Abstract:

This Technical Memorandum provides methods to predict the maximum lift coefficient, C_Lmax , for symmetric aerofoil sections.

ESDU 66034 describes the differing relationships between the Reynolds number and the section height at 1.25% chord. The four different types of stall are: thin aerofoil stall, leading-edge stall, combined leading-edge and trailing-edge stall, and trailing-edge stall.

For each of these, the difference in stall development characteristics and the dependence or otherwise on Mach number require different prediction methods for C_Lmax .

ESDU 84026 provides a method for the prediction of C_Lmax at low Mach numbers, whilst ESDU Aero W.01.01.07 provides prediction methods for Mach numbers 0.6, 0.7 and 0.75.

However, it is not clear whether these are intended for prediction of C_Lmax or for useable C_Lmax (often related to the penultimate change in lift-curve slope prior to the stall). The present Technical Memorandum predicts the final maximum value of C_Lmax beyond which there is no increase in CL .

ESDU 20002 provides a description of the flow development and the lift characteristics as the stall develops from the initial departure from a linear characteristic. ESDU 20002 also provides a background to the development of that Data Item which is also relevant to the development of the present Technical Memorandum.

ESDU TM 194 describes the results of an initial investigation into the dependence of wing leading-edge pressures on various parameters.

Format: PDF.