IHS ESDU Wing lift increment at zero angle of attack due to deployment of single-slotted flaps at low speeds. 93019

ESDU 93019 presents an empirical method that depends on determining the increment for an aerofoil representative of the wing and applying factors to allow for three-dimensional and part-span effects. ESDU 94030 is used to predict the increment for the aerofoil, depending on the extended deployed chord. That increment is factored by the ratio of the wing to aerofoil lift curve slopes obtained respectively from ESDU 70011 and ESDU Aero W.01.01.05, thereby accounting for aspect ratio, taper and sweep effects. Finally, part-span factors are applied that depend on the spanwise centre of pressure of the loading due to incidence obtained from ESDU 83040. The range of parameters for which the method was validated are tabulated and include aspect ratios of 3.7 to 9, taper ratios from 0.2 to 1, leading-edge sweep up to 48 degrees, Mach numbers up to 0.25, and flap deflections of 10 to 45 degrees. Sketches show the correlation between experimental results drawn from the literature and predicted results; for all results, 90 per cent were correlated within 15 per cent while for part-span cases alone 80 per cent of the data were correlated to within 5 per cent. A worked example illustrates the use of the method.