NACA-RM-L55J06

Abstract

INTRODUCTION <br>Results of tests to determine the effect of spanwise location of the sweep discontinuity of M- and W-wings on the static longitudinal and lateral stability characteristics of a complete model are presented in references 1 and 2, respectively. The results show that these wings (especially the&#160;M type) provide favorable longitudinal stability characteristics and good directional stability at high lift. Little advantage in stability appeared to result from locating the sweep discontinuity of M-wings outboard of the 40-percent-semispan location; and since, from divergence-speed considerations for a given ratio of torsional stiffness to bending stiffness, it is desirable to keep the sweptforward panels of an M-wing relatively small (ref. 3), the M-wing with its sweep discontinuity at 40- percent semispan was selected for further study. <br>During the tests of reference 1, it was noted that the flow above the sweptforward panel was directed toward the fuselage at positive angles of attack and that separation at the wing root occurred at low angles of attack. It was reasoned that flow separation at the wing root might be delayed somewhat by mounting the wing with .its upper surface tangent to the top of the fuselage, rather than having the chord plane of the wing located on the fuselage center line. The present investigation therefore was intended to determine any possible advantages of raising the wing height and, in, addition, to extend the range of tail height covered in references 1 and 2 to include a horizontal tail mounted at the top of the vertical tail (T-tail). <br>The M-wing tested had an aspect ratio of 6, a taper ratio of 0.60, NACA 67A009 airfoil sections parallel to the plane of symmetry, and &#177;470 sweep of the quarter-chord line. The data presented herein were obtained' from tests in the Langley 300 MPH 7- by 10-foot wind tunnel.