting details are shown in the adjoining sketch. In the left half of the sketch, showing the liquid-cooled design, the wet steel cylinder liners are screwed into the light alloy cylinder head block, which is cast integrally with the coolant jacket. At the lower end a shouldered sleeve nut, screwing on the liner, stresses the jacket por tion of the block in compression. The combustion pres sure is 1 transferred from the cylinder head to the upper end of the liner, and further by the shoulder of the sleeve nut to the jacket flange by which the block is attached to the crankcase. For this reason it was possible to reduce the section of the jacket wall. As the attachment flange of the block is not stressed in tension, the required strength is obtained with a small expenditure of material. The water-jacket seal is effected in the usual way by means of a rubber ring. Externally, the liner is protected against corrosion by chromium plating. Water-cooling of the cylinder, and especially of the exhaust valves, has proved to be success ful. Even with fuel of the quality available at that time jl it was possible to obtain a consumption of 200 g. /h.p. Interesting experiments were subsequently made with semi-air-cooled cylinders on the same engine. The right- hand section of the sketch shows this arrange ment. The shape of the cylinder head was suit ably adapted, whilst the cylin der liners were furnished with cooling fins. The cooling of this part was effected by normal air flow induced in flight, and not by any special fan. With this type of cylinder, fuel consumption was equal to that of the liquid-cooled version ; the spacing of cylinders was considerably reduced, and consequently the weight and length of the engine cut down.* A comparison of the semi- liquid-cooled engine with the fully liquid-cooled version shows considerable simplification. The required liquid quantity is considerably reduced, and the dimensions of the radiator are reduced by approximately 50 per cent. Because of its low fuel consumption and high reliability, the Type 90 engine was widely used for a twin-engine fly ing boat and a twin-engine bomber, both for long-range employment. The engine was later improved by a super charger, and reached a performance of 1,500 h.p. at a weight of 750 kg. This power output, however, was too high for aircraft produced at that time. A smaller version of the Type 90 was an engine of 12 cylinders, broad-arrow arrangement. This type had a bore of 135 mm. and a stroke capacity of 27.5 litres. It appeared first in 1931 under the designation of Type 91, and had a rated power of 600 h.p. and a maximum power * This is difficult to understand as the semi-air-coole' I example has a coolant belt around the combustion area of thf- cylinder which is necessarily of the same diameter as on the liquid-cooled version.
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