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The High Speed Aerodynamic Effects of Modifications to the Wing and Wing Fuselage Intersection of an Airplane Model with the Wing Swept Back 35°

Wind—tunnel tests at high subsonic Mach numbers were conducted
on a model of a pursuit airplane having a 359 swept—back wing.
Tests were made to determine the effect of (l) the wing trailing—
edge angle, (2) the fuselage contour at the wing—fuselage inter—
section, and (3) an extension at the leading edge of the wing root.

The results indicate that decreasing the wing trailing—edge
angle eliminated (at least up to 0.90 Lhch number) the reversal of
pitching-moment and aileron hinge-moment characteristics noted. at
high Mach numbers for small angles of attack and aileron defle'd—é-
tions with the true—contour wing. Contouring the fuselage side to
the estimated. shape of the undisturbed. streamlines over the swept—
‘back wing reduced the interference at the wing-fuselage inter-—
section and improved the high-speed characteristics of the model.
No benefits were derived from. the wing leading—edge extension.
Comparatively large angles of sweepback of wings and central
surfaces are incorporated in the design of many current airplanes
in order to delay the onset of compressibility effects. Since
experimental data for highly swept lifting surfaces are rather
incomplete, a series of wind—tunnel tests were conducted with a
sergispan model of a pursuit airplane having the wing swept back
35.

During the tests several modifications were made to the wing
and wing—fuselage intersection of the model, primarily to eliminate
the reversal of pitching—moment and aileron hinge-moment charac—
teristics noted for small angles of attack and aileron deflections
at high Mach numbers, and to increase the divergence Inch number of
the model to a value more closely approximating that predicted by
simple theory. This report presents the results of that portion of
the tests dealing with the modificatiOns to the model. Subsequent
reports will present theremainder of the data.