Maximum lift of wings with trailing-edge flaps at low speeds.
Abstract:ESDU 91014 gives a method that involves the calculation of two components: the increment in maximum lift coefficient due to flaps is added to the maximum lift coefficient for the wing with flaps undeployed determined from ESDU 89034. The first component is calculated using ESDU 94028, ESDU 94029, ESDU 94030 or ESDU 94031 (for plain, split, single-slotted or multiple-slotted trailing-edge flaps, respectively) applied to the most highly loaded section, factored for the effects of aspect ratio, taper ratio and wing sweep in addition to flap part-span effects. The method was developed using wind-tunnel data from many sources for a wide range of planform parameters (aspect ratios from 3 to 9 and leading-edge sweep up to 50 degrees) for which it was found to correlate the predicted increment generally within 10 per cent and the maximum lift of the wing with flaps deployed to within 5 per cent. It applies for freestream Mach numbers less than 0.25 for plain, split or single- or multi-slotted flaps. Sketches of predictions plotted against test results illustrate the quality of the estimation and a detailed worked example illustrates the use of the method.
|Data Item ESDU 91014|
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|Figure 1||Variation of ηp with λ and η‾|
|Figure 2||Variation of μp with λ and η¯|
|Figure 3a||Part-span factor for plain and split flaps|
|Figure 3b||Part-span factor for slotted flaps|