ESDU 84026:1999

ESDU 84026 provides a simple empirically derived method for estimating maximum lift coefficient. The method predicts the increment in lift coefficient by which the maximum exceeds the value at zero incidence, and a prediction method for lift coefficient at zero incidence is included. Graphs of the increment show its variation with aerofoil geometry and Reynolds number for aerofoils with smooth or rough leading-edges; rough here would cover ice formation while smooth includes the level of roughness required just to fix transition. A further empirical factor is provided to extend the method to apply to modern aerofoils with rear loading. The accuracy is assessed in terms of the standard deviation of prediction from experiment for nearly 500 points, sub-divided by aerofoil type, leading-edge condition and Reynolds number. The overall standard deviation was about 0.08. The method is programmed as part of ESDUpac A9315, see ESDU 93015.