The need to increase the engine specific impulse, lead design engineers to start development of closed cycle engines where gas is combusted in the main combustion chamber after passing through the Main Turbopump Assembly turbine. Trade-off study analysis for turbopumps of different cycles engines was performed for RD-0110 and RD-0124 LOX-kerosene engines, which have the same thrust range. The analysis included comparison of the parameters, design approaches, turbopumps design and development features for gas generator and stage combustion cycle engines.

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Boost turbopumps for a ground test demonstrator engine developed by Pratt & Whitney have been built by Konstruktorskoe Buro Khimavtomatiyi (KBKhA) in cooperation with Pratt & Whitney. The paper discusses design approach, development results and design simplicity of the liquid hydrogen (fuel) and liquid oxygen (oxidizer) boost turbopumps (FBTP and OBTP). The paper describes element-wise experimental development principles used for the boost turbopumps which are based on component sub-assembly level testing in simulated conditions and fluids thus assuring low cost development and excluding the necessity to conduct all the tests with the real propellants. The OBTP and FBTP experimental characteristics are presented in this paper including comparison of the OBTP performance characteristics in water and in liquid oxygen and the FBTP rotor dynamics characteristics throughout the range of operating speeds. Element-wise development allows not only assuring fulfillment of design requirements but also to determine operability margins of the elements and identify the ways for possible design improvements.