Coupled CFD/CSD simulation of the helicopter main rotor in high-speed forward flight

The helicopter main rotor in forward flight is considered in this paper. The results for rigid blades and elastic blades are compared by the method of coupled simulation. The influence of the structural damping coefficient on the blade in-flight deformation is also considered.     

Optimization of measurements of the Earth’s radiation belt particle fluxes

The Earth’s radiation belts discovered at the end of the 1950s have great scientific and practical interest. Their main characteristics in magnetically quiet periods are well known. However, the dynamics of the Earth’s radiation belts during magnetic storms and substorms, particularly the dynamics of relativistic electrons of the outer belt, when Earth’s radiation belt particle fluxes undergo significant time variations, is studied insufficiently. At present, principally new experiments have been performed and planned with the intention to better study the dynamics of the Earth’s radiation belts and to operationally control the space-energy distributions of the Earth’s radiation belt particle fluxes. In this paper, for spacecraft designed to measure the fluxes of electrons and protons of the Earth’s radiation belts at altitudes of 0.5–10000 km, the optimal versions for detector orientation and orbital parameters have been considered and selected.     

Radiation environment at the end of active functioning of <Emphasis Type="Italic">Vernov</Emphasis> satellite

Factors of radiation environment in near-Earth space in a period from December 1 to 10, 2014 have been analyzed, which could affect serviceability of the onboard systems of Vernov spacecraft.     

Drop test simulation for a helicopter tail landing gear

The paper describes a mathematical model of drop tests on the landing gear of the Ka-62 helicopter. The model is formulated using the multibody system simulation procedure based on the Lagrange equations of the first kind.     

Algorithm of calculating the light airplane flight performance and rational design airscrew parameters at the preliminary design stage

A technique is proposed of calculating the characteristic flight velocities for an airplane with taking into account the nominal performance of a piston engine. We consider an algorithm of design calculation for the airscrew blade geometry (twist angle, chord and optimal angle of attack along blade). Feasible rational versions of design parameters are discussed.     

Influence of exhaust gas recirculation on technical,economic, and environmental performance of high-uprated diesel aircraft engine

This paper considers the problem of reducing the nitrogen oxide emissions in exhaust gases (EG) of the diesel aircraft engine by exhaust gas recirculation (EGR). The main directions in improving a working process of diesel engines with EGR system were formulated.     

A technique for numerical modeling of liquid film disintegration in the pneumatic injector of aircraft engines

A technique for calculating the two-phase flows in the pneumatic injector of the aircraft engine is developed based on solving the model problem, namely, on verification of the two-phase flow model by means of solving the problem of liquid column disintegration under the effect of an incident airflow. We determine the turbulence models that satisfactorily describe the biphase flow processes.     

A Study of Vibrations of Space Station Structure Elements on the Basis of Video Information

Cosmic Research - The results of the Sreda–MKS space experiment showed that visual data on the vibrations of the ISS structural elements allow one to acquire quantitative characteristics of...     

Analysis of the orbit lifetime of CubeSats in low Earth orbits including periodic variation in drag due to attitude motion

It is estimated that more than 22,300 human-made objects are in orbit around the Earth, with a total mass above 8,400,000 kg. Around 89% of these objects are non-operational and without control, which makes them to be considered orbital debris. These numbers consider only objects with dimensions larger than 10 cm. Besides those numbers, there are also about 2000 operational satellites in orbit nowadays. The space debris represents a hazard to operational satellites and to the space operations. A major concern is that this number is growing, due to new launches and particles generated by collisions. Another important point is that the development of CubeSats has increased exponentially in the last years, increasing the number of objects in space, mainly in the Low Earth Orbits (LEO). Due to the short operational time, CubeSats boost the debris population. One of the requirements for space debris mitigation in LEO is the limitation of the orbital lifetime of the satellites, which needs to be lower than 25 years. However, there are space debris with longer estimated decay time. In LEÓs, the influence of the atmospheric drag is the main orbital perturbation, and is used in maneuvers to increment the losses in the satellite orbital energy, to locate satellites in constellations and to accelerate the decay.The goal of the present research is to study the influence of aerodynamic rotational maneuver in the CubeSat?s orbital lifetime. The rotational axis is orthogonal to the orbital plane of the CubeSat, which generates variations in the ballistic coefficient along the trajectory. The maneuver is proposed to accelerate the decay and to mitigate orbital debris generated by non-operational CubeSats. The panel method is selected to determine the drag coefficient as a function of the flow incident angle and the spinning rate. The pressure distribution is integrated from the satellite faces at hypersonic rarefied flow to calculate the drag coefficient. The mathematical model considers the gravitational potential of the Earth and the deceleration due to drag. To analyze the effects of the rotation during the decay, multiple trajectories were propagated, comparing the results obtained assuming a constant drag coefficient with trajectories where the drag coefficient changes periodically. The initial perigees selected were lower than 400 km of altitude with eccentricities ranging from 0.00 to 0.02. Six values for the angular velocity were applied in the maneuver. The technique of rotating the spacecraft is an interesting solution to increase the orbit decay of a CubeSat without implementing additional de-orbit devices. Significant changes in the decay time are presented due to the increase of the mean drag coefficient calculated by the panel method, when the maneuver is applied, reducing the orbital lifetime, however the results are independent of the angular velocity of the satellite.     

Satellite Measurements of Plasma Disturbances and Electric Currents Induced in the Midlatitude Ionosphere Modified by High-Power HF Radio Waves

Cosmic Research - We have analyzed the experimental data obtained in 2016–2019 from the measurements of plasma disturbances and electric currents induced at ionospheric altitudes upon the...