Abstract:

ESDU 87003 derives a simple formula for the wave drag of an aerofoil that requires for its evaluation a knowledge only of quantities on the aerofoil surface. The initial method, known as first-order, used the aerofoil curvature at the foot of the shock, but for cases where the chordwise variation of curvature was rapid or uneven, it was found necessary to extend the method to take account of curvature variation upstream of the shock and in its immediate neighbourhood. The two-dimensional formula was then adapted by simple sweep concepts to determine the wave drag at a local spanwise station of a swept wing and, by integration spanwise, the total wave drag of a wing-body combination. Comparisons were made for aerofoils with wave drag deduced from BVGK calculations and from wind-tunnel data for seven aerofoils. The theoretical results were in good agreement but at low wave drags the experimental data were some 20 per cent less than predicted. The application of the procedure to wings is illustrated with two worked examples for which experimental data were available to calibrate the accuracy of the method. It is seen to overestimate the wave drag by about 10 per cent. The method has been programmed in Fortran, and the program is provided as ESDUpac A8703.