Nomenclature C D = drag coefficient, D/qS C pmax = maximum pressure coefficient C L = lift coefficient, L/qS C La = lift curve slope at a = 0°, per deg d = wing leading edge diameter, in. (Fig. la) d/l = wing thickness ratio D = drag,Ib I = wing length, in. (Fig. la) L = lift, Ib L/D = lift-drag ratio, C L /C D Ma> = freestream Mach number q = dynamic pressure, psi r = leading edge radius, in. S = wing planform area, in. 2 a = angle of attack, deg A = sweep angle, deg (Fig. la) 7= ratio of specific heats T HIS paper is a brief resume of the preliminary results obtained from an investigation recently conducted at a Mach number of 20 in helium flow to determine the effects of leading edge blunting and sweep angle on the static longitudinal stability characteristics of basic delta planforms, with particular emphasis on maximum lift-drag ratio. For the purpose of brevity, only summary plots are presented.The experimental results were obtained in the Langley 22-in. helium tunnel utilizing a contoured nozzle to obtain a uniform freestream Mach number of 20.3. 1 Stagnation temperature for the tests was approximately 80°F. Reynolds number, based on chord length, ranged from 1.5 X 10 6 to 5.5 X 10 6 , but for wings having thickness ratios less than 0.034, a constant Reynolds number of 3.7 X 10 6 was maintained in order to minimize any possible Reynolds number \ * \ 1 ----
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