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: Gasars is a new type of porous cast materials manufactured on the basis of metals and their alloys, some types of ceramics. The basis of the process is gas-eutectic conversion in the system metal-hydrogen. The process of investigation and creation of gasars was commenced in 1979 in the National Metallurgical Academy of Ukraine and is currently continued in Ukraine, the USA, China, Japan, South Korea, Poland and others. The gasars production technological process consists in melting the specified material (metal, alloy, ceramics) in hydrogen (or other active gas) atmosphere at a certain pressure. After the melt is saturated with active gas to a certain concentration, the crystallization process begins at which the pore formation process is launched. As the pores growth occurs perpendicular to crystallization front, the orientation of heat withdrawal influences pores location. So, for example, to obtain radial porosity, radial heat withdrawal is required. To obtain various structures, along with directed crystallization process, the pressure in crystallization chamber is an important factor, which drives the gasar morphology. The porous structure of gasars is diverse, there are the gasars with longitudinal, cylindrical, spherical, conical pores. It is possible to alternate the porosity layers and monolithic metal layers. The dimensions of gasars pores are in the limits from 10 μm to 10 mm at total porosity from 7 to 55 (75%). However, there is a possibility to obtain the pores with smaller diameter. The mechanical properties of gasars have a number of advantages as compared with conventional porous materials produced by different methods. Subsequent processing of the gasars does not differ from analogous non-porous materials, which is also an advantage over conventional porous materials. And in case when the diameter of pores is less than 50 μm, the exceedance of mechanical properties of gasars as compared with monolithic materials of the same chemical composition is observed. This is caused by the fact that the pores were formed during crystallization and at the action of pressure on a gasar, local hardening occurs. At present, the gasars have already found application as light and strong structural materials, filters, heat exchangers, dampers, slide bearings, catalyst elements, friction materials, etc. The use of gasars in space hardware will help to considerably reduce the mass of launch vehicle structural elements without worsening strength properties. The possibility of welding and soldering the gasars allows finding their application in the structure of propellant systems, compressed gas and propellants supply systems, creating filtering elements based on the gasars, including propellant spraying and mixing systems.