Design of a rapid transit to Mars mission using laser-thermal propulsion

The application of directed energy to spacecraft mission design is explored using rapid transit to Mars as the design objective. An Earth-based laser array of unprecedented size (10-m diameter) and power (100 MW) is assumed to be enabled by ongoing developments in photonic laser technology. A phased-array laser of this size and incorporating atmospheric compensation would be able to deliver laser power to spacecraft in cislunar space, where the incident laser is focused into a hydrogen heating chamber via an inflatable reflector. The hydrogen propellant is then exhausted through a nozzle to realize specific impulses of 3000 s. The architecture is shown to be immediately reusable via a burn-back maneuver to return the propulsion unit while still within range of the Earth-based laser. The ability to tolerate much greater laser fluxes enables realizing the combination of high thrust and high specific impulse, making this approach favorable in comparison to laser-electric propulsion and occupying a parameter space similar to gas-core nuclear thermal rockets (without the requisite reactor). The heating chamber and its associated regenerative cooling and propellant handling systems are crucial elements of the design that receive special attention in this study. The astrodynamics and the extreme aerocapture maneuver required at Mars arrival after a 45-day transit are also analyzed in detail. The application of laser-thermal propulsion as an enabling technology for other rapid transit missions in the solar system and beyond is discussed.

Numerical analysis of the support platform for an unmanned aerial vehicle

The study investigates a thin-walled support platform for an unmanned aerial vehicle, i.e. aluminum beams connected by flat bars and angle irons. The construction is a kind of frame for a propulsion unit of the designed aircraft which is a combination of a multi-copter and a gyrocopter. This construction was tested for various load patterns to investigate the stresses and strains its profiles are connected. The load patterns correspond to different operation modes of the propulsion system, and the finite element method (FEM) and the SolidWorks software were used for the numerical calculations. The research was done for elastic operation of the individual components of the support platform. The analysis enabled to verify the state of stresses on the critical spots of the construction and to develop a construction for ground and flight tests to verify the correct operation of the propulsion control system and optimize its operation in different flight states.

Mathematical model for assessing lateral stability of articulated tracked vehicles

The article considers the problem of increasing transport productivity, operational reliability and safety during cargo transportation by using articulated tracked vehicles and road trains with active trailers. The influence of the introduction of an electromechanical drive, the modernization of the propulsion unit and the steering control system on the lateral stability of an articulated tracked vehicle is analyzed. A mathematical model is described for calculating the lateral stability of the chassis of articulated tracked vehicles used in the regions of the Far North, Arctic and Antarctic. The model is based on developments carried out for the chassis of an articulated wheeled vehicle. The model allows calculating to determine the key geometric and kinematic parameters of the rotation, taking into account the action of external forces. The use of holonomic constraints in determining the critical speed of movement is determined by the physical picture of the beginning of overturning, which corresponds to the achievement of the critical folding angle of the sections. This approach makes it possible not to use empirical coefficients when assessing the instantaneous position of the center of gravity of the system, the center of rotation, the radius of rotation of the center of mass, and the critical speed of the chassis. The moment of the beginning of the rollover is determined by the disappearance of the normal reaction under the link caterpillar. The onset of lateral sliding is determined by the lateral force exceeding the lateral adhesion limit.

Features of slopes overcoming by walking devices

For mobile robots designed to work in extreme conditions, an important characteristic is the value of the overcoming slope. For wheeled and tracked vehicles, the angle of the overcoming slope is limited by the adhesion properties of the soil. The walking device can provide overcoming of higher slopes, since the analogue of the adhesion coefficient for walking machines, with a large footprint track depth, can be significantly greater than 1. The paper discusses the results of experimental studies of the features of overcoming slopes by a walking device in weak soil conditions. When mobile robots overcoming inclines, they may overturn or slide downhill. It is shown that on soft soils the sliding of walking machines downhill is unlikely because of significant deformations of the soil under the support elements. On the other hand, the deformation of the soil worsens the resistance of the walking vehicle to overturning. A method of increasing resistance to overturning by controlling the position of the robot body by separately regulating the conditional clearance of walking mechanisms is considered. The possibility of adjusting the clearance in the propulsion unit on the basis of Umnov-Chebyshev cyclic walking mechanisms is shown. Climbing slopes requires a certain amount of traction. The values of the additional power and the force characteristics of the walking device’s drive necessary for successful overcoming of slopes have been determined. The results of the work can be demand in the development of walking machines and mobile robots. Key words Mobile robots, walking machines, interaction with the ground, traction and coupling properties, overcoming slopes, tipping resistance, mathematical modeling, field tests. Acknowledgements Research was partially supported by RFBR and the Administration of the Volgograd region, research projects no. 19-08-01180 a, 19-48-340007 p_a.

Specificities of landing propulsion system jets’ gas dynamic effects on re-entry vehicle and ground surface during landing

The re-entry vehicle that is part of the new generation piloted spacecraft being developed in RSC “Energia” is designed to land on ground with the help of parachute-reactive landing system. One of the parts of this system is the propulsion unit that helps reduce the descend velocity just before touchdown. Knowledge of gas dynamics of jets formed by combustion products of working propulsion unit is essential for designing its regime. This paper contains results of numerical simulation of the landing process of re-entry vehicle with active propulsion unit near the ground. Among the acquired data are pressure distributions over the landing area and over the surface of the re-entry vehicle. Obtained results are necessary for determining optimal configuration and regime of the propulsion unit. Key words: landing propulsion system, re-entry vehicle, jet gas dynamics.

EXPERIMENTAL DEVICE FOR RESEARCHING THE TECHNOLOGY OF ANCHOR-CABLE MOVERS POSITIONING

The features of the design of the experimental device with an anchor-cable propulsion unit are considered. An algorithm for discrete interaction with soil is synthesized. Determination of the features of the hardware implementation of the control system.