Supersonic wave drag of nonlifting sweptback tapered wings with Mach lines behind the line of maximum thickness

Abstract : A theoretical investigation of the supersonic wave drag of nonlifting sweptback tapered wings having thin symmetrical double-wedge airfoil sections with maximum thickness at 50 percent chord has been presented in NACA TN No. 1448. The present paper extends the investigation to include supersonic maximum-thickness edges; that is, the flight velocity component normal to the line of maximum thickness is supersonic. This condition exists at Mach numbers for which the Mach lines have angles of sweep greater than that of the line of maximum thickness. For wings of equal root bending stress (and hence of different aspect ratio) and given sweepback, taper increases the wing wave-drag coefficient at Mach numbers for which the maximum-thickness line is moderately supersonic and has negligible effect at higher Mach numbers. This trend is similar to that evidence by the effect of high aspect ratio for given sweepback and taper ratio. Comparisons on the basis of constant aspect ratio for given sweepback, however, indicate a decrease of the drag coefficient with taper at Mach numbers corresponding to moderately supersonic maximum-thickness lines and a negligible effect due to taper at the higher Mach numbers. For given taper ratio and aspect ratio, increased sweepback increases the drag coefficient at Mach numbers for which the maximum-thickness line is supersonic.