Some measurements of aerodynamic forces and moments at subsonic speeds on a rectangular wing of aspect ratio 2 oscillating about the midchord

Abstract : Some measurements were made of the aerodynamic forces and moments acting on a rectangular wing of aspect ratio 2 which was oscillated about the midchord. These measurements were made at four frequencies (31, 43, 54, and 62 cps) over a range of Mach number from 0.15 to 0.81, a range of reduced frequency from 0.15 to 1.32, and a range of Reynolds number from 0.60 x 10 to the sixth power to 9.21 x 10 to the 6th power. It was feasible to compare results of a portion of these measurements with some published experimental data and, in general, reasonable agreement was found to exist. An appendix is included to show the correction of the root reaction for inertia and aerodynamic effects in order to determine the total aerodynamic load. Comparison of the measured aerodynamic forces and moments with those predicted by the method of Reissner and by the method of Lawrence and Gerber for wings of aspect ratio 2 in incompressible flow showed generally good agreement. Comparison of the measured quantities with those predicted by two-dimensional-flow theory indicated that the effects of finiteness of span on the aerodynamic forces and moments are considerable. Some experimental results pertaining to the influence of wind-tunnel-wall effects on nonsteady aerodynamic measurement have been included.