An approximate theory on the phenomena of interaction between the shock wave and the laminar boundary layer on an insulated flat plate at hypersonic speeds has been formulated. Results on the rate of growth of the boundary layer thickness and the rate of decay of the shock wave strength have been found for M_1^(2(2+w)R_1^-1 = O(1). A new set of formulae for the average skin friction coefficient, C_F, over an insulated flat plate at hypersonic speeds has been obtained. Calculations on the basis of the new C_F formulae yield the data shown in Figs. 5 and 6. Contrary to the conventional theory which predicts a steady decrease in C_F as M_1 increases, the present results indicate that C_F may increase with M_1 at hypersonic Mach numbers
