NACA-RM-A51J11

Abstract

INTRODUCTION <br>At supersonic mach numbers, the airfoil section having minimum drag for a prescribed structural strength or stiffness may have a blunt trailing edge, as has been shown through theoretical considerations by Chapman in reference 1. The two dimensional characteristics of such airfoils of moderate thickness as compared with a more conventional airfoil having a sharp trailing edge have been investigated experimentally at subsonic mach numbers (reference 2). Although the results of that investigation indicated higher minimum drag for the blunt-trailing slope increased at mach numbers where the lift-curve slope decreased for the sharp-trailing-edge airfoil. Thus, it would seem that blunt trailing-edge airfoils may be of some practical value at both both subsonic and supersonic mach numbers. <br>The present investigation was undertaken to evaluate the effect of an increase in trailing-edge thickness on the aerodynamic characteristics of a thin three-dimensional wing in the transonic mach number range. For this investigation the thick trailing-edge airfoils were formed by building up the trailing edge to the desired thickness and then fairing to the original airfoil by straight lines. The forward portion of the circular-arc section remained intact and the resulting airfoil was not one of the optimum sections derived in reference 1.