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Unformatted text preview: p engine used cast-iron L-head cylinders. It was
t he forerunner of contemporary horizontal-opposed light-plane engines.
L ater models use composite aluminum and steel cylinders similar to the
J - 5 cylinder of figure 36e. Engines of this type built by Continental Motors
C orporation and by others, including principally the Lycoming Division
of Avco Corporation, have developed to a remarkable degree of reliability
a nd performance. In 1961, a license to build Continental engines of this
t ype was acquired by Rolls-Royce, a real compliment to the high quality
of these small powerplants.
A nother interesting category of air-cooled engines comprises those
b uilt for installation in model airplanes. These are usually 1-cylinder 2-cycle
engines of less than 1-in. b ore and stroke (fig. 49). Some are rated up to 1
h p at speeds of 15,000 rpm or more. Originating in the United States about
1930, these engines were produced in very large quantities between 1945
a nd 1950. I t is claimed that there were 180 manufacturers of model engines
in the United States during that period, and their total production, in
n umber of engines, p robably exceeded that of all other aircraft engines
c ombined. The popularity of engine-powered model airplanes fell off about
50 F igure 4 8.—Continental A - 4 0 air-cooled horizontalopposed 4-cylinder engine, 1 9 3 1 ; 40 hp at 2 5 0 0 r p m ,
1 45 lb. This engine was the f o r e r u n n e r of contemporary
light-plane engines. (Photo
F igure 4 9.—Model a irplane
S uper Cyclone (NASM 1 9 4 4 - 2 0 ) , about
1 9 5 0 ; a bout 1/10 hp at 10,000 r p m , 5
o unces. This typical single-cylinder, 2cycle, a ir-cooled model engine uses
s pecial fuel with hot-wire ignition.
A-36625) F igure 5 0.—Frontal c oolant radiator for Liberty engine on
1 9 1 9 - 5 1 ) , 1918. This position
f or the radiator required a
l arge cooling surface and c ont r i b u t e d heavily to airplane
d rag. (Photo
A-9850-D). F igure
e xposed Lawrance J - l
e ngine on Curtiss F 4-C1, a bout
1 924. Below, P artially exposed
W right J-5 engine on Ryan NYP
a irplane Spirit
( NASM 1928-21), after return
f rom Europe, 1927.
A-47190.A-1193-B). F igure 5 2.—Radial e ngine with
N ACA-type cowling on Frank
H awks' L ockheed Air Express,
A-33428-E) 1950, b ut has revived during the past decade. During 1966 one manufacturer
a lone produced a million model aero engines. Air Versus Liquid Cooling
T he classic and often emotionally charged argument over the relative
m erits of liquid and air cooling started with the early days of flying
( Antoinette vs. Gnome, for example) and persisted to the end of World
W ar II, when the advent of jets and turbo props diverted attention elsewhere.
As we have seen, water cooling was dominant through World War I,
e xcept for the rotaries, which at its close were obsolescent. European
m ilitary aviation remained generally committed to water cooling up to and
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This document was uploaded on 01/19/2014.
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