1. ary-layer development at high Mach numbers on a flat plate at zero angle of attack have been the subject of many investigations. However, existing works at very high Mach numbers, of the order of 20, are mainly restricted to the case of zero angle of attack; for example, Ref s.1-3deal with the weak and strong interaction regimes and, more recently, Refs. 4 and 5, with the "merged layer" region that bridges the gap between a kinetic flow model at the leading edge and the classical hypersonic boundary layer downstream.Atthe same time several theories were suggested,6"9which apply to the weak interaction and strong interaction regions, and it is possible, for example, to calculate surface pressures and heat transfer to an acceptable approximation.