Abstract:

ESDU 92031 provides an empirical method for straight-tapered wings with leading-edge devices deployed, with or without the deployment of trailing-edge flaps, at freestream Mach numbers up to 0.25. The maximum lift of the wing with high-lift devices retracted is first calculated (by the method of ESDU 89034 which uses predictions for the maximum lift of the aerofoil from ESDU 84026). ESDU 92031 then predicts the increment in maximum lift due to deploying a leading-edge device by applying the increment in two-dimensional flow obtained from ESDU 94027 (for leading edge devices) and ESDU 94028, ESDU 94029, ESDU 94030 or ESDU 94031 (for plain, split, single-slotted or multiple-slotted trailing-edge flaps, respectively) to the most highly-loaded section with allowances for the effects of wing aspect ratio, taper and sweep, and for the effects of part-span (the device must extend to the wing tip) if appropriate. In the absence of a deployed leading-edge device, the deployment of a trailing-edge flap yields an increment in maximum lift, obtained from ESDU 91014, which is reduced due to mutual interference when the devices are deployed together by a decrement obtained from ESDU 92031. The method applies to wing aspect ratios of 3 to 9 and leading-edge sweeps up to 50 degrees with plain, split, or single- or multiple-slotted trailing-edge flaps, and leading-edge flaps, slats or vented or unvented Krueger flaps. It predicts the increment in maximum lift coefficient due to leading-edge devices, alone or in combination with trailing-edge flaps, to within 0.1. A similar accuracy applies for the overall maximum lift coefficient of the wing with deployed high lift devices. Two worked examples illustrate the use of the method.