History of aicraft piston engines

T he o x 5 a w ater cooled v 8 had an aluminum

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Unformatted text preview: rtance or success of the Gnome and its descendants. As the rotary engines became obsolete, the water-cooled V-type e ngine became dominant. In the United States the Curtiss O X - 5 e ngine (fig. 22 and table 1, p. 88) led the field until 1917, w hen the Liberty and H ispano-Suiza engines were introduced. T he O X - 5 , a w ater-cooled V-8, had an aluminum crankcase, castiron cylinders (see fig. 34a) with sheet m onel-metal w ater jackets brazed o nto the barrels, and overhead valves, push-rod operated. Used by both A rmy and Navy, it powered practically all United States and Canadian t raining airplanes and was probably responsible for training more pilots for World War I than any other engine. The best-known trainer, the Curtiss J N - 4 , affectionately known as the Jenny, is shown in figure 23. M y first airplane ride (1917) was in a single-float seaplane with the O X X - 2 , t he Navy version of this engine.7 27 Figure 22.—Curtiss OX-5 water-cooled V-8 engine (NASM 1920-8), 1917; 90 hp at 1400 rpm, 320 lb (see also fig. 34a). (Photo A-1832) Figure 23.—Curtiss J N-4 Jenny airplane with OX-5 engine, 1915. (Photo courtesy Harrah's Automotive Museum, Reno, Nevada) F igure 2 4.—Mercedes 6 -cylinder engine, 1 9 1 5 ; 180 hp at 1500 r p m , 618 lb. This engine pioneered w elded-steel c ylinder c o n s t r u c t i o n . (From [ B r i t i s h ] Ministry of Munitions, Report on the 180-H.P. Mercedes Engine, M arch 1918) F igure 2 5.—Rolls-Royce E agle V - 1 2 engine, 1 9 1 7 ; 3 6 0 hp at 1800 r p m , 9 0 0 lb. Its cylinder c onstruction is similar to t h a t of the Mercedes in figure 2 4 . (Photo A-487) T he O X - 5 engine was considered very reliable for its day, but few pilots completed the training course (very short) without at least one forced landing. Its weaknesses included single ignition, a rather flimsy v alve-operating gear including "pull-rods" for the inlet valves, and a t endency to leak water from the water pump down onto the low-slung c arburetor. In freezing weather the latter defect accounted for many forced landings A v ery important new style in liquid-cooled cylinder design appeared in 1915 on the German 6-cylinder 180-hp M ercedes engine (fig. 24 and t able 1, p. 88). This was the built-up welded-steel cylinder construction widely used for a long time thereafter in most water-cooled engines. It was copied by such famous makes as the Rolls-Royce Eagle (fig. 25), Liberty, F IAT (Fabrica Italiana Automobili Torino), Renault, Salmson, and B MW (Bayerische Motoren Werke), but finally gave way to the castaluminum en bloc construction, to be discussed later (p. 33). A mong the engines built in this style, an important one was the United S tates Liberty (figs. 26, 27, and 34b), which was developed under extraordinary circumstances. 8 After a decision on 29 May 1917 (only 7 weeks after the United States entered the war), by the War Production Board t o build an airplane engine more powerful than any in use up to that t ime, J . G. Vincent, Chief Engineer of Packard, and Elbert J. Hall, of the H all-Scott Motor Co., started to design such an engine in the Willard H otel, Washington, D . O On 31 M ay prelim...
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This document was uploaded on 01/19/2014.

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