History of aicraft piston engines

This engine figs 20 and 21 t able 2 p 90 was a

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Unformatted text preview: rman's No. Ill b iplane. R otary types had been built for automobiles by Stephen Balzer and A damsFarwell in the United States before the turn of the century, and this type h ad been originally planned and built for the Langley Aerodrome, but it was first adapted to flying in the Gnome. This engine (figs. 20 and 21, t able 2, p. 90) was a masterpiece for its time and deserves special attention h ere. T he design of the Gnome was by Laurent Seguin. Made entirely from steel forgings machined all over, with integrally machined cooling fins a nd a modern master-rod system, it anticipated many features of the latest large air-cooled radials. The rotary feature was used in order to e liminate the flywheel, which had been previously thought essential, and also to assist in cooling. It frequently used a cowling with central air intake, s omething like that later developed for static radials by the National Advisory Committee for Aeronautics (see p. 9 0). U nlike the NACA cowling, however, the cowling used here had its opening for outlet air at the bottom, r ather than around the rear edge. Its primary purpose was, probably, to 22 Figure 19.—Anzani 3-cylinder fan-type engine, 1909. The type used in Bleriot's crossing of the English Channel, its rating was 24.5 hp at 1600 rpm, 145 lb. (Photo A-49846-E) e ncourage discharge of exhaust gases and oil under t he airplane, away from t he pilot. The fact that it also greatly reduced engine "drag" as compared w ith uncowled engines, may not have been understood at that time. This seven-cylinder model, and subsequent larger and more powerful versions, b ecame perhaps the most popular aircraft engines up to World War I a nd were used widely by both sides through that war. I h ad the pleasure of flying with a Gnome engine in 1920 a nd found it exceptionally free of vibration and also relatively quiet. 6 T he only d isagreeable feature was the castor-oil fumes discharged from the exhaust. L ubrication was achieved by pumping castor oil into the crankshaft at a 23 Figure 20.—Gnome 7-cylinder Monosoupape rotary-radial engine, 1910; 50 hp at 1150 rpm, 165 lb. In this longitudinal section note inlet valve in piston to admit fuel-air mixture from crankcase. (From Aerosphere 1939, p. 341) 24 21.—Gnome 50-hp 7-cylinder engine, 1910, as installed in er Canard pusher biplane. A -50895) fixed r ate, a nd oil which was not burned eventually found its way out of t he exhaust ports and, despite the cowling, much of it settled on the a irplane (and on the pilot!). One of my first assignments in aviation (1917) was to make tests to show that mineral oil could be used in aero engines. Previous to that time castor oil had been considered as indispensable for a ero engines as it was for young children. A nother interesting feature of the Gnome engine was its method of c ontrol. No carburetor was used; the fuel and air were introduced through t he hollow crankshaft, by means of separate valves controlled by the pilot. Because of the great iner...
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This document was uploaded on 01/19/2014.

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