History of aicraft piston engines

T he curtiss company in the united states took up the

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Unformatted text preview: litary and small civilian aircraft T he advent of 4-cylinder vertical in-line, and later, opposed-cylinder, horizontal, air-cooled engines for light aircraft Liquid-Cooled Engines By 1920 the success of the Hispano-Suiza engines, then built in both the original and a larger (300 hp) size had convinced most designers that the w elded-cylinder construction was obsolescent. T he Curtiss Company in the United States took up the cast-aluminum engine, generally based on the Hispano-Suiza, with successive 12-cylinder designs known as the K -12, 13 C -12, D -12 (fig. 31), and V -1400 models. T hese were all of the 12-cylinder V-type, with 4 valves per cylinder, instead of 2 as in the Hispano-Suiza. The two early models had steel cylinder heads like that of the original Hispano-Suiza, but cooling was g reatly assisted by an integral stud, in the center between the valves, by m eans of which the head was held tightly against the water-jacket casting (fig. 34d). In the D-12 the steel head was abandoned, and the valve seats were bedded directly in the aluminum head, as in the Wright version of the H ispano-Suiza. T he great success of the Curtiss engines in racing (first to exceed 200 m ph in the M itchell 14 T rophy race, Detroit, 1922, and winner of the S chneider trophy in 1923 and 1925) led the Rolls-Royce company to d evelop aluminum V -12 engines of similar type. The first was the Kestrel 35 Figure 31.—Curtiss D-12 V-12 engine; 325 hp at 1800 rpm, 704 lb. This engine was the first to f ly more than 200 mph, in the Mitchell Trophy race, Detroit, 1922; and for the race, engine speed was increased so that it probably developed about 400 hp. (Photo A-3109) Figure 32.—Rolls-Royce M erlin 61 V-12 engine with 2-stage supercharger, about 1944; 2000 hp at 3000 rpm, about 1700 lb. (Photo A-3110) f ^ll]J&22* GLM INTERRUPTER G ermany's BREATHER BALANCED CRANKSHAFT Leading In-line Engine ROG_ER BEARING MAIN KARWGS MOUNTING TOR KtND S TATER Wyf®]2 [ | y K i^\m L \\\vT v l \ v\ii y •', V « ,.' \ i r //7\\\\ \ ' I \Y \ ky AUTCMAT£ALL> THROTTLE ; B pfte CVUNDG -=£: •.; SUPERCHARGER hr? P art-sectional drawing of the l iquid-cooled D .B.601N of 33.9 l itres, bore a nd s troke 1 50 x 160 m m . F eatures of the e ngine a re the t welve plunger in-line direct injection pump, a nd the fluid coupling which provides a n i nfinitely variable gear for t he supercharger drive. B.H.P. a t 2 ,600 r .p.m. i s 1 ,270, which for a w eight of 1,540 lb. = 1.20 I b./h.p. Figure 33.—Daimler-Benz, D B-601-N V-12, Germany's leading World War II engine (see also fig. 3 4h). Roller bearings are used on the crankpins. (From Flight, v ol. 4 1 , p. 367, April 16, 1942.) of 1927 soon followed by the r acing, or R, t ype which attained theretofore u nheard of p ower output in p roportion t o its size a nd w eight a nd won the S chneider trophy i n 1929 and 1931. The K estrel was followed b y the R olls-Royce Merlin (fig. 32), w inner of the B attle of B ritain, a nd also by t he Allison V -1710 (a fairly faithful copy of the M erlin), a nd the G erman D aimler-Benz (fig. 33) and J unkers V -12 liquid-cooled...
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