Influence of the scale factor on the characteristics of turbopumps of ultra-light launch vehicles’ engines

Currently, the use of ultra-light launch vehicles for launching nano- and microsatellites is actively developing in the world, which requires the creation of engines with relatively low thrust. In this paper, based on criterion dependencies, the change in the characteristics of turbopump units of such engines under the influence of the scale factor was analyzed. It is shown that the specific power of turbopumps of ultra-light rocket engines decreases by 2-4 times compared to launch vehicles of greater mass, which negatively affects the characteristics of the vehicle as a whole. A refined methodology for estimating the mass of turbopumps in terms of low-flow units is presented. It was revealed that when the thrust changes, turbopumps can be scaled according to the criterion of the cavitation coefficient, therefore, when the unit is made smaller, its efficiency changes slightly, and the decrease in specific power with the decrease in thrust can be mainly countered by switching to a gearbox scheme and using pre-pumps.