Aerodynamics of Wing Sections for Airplanes 340081
THIS paper, which has been awarded the Wright Brothers Medal for 1933, considers first the air forces acting on airfoil sections, their origin, and the nature of the differences between the air forces acting on an ideal airfoil section and on an actual one. These differences, which are due primarily to the action of viscosity, are considered in detail because they distinguish the desirable from the undesirable sections.
The effects of viscosity are discussed in relation to the air-flow about the section as affected by a variation of the dynamic scale or Reynolds Number of the flow. Separation of the flow from the airfoil surface, which produces the most marked deviations from the ideal flow, is discussed in detail, considering the effects of varying the Reynolds Number and the initial turbulence of the air.
Finally, the paper considers the variation of the aerodynamic properties of sections with changes in the section shape. These results are given from an analysis of the data from tests of 78 related airfoils in the N.A.C.A. variable-density wind tunnel at one value of the Reynolds Number. They provide the information required to make a more rational choice than heretofore possible of the most suitable section for a given application.