Annotation: The paper gives reasons for conducting experimental works to determine lateral force caused by eccentricity and skew of SRM thrust vector, considers the configuration of fixed test stand for respective experimental works with vertical position of motor axis and describes the fixed test stand operation principle.

Annotation: This paper describes the configuration of the rig, designed to fasten the solid-propellant rocket engine (hereunder referred to engine) during their testing, with engine thrust measurements by force transducers. It is determined that rig is the important link in the measurement chain, which directly impacts the thrust measurements, values of which will be used for calculation of the most important engine characteristics (for example, total burn). It was observed that when engine starts the basic mode of operation the thrust-measuring system of the rig is impacted by the dynamic loading caused by the engine thrust, which results in the occurrence of the oscillating processes in the rig, therefore it is important to know the behavior of these oscillating processes to estimate their impact on the thrust measurement during the design of the rigs and their thrustmeasuring systems. It is shown that if there is no procedure in the design practice to define the mode of oscillations in the rig it is rational to do it analyzing experimental thrust – time curves when different engines start the basic mode of operation. Number of experimental thrust (displacement of the engine/rig moving part) – time curves are provided for analysis when four different engines with different ballistic characteristic and capabilities start the basic mode of operation. Oscillating processes in the rig distort the physical behavior of the thrust, which requires additional analysis of the data following the tests, but since the oscillations subside rapidly, they will not significantly affect the calculation of the total burn. It is also observed that frequency of oscillations of the moving part of the rig, registered by the motion sensor, coincides with oscillation frequency, registered by the force transducer, moreover stable behavior of the oscillating processes, registered by the force transducer of the same engines, when they started the basic mode of operation, indicate the stable behavior of those engines and stable performance of the rig.

Annotation: This paper describes the firing rig test of the solid rocket motor, fastened to the rig in order to measure the thrust level. It is shown that when the motor enters the steady-state mode, the rig with solid rocket motor starts experiencing mechanical oscillations due to the sudden thrust build-up. Motion of the oscillating system is studied under the impact of the linearly or suddenly increasing impulse load. Mechanical oscillations damping is considered on the basis of the viscous friction model. Procedure of the analytical modeling of the damped oscillations is suggested for the complex pattern of the loading variations, based on the fundamental principle of superposition, according to which the motor displacement during the oscillating motion is considered as sum of displacements due to the impact of the impulsive, sudden and linearly increasing loadings. This procedure simulates different time variations of thrust as motor enters the steady-state mode. Oscillating motion with parameters of the oscillating system and thrust change with time option have been simulated as they were realized during the firing rig tests of one of the solid rocket motors. Simulated and experimental (thrust sensor readings) curves of the elastic force were compared, which showed the qualitative and quantitative conformity of the suggested model of oscillations to the actual oscillations of the solid rocket motor, installed in the rig during the firing rig test. Values of the initial thrust, initial impulse and other simulation parameters were updated, adjusting the simulated curve of the elastic force to the experimental one. It was concluded that simulation of the elastic oscillations of the solid rocket motor in the rig using the suggested analytical model will enable more reliable definition of the initial thrust of the motor and its time behavior, impulse loading due to the separation of the plug and used elements that separate with it. Application of the suggested procedure of motor oscillations simulation in the phase of rig design will enable more detailed prediction of the occurring processes as well as the estimation of parameters of the individual elements, units and rig as a whole.

Annotation: The advanced design of SRM test rig is considered the use of which improves the quality of measurement of motor power parameters and increases the amount of test data. It is shown, due to which this was achieved. The technique is proposed for assessment of rig operation stability when measuring the lateral thrust.

Annotation: The information on Yuzhnoye SDO experience in designing and operation of special equipment for testing of SRM of various classes is presented, the description and analysis of results of this equipment operation are given.

Annotation: This article dwells on results of firing bench testing of the solid-propellant rocket engine (SPRE), fastened to the thrust-measuring assembly stand. It is shown that when engine enters the steady-state mode of operation, plane (forward and rotation) vibrations of the SPRE can take place in the assembly stand due to the sudden pattern of thrust generation and displacement of the center of mass of the vibrating system from the engine axis. These vibrations distort measured values of engine thrust and pattern of its change versus time. The purpose of this work is to simulate the oscillating processes of the engine atop the assembly stand to single out in the distorted values of the measured thrust the components related to the processes in the engine and components, which are introduced into the thrust measurement by the oscillating processes in the system “assembly stand – engine”. Model of vibrating system is suggested, which consists of two rigidly connected bodies, containing elastic links, enabling forward and rotary motion and limited by the rigidity of the links. Mathematical model of the vibrating system is developed. Internal forces and moments acting in oscillatory system are defined. Method of numerical simulation of plane vibrations within the limits of the developed model is suggested. Plane vibrating motion and elastic force curve (curve based on force sensor readings) were simulated in thrust-measuring system for different cases of thrust curve and values of vibrating system parameters. Resonance condition was simulated and mutual influence of elastic parametrical link between forward and rotary vibrations was established. Impact of thrust-measuring system rigidity on peak values of force sensor readings was found out. Elastic force vibrations in thrust-measuring system with vibrating system parameters were simulated including variant of thrust change versus time, implemented during firing bench tests of one of the SPRE. It is shown that registered simulation results recreate thrust measurement results in pattern and values obtained by the force sensor during the firing bench tests, and owing to this, it was concluded that oscillating process parameters, assumed in the model, meet the actual ones. It is concluded that simulation provides objective interpretation of the thrust curve, reliable and comprehensive analysis of engine run during firing bench tests, more detailed and exact design of the assembly stand.