By the classical method of the least action the differential equation for the function of the displacement of a solid fuel combustion front has been derived. The solution anaylsis is given here. The theory of the narrow channel with the triangular section burning up in the fuel has been worked out. The experiments on the measurements of the coordinate temperature dependence at the surface of combustion are explained. The theory of the diffusion increase of the condensed particles which were formed as a result of the combustion is formulated. The function of the particle distribution by size has been found. The theory of the explosion of the hollow metal sphere subjected to the external pulsed load has been worked out. The microscopical theory of solid fuel ignition is presented and the power dependence of tau(i) on the temperature of the heated surface has been explained. The theoretical proof has been given and the prediction of the possibility of controlling the combustion process by means of the high-frequency electric field has been made. The theory of the punching of a solid barrier with sharp rods has been offered.