Accession Number : AD0825504

Title :   OPTIMUM AIRFOILS AT MODERATE SUPERSONIC SPEEDS. PART I. PRELIMINARY CONSIDERATIONS,

Corporate Author : RICE UNIV HOUSTON TX AERO-ASTRONAUTICS GROUP

Personal Author(s) : Miele, Angelo

Report Date : 1968

Pagination or Media Count : 17

Abstract : The determination of optimum two-dimensional airfoils at moderate supersonic speeds is considered using linear theory and second-order theory. Three cases are investigated: (a) the airfoil of minimum drag at zero angle of attack, (b) the airfoil of minimum drag at zero lift, and (c) the airfoil of maximum lift-to-drag ratio. It is assumed that the length is given and that various constraints are imposed on the thickness, the enclosed area, the moment of inertia of the contour, and the moment of inertia of the enclosed area. If linear theory is employed, the minimum drag airfoil is symmetric with respect to the chord. The maximum lift-to-drag ratio airfoil is also symmetric with respect to the chord and identical with the minimum drag airfoil regardless of the constraints imposed on the thickness, the enclosed area, the moment of inertia of the contour, and the moment of inertia of the enclosed area. If second-order theory is employed and the analysis is confined to symmetric shapes, the minimum drag airfoil and the maximum lift-to-drag ratio airfoil are identical, regardless of the constraints imposed on the thickness, the enclosed area, the moment of inertia of the contour, and the moment of inertia of the enclosed area. Finally, if second-order theory is employed and the analysis is extended to arbitrary shapes, the minimum drag airfoil is still symmetric with respect to the chord. However, the maximum lift-to-drag ratio airfoil is asymmetric and, therefore, not identical with the minimum drag airfoil. (Author)

Descriptors :   (*SUPERSONIC AIRFOILS, OPTIMIZATION), DRAG, ANGLE OF ATTACK, LIFT, TWO DIMENSIONAL FLOW, SUPERSONIC CHARACTERISTICS, MOMENT OF INERTIA, THICKNESS, SLENDER BODIES, PRESSURE, SKIN FRICTION, THEORY.

Subject Categories : Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE