Annotation: Being a final executive element of rocket control systems, a hydraulic actuator is at the same time the main source of various non-linear dependencies in rocket dynamic design whose availability dramatically com plicates theoretical analysis of their dynamics and control systems synthesis. The required accuracy and complexity of mathematical models of hydraulic servo mechanisms are different for different design phases of guided rockets. The paper deals with the simplest models of hydraulic servo actuators intended to calculate rocket controllability and to define requirements to response and power characteristics of the actuators. To calculate the rocket stability regions and to evaluate own stability of servo actuators, a linearized mathematical model of hydraulic servo actuator is used that takes into account the most important parameters having impact on stability of the servo actuator itself and on that of the rocket: hardness of working fluid, stiffness of elastic suspension of the actuator and control element, slope of mechanical characteristic of the actuator in the area of small control signals, which, as full mathematical model analysis showed, is conditioned only by dimensions of initial axial clearances of slide’s throats. The full mathematical model constructed based on accurate calculations of the balance of fluid flow rate through the slide’s throats allows, as early as at designing phase, determining the values of most important static and dynamic characteristics of a future hydraulic actuator, selecting optimal characteristics of slides based on specified degree of stability and response of servo actuator and conducting final modeling of rocket flight on the integrated control system test benches without using real actuators and loading stands. It is correct and universal for all phases of rockets and their control systems designing and testing. Using this mathematical model, the powerful actuators of a line of intercontinental ballistic missiles with swinging reentry vehicle and the main engines actuators of Zenit launch vehicle first stage were developed. The results of their testing separately and in rockets practically fully comply with the data of theoretical calculations.

Annotation: The article considers the procedure for evaluation of acoustic stressing parameters at the observation point nearby the launch vehicle nose cone when passing the sectors with maximum velocity heads and close to 1 Mach numbers. And the problem is set to determine the overall sound pressure level and the corresponding levels in octave and 1/3-octave frequency bands. Procedure under consideration is based on the semi-empirical dependency of characteristics of the wideband aerodynamic noise, which occurs during the launch vehicle flight at high velocities due to the turbulent pressure fluctuations and dimensionless aerodynamic parameters of the main stream. General idea of this approach is to establish relation of the velocity heads with wall pressure fluctuations in the boundary layer, calculating shear stress (friction) on the shell surface based on relationships applicable in the boundary layer theory and engineering experience. Attempts of development of similar calculation models go back to the early efforts, dedicated to the study of the aeroacoustics of the launch vehicle in flight. Main advantages of the procedure are its simplicity and versatility since it can be used to determine the acoustic loads around the payload fairings of launch vehicles of different sizes and shapes within the wide range of flight velocities and altitudes.