IHS ESDU Critical pressure coefficient and component of local Mach number normal to the surface isobar for a swept wing. 75027

ESDU 75027 gives a method, valuable in analysing measured pressure distribution data, for determining regions of supercritical flow on the wing. An equation (also given graphically) is derived for the Mach number of the flow component normal to an isobar by assuming that simple sweep theory can be applied locally; then the required Mach number is that normal to an infinite yawed wing of sweep equal to that of the isobar. An equation is also given (and again shown graphically) for the critical pressure coefficient derived when the Mach number normal to the isobar is unity. The method is thought to give answers not significantly different from those derived by more detailed analysis for incidences up to 10 degrees provided the wing does not combine low aspect ratio and high taper.