An Investigation of the Effects of Sweep on the Characteristics of a High-Aspect-Ratio Wing in the Langley 8-Foot High-Speed Tunnel

An untwisted wing, which when unswept has an NACA 65-210 section, an aspect ratio of 9.0 and a taper ration of 2.5:1.0, has been tested with no sweep, and 30 deg and 45 deg of sweepback and sweepforward in conjunction with a typical fuselage at Mach numbers from 0.60 to 0.96 at angles of attack generally between -2 deg and 10 deg in the Langley 8-foot high-speed tunnel. Sweep was obtained by rotating the wing semispans about a point in the plane of symmetry. The normal-force, pitching-moment, profile-drag, and loading characteristics for the wings have been obtained from pressure measurements and wake surveys. The results indicate that the wings with +/-30 deg of sweep experienced the severe changes in characteristics associated with the presence of a shock at higher Mach numbers then did the wing without sweep. The differences between the Mach numbers at which the changes occurred for the wings with +/-30 deg sweep and no sweep were generally slightly less than the factor 1/cosDelta(sub r) times the Mach numbers at which the changes occurred for the unswept wing, Delta(sub r) being the sweep angle. The wings with +/-45 deg of sweep did not experience the changes in the characteristics associated with the presence of shock at an angle of attack of 2 deg at Mach numbers up to the highest test value. The magnitudes of changes in the normal-force and pitching-moment coefficients that occurred were less for the wing with 30 deg of sweep than for the unswept wing. The use of sweepforward was superior to sweepback in delaying and reducing the changes in the normal-force coefficients, but was inferior in delaying and reducing the changes in the profile-drag coefficients. Increasing the Mach number to the highest test values had little effect on the positions of the center of loads on the various configurations for the probable design load conditions.