Experimental Poststall Rotary Aerodynamic Coefficients for Airplane-like Configurations

Abstract

Military and civilian airplane losses caused by out-of-contro l spin motions are significant. Knowledge of rotary coefficients is necessary to understand the cause of spin entry and to devise proper recovery techniques. An exploratory wind-tunnel investigation has been conducted at Ames Research Center on simple airplane-like configurations on a rotary sting apparatus at rotation rates up to 10 rps. Rotary coefficients have been measured at unit Reynolds numbers from 2xl06nT1 to 24.6xl06nT1 and at angles of attack from 45° to 90°. Results show that the aerodynamic characteristics at steady spin rates are highly dependent on both spin rate and Reynolds number. Nomenclature A = body reference area, ird2/4 b = wing span, 0.457 m (1.5 ft) CD = body drag force per unit length/qd c'N = body normal force per unit length/qd CR = moment about spin axis/qSb, positive clockwise (viewed from rear) c'y = body side force per unit length/qd Cy = body side force/qA d = diameter of center body, 0.0762 m (0.25 ft) £ = length of nose section M = freestream Mach number Nj = tangent ogive nose, see Fig. 4 q = freestream dynamic pressure Rd = Reynolds number based on d S -wing reference area, 0.0491 m2 (0.5234 ft2) TI = aft body, circular cylinder tail section, see Fig. 4 T2 = T] plus tail surfaces, see Fig. 4 U = freestream velocity W = wing, see Fig. 4 xn = distances, see Fig. 9 a.f = local angle of attack, see Fig. 9 Of = angle between the freestream velocity vector and the body x axis \l/ = angle of roll about the body x axis co = angular velocity of the rotary sting Q = reduced spin rate, ub/2U