Wing sweep and blunting effects on delta planforms at m equal 20

Abstract

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 ----

Thin flat balances for testing thin delta wings at hypersonic speeds

“…As expected, the wing plus body generates negative C N at zero angle of attack. The balance used by Witcofski and Marcum [8] was not sensitive enough to measure this difference. Although the body will come into the aerodynamic shadow at α = 6.5 • , it can be seen from figure 13 that, even at α = 12 • , the normal force experienced by the wing plus body is less than that of the plain wing by 8%.…”

“…For designing a balance, as an input to the design, the loads that are expected on the model need to be specified. A survey of the literature on slab delta wings showed that the maximum values of the aerodynamic coefficients that can be expected at α = 12 • are [8] C N = 0.15, C M = 0.005 and C A = 0.075.…”

“…Except for the data of Olstad [7] for very thick wings and Witcofski and Marcum [8] for t/c greater than 0.083, data on slab delta wings are not satisfactory because of the interference effects of the lee-side balance housing used by all other investigators.…”