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Aviation History
1920
1920 - 0123.PDF
JANUARY 29, 1920 " Flight" Copyright A 200 h.p. Breguet rotary with variable compression :This engine was built under licence, the originators being Damblanc-Mutti. Louis Breguet. In addition to his aeroplanes and seaplane, M. Breguet exhibited an engine unit developing some 800 h.p. This consists of two Breguet-Bugatti engines, placed end to end, but one slightly higher than the other. The Bugatti engine, it will be remembered, consists of two vertical 8-cylinder units, placed side by side on a common crank case. In the Breguet- Bugatti combination this arrangement is made use of to accommodate the propeller shaft, which runs through the space between the cylinders of the lower engine. A series of auto- matic clutches are provided, which ensure that in the case of a breakdown of one engine, this is automatically thrown out of gear, and the only effect of the breakdown is that one-fourth less power is transmitted to the main airscrew shaft. The arrangement, although probably doing all that is claimed for it, looks very complicated and somewhat heavy, but for airship work it might find its use. Compared with other engines of the same, or even greater power, of which several types were shown, the Breguet-Bugatti would appear to be unnecessarily complicated. On the Breguet stand was shown also a rotary engine of 200 h.p., about which it was said that it had variable compres- sion, but as the engine was built under licence, the originators being apparently Damblanc-Mutti, no particulars were available as to how this variation is brought about. In external appearance the engine looks very much like any other rotary, the only unusual feature one noticed being the method of springing the valves. This was accomplished by auxiliary rockers, placed under the main ones, operated by coil springs passing down along the outside of the cylinders to eyebolts on the circumference of the crank case. In the case of the exhaust valves the object was evidently to get the springs- away from the hot gases, but in the case of the inlet valves, it is less obvious what were the advantages of this arrangement, except possibly the question of accessibility. Clerget, Blin et Cie. The exhibits of this firm were somewhat in the nature of a series of " milestones," the engines shown ranging from the earlier days of the firm down to the latest engines designed. Thus one saw on this stand a specimen of the 60 h.p. 7-cylinder type 7Y of 1912, the 80-h.p. 7-cylinder type 7Z of IQ13. the 130 h.p. 9 cylinder type 9B of 1916, the 200 h.p. 11-cylinder type 11 EB of 1917. Of the latter type a sectioned model was also shown. This type, it may be remembered, had the induction pipes on the front (propeller) end of the engine. Of modern types only two were exhibited. Of these one was a type 9J 9-cylinder rotary of no h.p. Although maintaining its general family resemblance to previous Clerget engines, the type f>J shows various minor modifications. Thus the induc- " Flight" Copyright The Clerget 9-cylinder, type 9J, rated at 110 h.p. tion pipes issue from the crank case behind the space between adjoining cylinders, and have a pronounced lateral bend at the top, where they are joined by means of two flanges. Also, instead of the elliptical section formerly characteristic of Clerget engines, the 9 J has induction pipes' of circular section. The bore and stroke of the 9J is 105 mm. and 140 mm. respectively, and the weight of the engine is 115 kg. (about 253 lbs. or 23 lbs. per h.p.). The only other engine of new type exhibited was a small " Flight" Copyright. A CLERGET RADIAL : This small stationary engine, the type 2K, is rated at 16 h.p. and drives an airscrew of 3 ft. 6 ins. diameter. two-cylinder radial, known as the type 2K, rated at 16 h.p. This small engine is fitted with an airscrew of 3 ft. 6 ins. diameter only, and is a very pretty little job, although one does not think that the power will be quite sufficient, even for a very small machine after the style of the de Marcay " Passe- partout." The bore and stroke is 85 mm. and 100 mm. respectively. The weight is stated to be 22 kg. (48 -4 lbs., or just over 3 lbs. per h.p.). If made slightly larger, so as to develop about 20 h.p., there should be quite a market for such a small light engine, as in that case a very useful machine could be built, having the necessary reserve of power for climbing, etc., but when only 16 h.p. is available, it will mean that the engine has to run all out continuously, and there will be little or no reserve when the power begins to drop off. (To be continued.) 123
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