According to Urbanski's finding in a solid explosive with a density of less than the theoretical maximum density (TMD), the detonation velocity increases if the air contained in the explosive gets replaced by a non-explosive liquid. In order to quantify this observation, the detonation velocities for RDX in combination with ten non-explosive liquids were calculated using the EXPLO5 code (V6.05.04). It could be shown that pressing out the air of a high-explosive powder and replacing the voids with a non-explosive liquid such as ethylene glycol, water or glycerin helped to increase the final detonation velocity.