ESDU 74009:1997

ESDU 74009 gives curves of lift coefficient increment as a function of wing thickness/chord ratio and flap deflection for a flap chord/wing chord ratio of 0.4. A second graph provides a correction factor for other flap chord/wing chord ratios less than 0.4. An equation corrects those data from two-dimensional to three-dimensional. The curves are based on a correlation of available experimental data that predicts the lift increment in two-dimensional flow to within 10 per cent. The three-dimensional correction has been compared with experimental data from 12 sources and predicts the lift increment to within 10 per cent also. To correct the data for application to part-span flaps ESDU 74012 is used.