ESDU 97002 provides an introductory review of those Items in the Aerodynamics Series that deal with the changes in lift, pitching moment and drag of a two-dimensional aerofoil or a wing due to the deployment of high-lift devices. In general, the effects of high-lift devices on the basic aerofoil or wing lift and pitching moment coefficients and on the drag coefficient at zero lift are represented by increments in those quantities caused by a given device deflection. The methods given in the Data Items are largely empirical, being based on extensive wind-tunnel data.

For devices that do not appreciably increase the effective wing area, early tests suggested that the increments were practically independent of the test conditions such as wind-tunnel turbulence and Reynolds number. Provided that the stall region was avoided, a slight variation of the lift and pitching moment coefficient increments with angle of attack could be neglected.

For devices that substantially increase the effective wing area, it was found that if the lift and pitching moment coefficient increments were analysed on the basis of the extended area then they too were practically independent of test conditions and varied only slightly with angle of attack. Furthermore, if they were considered as functions of the device deflection angle and the ratio of the device chord to the extended aerofoil or wing chord, they formed a consistent family with the increments of corresponding devices that do not extend the chord. The effect of wing area extension on the profile drag coefficient increments may be neglected provided that the area extension is small. For systems involving large area extensions it is again necessary to base initial calculations on the extended area.

The recent analysis now included in the Data Items shows that the lift coefficient increment at maximum lift coefficient has a Reynolds number dependence. Furthermore, the prediction of the lift and pitching moment coefficient with angle of attack needs to include an effect of Reynolds number and a non-linear effect of angle of attack, to provide substantial improvement over the assumption of a linear variation. If the ratio of device chord to wing chord and the dimensionless wing section geometry are not constant along the device span, an estimate must be made using a strip theory.

Most Items contain an Accuracy and Applicability Section that discusses the reliability of their prediction methods. This should be consulted when each individual Item is used. In the absence of any explicit statement, comparisons of experimental and predicted values for the increments in lift, pitching moment and profile drag coefficients suggest that the errors involved in the use of the methods will not exceed +/-10% in most cases. All Items contain one or more worked examples.