Performance of Twin-Duct Variable-Geometry Side Inlets at Mach Numbers of 1.5 to 2.0 Page: 4 of 33
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NACA RM E56K15 3
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2 diffuser static-pressure-variation survey, model station 48.91
3 compressor-face station, model station 64.97
APPARATUS AND PROCEDURE
A photograph and a -schematic diagram of the model are presented in
figures 1(a) and (b), respectively. The fuselage nose was drooped 40 with
respect to the fuselage centerline to aid pilot vision rather than to in-
fluence inlet performance. Because of armament storage, a rather sharp
bend was necessary in the ducts near model station 55 (fig. 1(b)) just
upstream of their junction.
The compression ramps of the inlets were raised above the fuselage
boundary layer; and a combination scoop and diverter, illustrated in fig-
ure 1(b), captured a portion of this boundary layer and diverted the re-
mainder. The flow of the captured boundary layer was controlled with
individual exit plugs and was exhausted at the base of the model. Main
diffuser airflow was also plug-controlled. The inlets were investigated
with the centerline of the initial portion of the duct alined with the
fuselage centerline (Oo-cant inlets) and also inclined downward 5 (-5s
cant inlets). For a part of the test the canard surfaces were mounted
low on the fuselage beneath the canopy as shown in figure 1(b).
Figures l(c) and (d) present a photograph and a schematic diagram, re-
spectively, of one of the inlets. The leading edge of the fixed-angle (90)
first ramp was positioned so that the first oblique shock was placed near
the cowl lip at a Mach number of 2.0. The position of the leading edge of
the second ramp was varied along the surface of the first. The unextended
position (e = 0, see fig. 1(d)) was such that, for a second-ramp angle of
19, the second oblique shock theoretically would be at the cowl lip at a
Mach number of 2.0. Several second-ramp angles were investigated, each
calculated to position the second oblique shock at the cowl lip for a
particular design Mach number with = 0. These were as follows:
Second-ramp Design Mach
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Yeager, Richard A.; Beheim, Milton A. & Klann, John L. Performance of Twin-Duct Variable-Geometry Side Inlets at Mach Numbers of 1.5 to 2.0, report, January 21, 1957; (https://digital.library.unt.edu/ark:/67531/metadc52996/m1/4/: accessed May 22, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.