The linearized subsonic flow about symmetrical nonlifting wing-body combinations

John B. Mcdevitt
naca-tn-3964
Apr 1957


Methods are presented for determining the linearized subsonic flow about symmetrical, nonlifting wing-body combinations. The wing is represented by a suitable planar distribution of elementary sources in accordance with the usual assumptions of linearized, thin-airfoil theory. The required boundary condition for tangential flow at the body surface is met by distributing along the body axis suitable distributions of three-dimensional sources and multipoles. As part of the present analysis, a theory is presented for determining the flow about circular or noncircular bodies by the use of axially distributed sources and multipoles. The flow over thin, nonlifting airfoils having symmetrical profiles is also studied in considerable detail, and it is shown that the concept of the oblique source filament can be used in obtaining numerical results for wings having tapered as well as untapered plan forms. A comparison of theory and experiment is made for two 45 degree sweptback wings in combination with basic Sears-Haack bodies of revolution and in combination with the basic bodies indented according to Whitcomb's transonic area rule. The effect of indenting the body on the pressure distribution near the wing-body juncture is of particular interest for sweptwing and body combinations. The effect of the area-rule indentation was to adjust the pressure field near the body so that the wing surface isobars tended to follow the local sweep lines of the wing.

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