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
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
CRANKSHAFT Leading In-line Engine ROG_ER BEARING
MAIN KARWGS MOUNTING TOR
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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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This document was uploaded on 01/19/2014.
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