In order to increase the efficiency of a rocket jet propulsion, it is necessary to increase the pressure in the combustion chamber. However, the higher the pressure is in the combustion chamber, the more difficult it is to supply fuel in it through the nozzles using a turbopump unit. The rotation speed of a modern turbopump unit, its mass and overall dimensions become prohibitive. Therefore, engine engineers have the proposal to abandon the traditional calm (deflagration) combustion of fuel, and to replace it with with detonation (combustion with explosions). The jet propulsion with continuous detonation combustion of fuel, which loads the support in the frequency range of 1000 ... 10000 Hz, has the promising outlook in rocket and space technology. Such high-frequency loading is accompanied by the so-called Auger effect, when the modulus of elasticity of the material of a thin-walled structure decreases by 10 times. The nature of high-frequency loading of thin-walled structures has not been studied sufficiently. The results of experimental analysis of high-frequency loading of a cylindrical-shell-and-ring assembly in the frequency range 1000...8000 Hz are represented. It is common way to use the hypothesis of the possibility of Fourier separation of variables in order to solve the boundary value problem of high-frequency loading of aircraft elements. The detected frequency shifts were 40 Hz approximately. It is commensurate with the distance (in frequency) between adjacent vibration tones.

Experimental modal analysis is an important stage in the development of a flying vehicle structure. In the experiment, the eigenfrequency of the structure is identified by a corresponding resonance peak of its amplitude-frequency response characteristic. Different sensors in the vibration machine provide different amplitude-frequency response characteristics. The resonance peaks obtained through different sensors for one and the same eigenfrequency of the structure are located with a frequency shift of approximately 1 Hz. This frequency-shift effect is an obstacle for the experimental modal analysis of structures with closely located oscillation modes. This paper explains the frequency-shift effect using the particle approach. A particle is a point mass, and a structure is a system of particles connected by springs, with each particle associated with its own structural model. Each particle has a “right” for its own resonance and “lives” in its own parallel reality. Each particle is associated with an acceleration sensor. The number of simultaneously considered models is equal to the number of sensors. The obtained modal-analysis results are related only to the corresponding particle. Newton’s third law of the particle interaction is not used in full when assessing the particles’ interaction. The action and reaction forces are still applied to different particles along the same line in the opposite directions, but these forces are different. Modal-analysis simulation is limited to the 2-DOF and the 3-DOF oscillation models.

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The paper considers problem of the attacking drone avoiding interception at the final stage of its flight. Duration of this stage is a few seconds. Drones are flying to the target, explode and die. The literature traditionally considers the attack and the anti-aircraft drones independently. It is proposed to identify the attacking and the anti-aircraft drones as a single oscillatory system with the antagonistic components. Antagonistic components are connected using the non-Newtonian elastic element. Test game with a high-explosive drone, test game with a fragmentation drone and 2D salvo game were considered. The game in this case is not a traditional minimax optimization problem, but appears to be simulation of the compromise unstable motion mode. Salvo of three attack drones in the 2D games is aimed against three stationary targets. Anti-aircraft salvo includes two high-explosive and two fragmentation drones. The attacking drones “know nothing” about the anti-aircraft target distribution; thus, each of them “avoids” the anti-aircraft drones simultaneously. One operator is playing. Therefore, the game has only two parameters, i.e. two different stiffness coefficients of any non-Newtonian elastic element. The non-Newtonian oscillatory system under study is non-oscillatory. There are violations of the well-known oscillation theorems of the oscillations theory: with the increasing rigidity, the system oscillation frequency drops, the oscillation forms acquire additional nodes, etc.

The article presents the results of box-shaped shell tests in the frequency range of 10…50 Hz. According to the Fourier hypothesis, the peaks of the amplitude-frequency characteristics corresponding to different points of the box-like shell are to lie on the same vertical straight line. An analysis of the results of frequency tests revealed significant deviations from the Fourier hypothesis. It is shown that in resonance (of the same tone) different points of the box shell oscillate with different frequencies. Frequency shifts are about 2 Hz.