The effect on zero-lift drag of an indented fuselage or a thickened wing-root modification to a 45 degrees sweptback wing-body configuration as determined by flight tests at transonic speeds Page: 4 of 22
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NACA RM L51FI5
As part of a general transonic research program of the National
Advisory Committee for Aeronautics to determine the aerodynamic properties
of promising configurations, rocket-propelled models were tested in free
flight to determine the effect on zero-lift drag of two exploratory wing-
body-juncture modifications of a transonic airplane configuration. Some
wing-plus-interference drag coefficients were also determined.
Much theoretical and experimental work has been directed toward the
modification of the fuselage shape in the vicinity of the wing root in
an attempt to delay the drag-rise Mach number of the configuration
(references 1 and 2). This type of fuselage modification, however, has
not been investigated at transonic or supersonic speeds. The present
investigation is designed to explore the possibilities of reducing wing-
body interference throughout the transonic region.
At present, the most effective method of delaying the drag rise and
reducing the transonic wing-body drag is to use thin sweptback wings.
The structural problems of designing and building very thin swept wings
to withstand the loads encountered in transonic flight, however, are
considerable. A possible recourse would be a wing with thin outboard
sections and thicker root sections. The structural benefits gained by
a thickened wing root must be balanced against the possible adverse
effects on the drag coefficient. Experimental results in reference 3
for nacelles mounted near the wing root showed favorable low drag which
led to the hope that thickness could be added near the wing root without
undue penalty. The modified wing root was designed to explore this
Drag coefficients of the configurations tested are presented over
a continuous Mach number range of 0.8 to 1.25. The corresponding
Reynolds number range was from 3.3 x 106 to 7.1 x 106 when it was based
on the mean aerodynamic chord of the wing.
b wing span
CDT total drag coefficient, based on SW
CD wing-plus-interference drag coefficient, based on SW
M Mach number
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Pepper, William B. The effect on zero-lift drag of an indented fuselage or a thickened wing-root modification to a 45 degrees sweptback wing-body configuration as determined by flight tests at transonic speeds, report, September 20, 1951; (digital.library.unt.edu/ark:/67531/metadc58898/m1/4/: accessed December 13, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.