NACA-TN-3607

Abstract

Tests of a group of related NACA airfoil sections varying in maximum thickness, design lift coefficient, and thickness distribution have been conducted in a two-dimensional open-throat type of wind tunnel at Mach numbers of 0.3 to about 1.0 ad at corresponding Reynolds numbers from 0.7 x 10⁶ to 1.6 x 10⁶. Normal-force, drag, and pitching-moment coefficients are presented, together with representative schlieren photographs and pressure-distribution diagrams. <br>The results of these tests indicate that at near-sonic speeds the maximum ratio of the normal force to drag ((n/d)_max) approaches the low values theoretically determined for a biconvex airfoil in supersonic flow; contrary to low-speed results the (n/d)_max increased as either the thickness ratio or the camber was decreased. At all Mach numbers the normal-force coefficient for (n/d)_max generally increased with increases in thickness ratio and camber and with forward movement of the position of maximum thickness. The trends of the data in the highest Mach number range indicated that the normal-force-curve slopes of all airfoils tested are approximately equal at Mach number 1.0, the value being about the same as at low speeds.