The Flow and Force Characteristics of Supersonic Airfoils at High Subsonic Speeds
NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS LANGLEY FIELD VA LANGLEY AERONAUTICAL LABORATORY
Pagination or Media Count:
An investigation has been conducted at subsonic Mach numbers in the Langley rectangular high-speed tunnel on five supersonic airfoils and for comparison, on two subsonic airfoils. Two-dimensional data were obtained by pressure measurements and schlieren photographs at angles of attack from 0 to 4 deg for Mach numbers between 0.30 and 0.90 for these 6-percent-thick symmetrical airfoils. The results indicated that the drag coefficients are generally higher at subsonic Mach numbers for the supersonic airfoils than for the subsonic airfoils, but the normal-force and pitching-moment characteristics of those supersonic airfoils having their maximum thickness located at the 0.7-chord station would diminish the problems generally encountered in longitudinal control at high Mach numbers. The investigation also revealed the occurrence of an unusual flow phenomenon at the leading edge of the supersonic airfoils at the higher Mach numbers. This phenomenon, through the elimination of an extensive separated-flow condition over the forward part of the airfoil, effected a rather sudden increase in normal-force coefficient and in some cases a decrease in the drag coefficient.