This preview shows page 1. Sign up to view the full content.
Unformatted text preview: Rateau, and
e xperimental models were tested during the war, but none was put into
service use. Laboratory work on gear-driven superchargers was conducted
d uring the war by the RAF at Farnborough, England. Intensive development of supercharging equipment began both in England and the United
S tates in 1918. R.-R. MERLIN "SIXTY-ONE" H V ERTICAL
FINS ™ P ASSAGES INLET BRANCH
O F INTERCOOLER B OOST
U NIT Perspective drawing of the new two-stage
two-speed supercharger of the Rolls-Royce
Merlin 61 engine. The twin rotors are
m ounted on a single shaft. Change of
speed of the supercharger drive is effected
by a hydraulic pump. FULL GEAR
C LUTCH & CEAR
DRIVE T WO-SPEED
R EDUCING VALVE Figure 64.—A two-stage two-speed geared supercharger with intercooler and aftercooler, as installed
on the Rolls-Royce Merlin 61 engine of 1942, the first of its kind to be used in service. (From Flight,
vol. 4 2, p. 656, Dec. 17, 1942) 68 M any types of compressors have been considered, but only one,
t he centrifugal type, ever got beyond the experimental stage. The Royal
Aircraft Factory had Armstrong-Siddeley construct a radial engine with
a b uilt-in geared centrifugal supercharger in 1916, but the design was
unsuccessful, probably because of torsional vibration in the drive system.
Siddeley did not produce a successful geared supercharger until that used
in 1926 in the Jaguar (see fig. 38).
G eared superchargers were built experimentally by Curtiss and by
W right Aeronautical Corporation in 1925, b ut the first United States production engine to be so equipped was the Pratt & Whitney Wasp of 1927,
a y ear later than the Jaguar. After 1930 all military and transport engines
w ere equipped with geared centrifugal superchargers, and in all cases some
kind of flexible coupling was introduced in the gear train to prevent
c ritical torsional vibration. The culmination of the geared centrifugal type
is represented by the 2-stage, 2-speed supercharger of the Rolls-Royce
M erlin (fig. 64).
I n 1918 t he Engineering Division of the Army Air Service contracted
w ith the General Electric Company to develop turbo-superchargers of the
R ateau type. The man in charge of this development for GE was Dr.
Sanford A. Moss, who remained in this position for over twenty years.
E xperimental models applied to the Liberty engine were tested at the
t op of Pikes Peak in 1918, and in flight at McCook Field in 1919.
F igure 65 shows an installation of this early type of General Electric
s upercharger on a Liberty engine. A Le Pere airplane with this equipment
h eld the world's altitude record for the years 1920, 1921, and 1922. S upercharging was hard on an engine not originally designed for it, and I remember when Major Schroeder, who made the 1920 record, returned
from a flight with the Liberty engine and its nacelle cut in two by a failed
c onnecting rod at the third crank from the front end. The only elements
h olding the four forward cylinders an...
View Full Document
- Winter '14
- The Land