IHS ESDU Low-speed longitudinal aerodynamic characteristics of aircraft in ground effect. 72023

ESDU 72023 provides a means of estimating the changes in the lift-curve, drag, tailplane lift, and downwash from the wing of an aircraft due to ground effect in incompressible flow. It is assumed that the free-air conditions are known. The data are applicable to any aircraft except those with pointed slender wings, which are considered in ESDU 71007. The equations and graphical data are generally applicable to aircraft with mechanical high-lift devices or having flaps with boundary layer control giving free air lift coefficients less than 4 for wings of quarter chord sweepback less than 45 degrees and for height/chord ratios greater than 0.3. The methods are semi-empirical and in general consider the changes in free air conditions as the ground is approached at constant aircraft lift coefficient and hence changing incidence. In the consideration of lift, however, the changes due to ground effect on incidence at constant lift coefficient or in lift coefficient at constant incidence may be found.