naca-rm-l50g17a
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National Advisory Committee for Aeronautics, Research Memorandum - Transonic Flight Tests to Compare the Zero-Lift Drag of Underslung and Symmetrical Nacelles Varied Chordwise at 40% Semispan of 45° Sweptback, Tapered Wing
Rocket-powered models were flown at transonic speeds to determine
the effect of nacelle location on the zero-lift drag. Nacelles of fine-
ness.ratio 9.66 were mounted in underslung_and symmetrical‘(midwing)
positions along the wing chord at no percent of the semispan. The noses
of the nacelles were located at four chordwise stations equivalent to
0.35, 0.50, 0.76, and 1.20 wing chords ahead of the wing leading edge
at ho percent wing semispan. The wing had a sweepback angle of #50 along
the quarter—chord line, an aspect ratio of 6.0, a taper ratio equal
to 0.6, and an NACA 65A009 airfoil section in the free—stream direction.
The fuselage fineness ratio was 10.0.
Results from flight tests showed that no unfavorable interference
effects were evident for either underslung or symmetrical nacelle posi-
tions at Mach numbers between 0.80 and 0.93. At a Mach number of 1.0
large unfavorable interference effects were present and caused the "
experimental nacelle drag coefficients to be from 85 percent to 285 per—'
cent higher than the value estimated for the nacelle without interferenCe.
Nacelles mounted symmetrically on the wing generally had lower drag coef-
ficients than nacelles located.in underslung positions at Mach numbers
from 0.95 to 1.20. The symmetrically mounted nacelles located in rear
positions at the 35- and 50-percent—chord positions gave the lOWest drag,
and the underslung location at the 76-percent—chord location had the
highest drag. The addition of nacelles to the wings of the models,
independent of their chordwise location at #0 percent of the semispan,
reduced the Mach number at which the transonic drag rise of the total
configuration occurred by 0.03 to 0.07.
As part of a general transonic research program of the National
Advisory Committee for Aeronautics to determine the aerodynamic proper-
ties of promising configurations, rocket—propelled models were tested
in free flight to determine the variations of. ..zero—lift drag coefficient
for a medium—size bomber configuration with nacelles in_various posi-
tions on the wings.
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naca-rm-l50g17a Transonic Flight Tests to Compare the Zero-Lift Drag of Underslung and Symmetrical Nacelles Varied Chordwise at 40% Semispan of 45° Sweptback, Tapered Wing.pdf | Download |
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