Comparison of Three Exit-Area Control Devices on an N.A.C.A. Cowling, Special Report Page: 4 of 12
[11] p. : ill.View a full description of this report.
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3
The electric motor used to drive the propeller devel-
ops 15 horsepower at 1,150 rpm. It was mounted inside the
wing, and the propeller was driven through an extension
shaft.
Each cowling arrangement was tested at several dif-
ferent values of the cowling-exit area. For convenience,
the test conditions are tabulated as follows.Type of exit-
area controlControllable
cowling flaps
Variable-
length cowl-
ing skirt
Bottom opening
with adjust-
able flapRatio of exit
Cowling-exit Exit area area to nacelle
condition (sq in.) cross-sectional
areaFlap angle (deg
0
10
20
30
Exit gap (in.):
0.25
.78
1.50
Flap angle (d.e15.9
42.0
65.6
94.0
15.9
49.0
94.00.049
.130
.203
.291
.049
.152
.2910 26,7 .082
9 1 .097
20 39.2 .121
30 46.0 .142
40 52.9 .164
50 60.9 .189One test was made with the propeller removed, the
exit sealed, and with a large nose fairing added to the
nacelle (fig. 2) to establish a basis for computing the
net efficiency.
RESULTS AND DISCUSSION
All data are redued to standard nondimensional coef-
ficients. The symbols and coefficients involved are de-
fined as follows:In-e --C33C t I- I-~- -- ---~u ,~ ~-r~-L r~re I- -~-kr r~ --- -~r~ ,-~ rc~r I--~I-LCLI~-
):
):4
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McHugh, James G. Comparison of Three Exit-Area Control Devices on an N.A.C.A. Cowling, Special Report, report, May 1940; (https://digital.library.unt.edu/ark:/67531/metadc65123/m1/4/: accessed April 19, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.