Annotation: The paper presents the variation of parameters of gas-vapor mixture of hypergolic rocket propellant components in a filling tank in the process of rocket propellant components filling into it with “closed drainage” depending on tank filing coefficient and initial parameters of environment in the tank.

Annotation: The article dwells on development and study of the multifunctional operations while preparing propellant components for launch vehicle tank filling by high-boiling propellant components at the neutralization stations. The article considers the preparation of propellant for filling the launch vehicle stages with high-boiling propellant components of nitrogen tetroxide (oxidizer) and unsymmetrical dimethyl hydrazine (fuel) in terms of propellant saturation with helium and denitrogenation. Usually these issues refer to the common technology of propellant preparation and are tackled sequentially: first, propellant is drained into the filling tank of the filling system, then the propellant is denitrogened, for example purging the propellant by helium under atmospheric pressure in the tank, then propellant is saturated with helium to the given concentration by bubbling helium in the propellant, maintaining the set pressure of helium in the tank. This technology significantly complicates the process of propellant preparation, increases helium consumption, as well as the amount of the generated vapor, which requires recycling in the neutralization units. This article studies multifunctional operations, where the propellant is simultaneously drained from delivery vehicles, saturated with helium and denitrogenated. Amount of residual nitrogen in the propellant and the main direction of deep denitrogenation of the propellant are calculated. Amount of generated vapor and consumed helium are determined. The process of propellant draining by extrusion, maintaining the given pressure in the tank and alternating the propellant drain on the closed vent device (compression) and open vent device (decompression) is studied. As a result, the theoretical justification of multifunctional operations in preparation of high–boiling propellant components to fill the launch-vehicle stages is presented.