Annotation: One of the primary objectives in designing separation systems for rocket stages is to create a system featuring minimal mass while ensuring the required relative speed of stage separation, achieving minimal thrust diff erence, and preventing contamination of spacecraft surfaces. Based on the results of resolving an optimization problem, the utilization of one pneumatic pusher for stage separation is one of the optimum scenarios, which will enable a several times lighter mass of the separation system due to the signifi cant reduction of the mass of pipelines, the overall mass of the pusher, and the mass of gas bottles and their fasteners. The preliminary analysis of the separation process and the possibility of using a single pneumatic pusher for stage separation was performed using a mathematical model in the form of a system of diff erential equations describing the stage separation process, and through a series of calculations. The calculation results demonstrate that using a single pneumatic pusher to minimize the risk of an emergency requires a substantial reduction of the resistive forces occurring during stage separation. The article reviews the results of ground development testing for the stage separation system utilized in the Cyclone launch vehicles. It simulates an emergency when an abnormal detachment of the structural elements of stages occurs due to a meshing of electrical disconnector covers, resulting in the adapter section rotation by an angle over the allowable value. The article outlines the method for the experimental determination of resistive forces, presents calculated values obtained during the design phase, and compares these values with experimental data. Resistive force components were identifi ed during testing, such as detachment forces for electrical connectors and sealing elements, and friction forces in guiding studs. For the fi rst time in the practice of launch vehicle design, the authors present a separation system that eliminates resistive forces through the use of an alternative complex of electrical disconnectors, featuring noncontact data transfer and allowing for reduced power losses and fewer elements that produce relative speed for the stage separation system, resulting in a signifi cantly lighter overall mass of the system. The article analyzes resistive forces induced by the detachment of sealants. It presents a procedure for the autonomous development testing of joint sealants, which identifi es the relation between their detachment force and layer thickness. A technique for sealant application to the attachment surface has been developed. The test results enabled determining the required thickness of attachment sealants and the optimum application technique. Therefore, the change in the sealant application technique resulted in a 2.3 times lower maximum resistive force during stage separation, which meets the maximum and design values. The results of experiments provide meaningful data for the engineers of stage and booster separation systems for spacecraft and launch vehicles. Furthermore, they confi rm the feasibility of using alternative electrical disconnectors for stage separation.

Annotation: Separation of the spent LV stages is one of the important problems of the rocket technology, which requires the comprehensive analysis of different types of systems, evaluation of their parameters and structural layouts. Basic requirements are specified that need to be taken into account when engineering the separation system: reliable and safe separation, minimal losses in payload capability, keeping sufficient distance between the stages at the moment of the propulsion system start. Detailed classification of their types («cold», «warm», «hot», «cold-launched» separation) is given and their technical substance with advantages and drawbacks is described. Certain types of «cold» and «warm» separation of the spent stages of such rockets as Dnepr, Zenit, Antares, Falcon-9 with different operating principle are introduced – braking with the spent stage and pushing apart two stages. Brief characteristics of these systems are given, based on the gas-reactive nozzle thrust, braking with solid-propellant rocket engines, separating with spring or pneumatic pushers. Development of the separation system for the advanced Cyclone-4M ILV is taken as an example and design sequence of stage separation is suggested: determination of the necessary separation velocity and capability of the separation units, determination of the number of active units, calculation of design and energy parameters of the separation units, analysis of the obtained results followed by the selection of the separation system. Use of empirical dependences is shown, based on the great scope of experimental and theoretical activities in the process of design, functional testing and flight operation of similar systems in such rockets as Cyclone, Dnepr and Zenit. According to the comparative analysis results, pneumatic separation system to separate Cyclone-4M Stages 1 and 2 was selected as the most effective one. Its basic characteristics, composition, overall view and configuration are specified. Stated materials are of methodological nature and can be used to engineer the separation systems for LV stages, payload fairings, spacecraft etc.