This work is devoted to the use of detonative combustion of a liquid fuel in technical devices to obtain a jet thrust. The experimental and theoretical aspects of the organization of detonation in heptane/air/oxygen mixtures are considered. The pulsed regime of detonation at a frequency of 50 Hz has been implemented for the first time in a small-size tube (25 mm in diameter and 740 mm in length). The physical and technical methods that could accelerate the deflagration-to-detonation transition have been studied. The influence of thermal activation of a combustible mixture prior to its ignition and of the special form of a porous obstacle on the magnitude of the predetonation distance is established. The degree of this influence depends on the component composition, equivalence ratio, and the degree of filling the tube with a mixture.