W/D S/S BY ESDU 00027

ESDU AERO W.02.04.02 gives curves of form factor as a function of thickness/chord ratio and transition position on three types of aerofoils: conventional sections like the RAF or NACA four figure series with maximum thickness at about 0.3 chord and relatively straight surfaces as the trailing edge is approached, experimental low-drag aerofoils like the EQH or EC types with maximum thickness at 0.5 chord, elliptical leading-edge profile and marked convexity as the trailing edge is approached, and low-drag NACA 65 series with maximum thickness at 0.4 chord and marked concavity as the trailing edge is approached. To obtain the drag of the aerofoils the data for the drag of a flat plate given in ESDU AERO W.02.04.01 is factored by the corresponding value of the form factor obtained from the curves; where transition occurs on the upper and lower surfaces at different positions an average position is assumed.