Acoustic and Dynamic Response of Unbaffled Plates of Arbitrary Shape

In this study, a method for determining the effects of fluids on the dynamic characteristics of an aerospace structure and the response of the structure when it is excited by the acoustical loads produced during a rocket launch, has been developed. Elevated acoustical loads are critical in the design of large lightweight structures, such as solar arrays and communication reflectors, because of the high acceleration levels. The acoustic field generated during rocket launch can be considered as a diffuse field composed of many uncorrelated incident plane waves traveling in different directions, which impinge on the structure. A boundary element method was used to calculate the pressure jump produced by an incoming plane wave on an unbaffled plate and the fluid–structure coupled loads generated through plate vibration. This method is based on Kirchhoff’s integral formulation of the Helmholtz equation for pressure fields. The generalized force matrix attributed to the fluid loads was then formulated, taking the modes of the plate in vacuum as base functions of the structural displacement. These modes are obtained using a finite-element model. An iteration procedure was developed to calculate the natural frequencies of the fully coupled fluid–plate system. Comparison of the results obtained using the proposed method with those of other theories and experimental data demonstrated its efficiency and accuracy. The proposed method is suitable for analyzing plates of arbitrary shape subjected to any boundary conditions in a diffuse field for low to medium values of the frequency excitation range.

Research on Shock Acceleration Limit of an Ultra-Stable Optical Cavity for Space Applications Based on the Finite Element Methodology

Ultra-stable optical cavities (USOCs) as fragile precision instruments have many important applications in space. In order to protect them from being damaged during a rocket launch, we analyzed a USOC by means of finite element methodology. The shock acceleration limits that the USOC can withstand in different directions and under various conditions are given. To increase the shock acceleration limit, the midplane thickness and the fixed hole diameter should be selected to be as high as possible. It is worth noting that the launch direction of the USOC should be selected as the horizontal direction, for which the shock acceleration limit that the USOC can withstand is approximately two times that of the vertical direction. In this paper, results provide guidance for the design of USOCs for space applications, especially the design to prevent the damage caused by a shock. The method could then be applied to other space optical cavities, providing a tool to improve the effect of shock at high accelerations.

Chromato-mass-spectrometric identification of asymmetric dimethylhydrazine and N-nitrosodimethylamine

Introduction. Environmental safety is one of the main priorities of state policy. It ensures the legal regulation of relations in space activities to strengthen the defense and security of the Russian Federation and further extension of the international cooperation of the Russian Federation. Material and methods. In the fall areas of the stages of the booster rockets, screening studies were carried out to identify the propellant component 1.1-unsymmetrical dimethylhydrazine in atmospheric air (n=14) and drinking water (n=23), determine its metabolite N-nitrosodimethylamine quantitatively in the residents’ blood (n = 90) living in the surveyed areas before the rocket launch (n = 45) and after the launch (n = 45). Also quantitative determination of the N-nitrosodimethylamine metabolite in the residents’ urine in the observation group (n = 108) was performed. For comparison, there was selected a group of residents not related to rocket and space activities (n = 13). Identification and analysis of samples of atmospheric air, drinking water, and biological media (blood, urine) was performed using Agilent 7890A gas chromatograph (USA) with a 5975C quadrupole mass spectrometric detector (MCD) and a capillary column of the HP-FFAP 30m • 0.25mm • 0.25µm series. Results. The study revealed the absence of asymmetric 1.1-dimethylhydrazine in 100% of analyzed atmospheric air samples. During the observation period, the concentrations of N-nitrosodimethylamine in the range of 0.00039 to 0.001 mg/dm3 were found in drinking water samples that did not exceed the hygienic standard (LOCNDMA 0.01 mg/dm3). N-nitrosodimethylamine in a concentration range of 0.00095-0.346 mg/dm3 was determined in the blood samples of the population. The studies revealed that after the rocket launch, the N-NDMA concentration in the blood was 1.8 times higher than the concentration registered before the rocket launch. In the urine sample of the resident living in the surveyed area, N-nitrosodimethylamine was detected with a high degree of reliability according to the essential ion with mass 74 m/z and confirmatory ion of 42 m/z, and the concentration was quantitatively calculated at a level of C N-DMA = 0.23 μg/ml. The detection of N-nitrosodimethylamine in blood and urine, even in trace amounts, indicates the possibility of exposure. Conclusion. Performed comprehensive studies made it possible to prove the relative safety of the ecological situation in the fall areas of the booster rockets that are located close to settlements when considering the environmental pollution with unsymmetrical dimethylhydrazine and can be used for systematic monitoring.

Computational Nanosatellite Constellations

As rocket launch cadences increase, access to space rises dramatically - setting the stage for the next space industry surge. New, smaller, and less expensive satellites - now "nanosatellites" - can be deployed en masse to form constellations of hundreds, thousands, or even tens of thousands of devices [27, 40, 41, 16, 17, 18, 43]. A constellation of nanosatellites equipped with sensors (e.g., visual or hyperspectral cameras, particle detectors, or magnetometers) and radios provides a first-time opportunity for orbital swarm sensing to synthesize data from the unique vantage point of low-Earth orbit (LEO).

Design, Analysis and Simulation of a Single Stage Rocket (Launch Vehicle) Using RockSim

This project describes the design, analysis, assembly and simulation of a single stage model rocket systems, one designed with traditional subsystems for structural, avionics, combustion chamber and recovery integrated to give a desired altitude. The analysis was based on using Rocksim 9.6 to model the different parts that made up a rocket. Aluminium was used for designing the nose cone, the fuselage and the fin set. The combustion chamber, clamps, and nozzle were designed by making use of steel. Because of the high temperature and pressure being generated from the combustion of propellant, steel was suggested. The main and drogue parachutes were designed using tubular Kevlar. And the bulk-head was designed using Basswood. For the recovering of the rocket after launch, main and drogue parachutes were incorporated into the fuselages.

A completely reusable aerospace system based on subsonic carrier with the return of the first stages to the starting point

The concept of aerospace system based on air launch from subsonic twin-fuselage aircraft and the rocket launch into orbit is investigated. The scheme of aerospace system trajectory providing a return to the starting point both of the carrier and the first rocket stage with liquid-fuel motors is proposed. It was shown that the use of subsonic carrier as a launching platform of the rocket system increases the payload mass by 1.2% of the rocket segment MTOW as compared to autonomous ground take-off. The comparative analysis of three versions of carrier aircraft and three fuel options at the first rocket stage was carried out. Analysis showed that compared to kerosene variant the hydrogen hypersonic booster makes it possible to significantly increase the payload mass while the launching costs stay the same.

Simulation Analysis and Experimental Verification of the Locking Torque of the Microgravity Platform of the Chinese Space Station

The Microgravity Platform (MP) of the Chinese Space Station is locked and released by Lock-or-Release (L/R) mechanism on both sides. In order to ensure the safety and reliability of the MP under the vibration environment during the rocket launch, the L/R mechanism must output the appropriate locking torque value. Based on the structural characteristics of the Scientific Experiment Cabinet (SEC), this paper proposes a method of evaluating locking torque by combining theory with experiment, and the relationship between locking force and locking torque of L/R mechanism is proved that the locking force on both sides can reach 2000 N at 25 Nm driving torque. Finally, it is verified by vibration test that the locking torque obtained by this method can effectively guarantee the safety and reliability of the MP under vibration environment.