Fig. 10. Polar diagram showing results from three models for determining the profile drag coefficient C_D,pro and the lift coefficient C_L from the `steady' data represented by the lower yellow line. A good model would result in values close to, or slightly above, those of the `early' conditions represented by the upper yellow line. Data are `pooled' values for all wings in the `leading-edge' series. C_h, horizontal force coefficient; C_v, vertical force coefficient; , geometric angle of attack.