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: The use of servo drives on flying vehicles determines the requirements to their dynamic characteristics. The problems of dynamics of drive with jet motor are not practically covered in publications. The task arises of selection of structure and parameters of devices consisting of several subsystems whose dynamic characteristics must be brought into agreement with each other in optimal way. The purpose of this work is to develop mathematical dependences for calculation of dynamic characteristics. The functional arrangement of the drive is considered consisting of jet motor based on Segner wheel with de Laval nozzle, mechanical transmission, pneumatic distributing device – jet pipe controlled by electromechanical converter. The layout is presented of mechanical segment of servo drive with jet motor with screw-nut transmission. The dynamic model is presented and the algebraic relations to determine natural frequencies of the drive are given. The motion equations of output rod at full composition of load are given. Using Lagrange transformation as applied to ball screw transmission, the expression for reduced mass of output element was derived. The reduced mass of load depends on the jet motor design and exerts basic influence on the drive’s natural frequencies. The evaluation is given of reduced mass change from the jet motor moment of inertia and reducer transmission coefficient. Based on the proposed algorithms, the dynamic characteristics of servo drive were constructed: transient process and amplitude-frequency characteristic. The drive has relatively low pass band, which is explained by the value of reduced mass of load.

Annotation: During experimental investigation of the dynamic characteristics of a pneumatic test bench for testing liquid rocket engine high-flowrate automatic units, the effect was detected of 20-35% sound speed increase in the gas flow moving along the channel with corrugated wall (metal hose) which is a part of test bench drain system. The article presents the results of experiments and the task of theoretical justification of the effect is solved. It is indicated that its causes may be two mutually complementary factors – a decrease of gas compressibility at eddy motion and oscillations of metal hose wall. The physical model is considered that describes variation of gas elasticity and density in the conditions of high flow vorticity. It is supposed that in the near-wall layer of the channel, toroidal vortexes (vortex rings) are formed, which move into turbulent core of the flow where their size decreases and the velocity of rotation around the ring axis of torus increases. The spiral shape of the corrugation ensures also axial rotation, which increases vortexes stability. The intensive rotation around the ring axis creates considerable centrifugal forces; as a result, the dependence of pressure on gas density and the sound speed increase. The mathematical model has been developed that describes coupled longitudinal-lateral oscillations of gas and channel’s corrugated shell. It is indicated that in the investigated system, two mutually influencing wave types are present – longitudinal, which mainly transfer gas pressure pulses along the channel and lateral ones, which transfer the shell radial deformation pulses. As a result of modeling, it has been ascertained that because of the lateral oscillations of the wall, the propagation rate of gas pressure longitudinal waves (having the same wave length as in the experiments at test bench) turns out to be higher than adiabatic sound speed.