A Summary of Transonic Natural Laminar Flow Airfoil Development at NAE (Resume Des Recherches de l'Ena sur des Profils Aerodynamiques A Ecoulements Laminaires Naturels Transsoniques)

This report contains an analysis of the experimental results obtained from four supercritical natural laminar flow airfoils investigated in the NAE high Reynolds Number Test Facility. The airfoils have maximum thickness to chord ratios of 0.10, 0.13, 0.16 and 0.21 and were designed for a lift coefficient 0.6. Their design Mach numbers were 0.8, 0.76, 0.72 and 0.68 respectively and the design chord Reynolds number was 12.5 million. It was found that all the airfoils showed the presence of a drag bucket close to design conditions and long lengths in some cases about 70 of natural laminar flow at Reynolds number 6.7 million. The minimum drag for the airfoils was found to range from 0. 0045 to 0.0051, representing far lower levels than any airfoil dominated by turbulent boundary layer. It is also indicated that, with transition fixed at about 10 chord, the drag levels were similar to other airfoils with turbulent boundary layers. Keywords Laminar flow airfoils Transonic flow Pitch motion Aerodynamic drag Supercritical airfoils Angle of attack High Reynolds number Canada.