NACA-RM-A50I14

Abstract

INTRODUCTION <br>The merits of large amounts of sweep for efficient flight (i.e., for Reasonably high lift-drag ratios) at moderate supersonic speeds have been demonstrated by wind-tunnel tests of a wing with the leading edge swept back 63&#176; (references 1 and 2). At low subsonic Mach numbers this wing is characterized by large variations of longitudinal stability with angle of attack even at low lift coefficients (references 3 and 4). These stability variations were attributed in reference 3 to spanwise flow in the boundary layer and to flow separation at wing sections near the tip. Twisting and cambering the wing a moderate amount to relieve the lead at the tip and to obtain a more uniform distribution of load at a moderately low lift coefficient (0.25 at a Mach number of: 1.5) resulted in higher lift-drag ratios at supersonic speeds (reference 5) but provided little improvement of the stability characteristics a$ subsonic speeds (reference 6). Tests of a wing twisted and cambered for uniform load at a moderately high lift coefficient (0.5 at a Mach number of 1.4) likewise showed no improvement of the stability characteristics at low subsonic Mach numbers (reference 7). <br>In reference 7, the poor stability characteristics of the wing at comparatively low lift coefficients were attributed to the inability of the wing sections near the tip to maintain lift flow separation to sufficiently high angles of attack. <br>Subsequent to the tests of reference 7 it was reasoned that the lift range for satisfactory stability characteristics might be extended to higher lift coefficients by increasing the range of usable lift of the sections near the tip through an increase of the thickness of these sections . Computations showed that the increase of drag at supersonic speeds due to the increased thickness of sections near the tip would be relatively Small. <br>Consequently, the model used for the research reported in reference 7 was altered to incorporated thicker sections from the midsemispan to the tip. For expediency in model construction, the twist of the revised portion of the wing was also modified from that :of the original wing. <br>Tests of. the wing were made in one of the Ames 7-by 10-foot wind tunnels. The longitudinal characteristics of this wing as shown by force and pressure-distribution measurements are presented herein. Also included are the effects of a fuselage, of upper-surface fences, of spoilers, of elevens, and of a leading-edge flap on the low-speed characteristics of the wing.