Abstract:

ESDU 01013 predicts for aerofoils the centre of lift position based on thin-aerofoil theory with empirical correction. This is combined with the predicted increment in aerofoil lift coefficient from other Items to estimate the pitching moment coefficient increment. For wings with full-span devices, factors dependent on planform geometry are applied to the pitching moment coefficientincrement on an aerofoil section that is representative of the wing in order to allow for three-dimensional effects. For wings with part-span devices, additional factors are introduced that are dependent on the wing taper ratio and on the spanwise extent of the devices, and the effect of wing aspect ratio and sweep is also accounted for in the procedure. The method covers plain leading-edge flaps, drooped leading edges, slats, sealed slats, and vented and unvented Krüger flaps in combination with plain, split, slotted and multi-slotted trailing-edge flaps. The way the wing must be divided into portions containing either leading-edge devices, trailing-edge flaps, both or none prior to the application of the three dimensional factors is described. The empirical factors that apply in the case of combined deployment have been derived to supplement those available from other Items for individual devices deployed alone. The method applies in free air and at Mach numbers below about 0.2. Sketches illustrate the accuracy of prediction and tables give the ranges of parameters covered in the construction of the method. For aerofoils, 91 per cent of the data for the increment in pitching moment coefficient are predicted to within 0.05.For wings, 95 per cent of the data for the increment in pitching moment coefficient are predicted to within 0.04. Worked examples illustrate the use of the method.