Accession Number : AD0826615

Title :   BODIES OF MAXIMUM LIFT AT HYPERSONIC SPEEDS,

Corporate Author : RICE UNIV HOUSTON TX AERO-ASTRONAUTICS GROUP

Personal Author(s) : Miele, Angelo

Report Date : 1968

Pagination or Media Count : 29

Abstract : An investigation of the maximum lift attainable by a conical body flying at hypersonic speeds is presented under the assumption that the pressure distribution is modified Newtonian. The length and the volume are given, and the values of the free-stream dynamic pressure and the factor modifying the Newtonian pressure law are known a priori. First, direct methods are employed, and attention is focused on the class of base sections such that the lift per unit enclosed area is locally maximized with respect to the slope. The contours of this type form a two-parameter family, the parameters being the final radius and the initial angle. The subsequent optimization of these parameters leads one to conclude that the contour maximizing the integrated lift is a flat-bottom triangle whose height equals the body length. Second, the indirect methods of the calculus of variations are used, and it is shown that the solution obtained by direct methods satisfies the Euler equations, the transversality condition, the Legendre condition, and the Weierstrass condition. Therefore, the flat-bottom triangle with the height equal to the body length is the variational solution. Finally, to verify further the maximal properties of the solution obtained, several comparison shapes are considered, specifically: (a) flat-bottom triangle with the height other than the body length, (b) shape with a circular bottom, and (c) rectangular shape. Some elementary inequalities are exploited, and it is proved that the lift of these shapes is smaller than that of the variational solution. (Author)

Descriptors :   (*HYPERSONIC TEST VEHICLES, LIFT), OPTIMIZATION, HYPERSONIC CHARACTERISTICS, CONICAL BODIES, PRESSURE, CALCULUS OF VARIATIONS, FLOW FIELDS, AERODYNAMIC CONFIGURATIONS.

Subject Categories : Fluid Mechanics
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Distribution Statement : APPROVED FOR PUBLIC RELEASE