Determination of parameters of rotational motion of the <Emphasis Type="Italic">Monitor-E</Emphasis> spacecraft from the telemetry data on solar batteries’ current

The Monitor-E spacecraft executed uncontrolled flight due to emergency situation, no telemetry information on parameters of the spacecraft’s attitude motion being available. So, the problem arose to determine the spacecraft’s rotational motion from the accessible indirect information—the electric current provided by solar batteries. In this paper the integrated statistical technique is described, that allows one to solve this problem. The values of current, obtained over the time interval some tens of minutes long, have been processed simultaneously by the least squares method using the integration of the equations of spacecraft’s rotational motion. As a result of processing, the initial conditions of motion were estimated, and the spacecraft’s moments of inertia were updated, as well as the angles, specifying solar batteries position in the spacecraft-fixed coordinate system. The results of processing of 12 data sets are presented, which allowed us to reconstruct the actual rotational motion of the spacecraft.     

Study of the mode of angular velocity damping for a spacecraft at non-standard situation

Non-standard situation on a spacecraft (Earth’s satellite) is considered, when there are no measurements of the spacecraft’s angular velocity component relative to one of its body axes. Angular velocity measurements are used in controlling spacecraft’s attitude motion by means of flywheels. The arising problem is to study the operation of standard control algorithms in the absence of some necessary measurements. In this work this problem is solved for the algorithm ensuring the damping of spacecraft’s angular velocity. Such a damping is shown to be possible not for all initial conditions of motion. In the general case one of two possible final modes is realized, each described by stable steady-state solutions of the equations of motion. In one of them, the spacecraft’s angular velocity component relative to the axis, for which the measurements are absent, is nonzero. The estimates of the regions of attraction are obtained for these steady-state solutions by numerical calculations. A simple technique is suggested that allows one to eliminate the initial conditions of the angular velocity damping mode from the attraction region of an undesirable solution. Several realizations of this mode that have taken place are reconstructed. This reconstruction was carried out using approximations of telemetry values of the angular velocity components and the total angular momentum of flywheels, obtained at the non-standard situation, by solutions of the equations of spacecraft’s rotational motion.     

Determination of parameters of attitude motion of a small communication satellite using the data of measurements of current of solar panels

A communication satellite (small spacecraft) injected into a geosynchronous orbit is considered. Flywheel engines are used to control the rotational spacecraft motion. The spacecraft after the emergency situation has passed into a state of uncontrolled rotation. In this case, no direct telemetric information about parameters of its rotational motion was accessible. As a result, the problem arose to determine the rotational satellite motion according to the available indirect information: current taken from the solar panels. Telemetric measurements of solar panel current obtained on the time interval of a few hours were simultaneously processed by the least squares method integrating the equations of rotational satellite motion. We present the results of processing 10 intervals of the measurement data allowing one to determine the real rotational spacecraft motion and to estimate the total angular momentum of flywheel engines.     

Numerical experiments for supersonic and hypersonic flows

This paper contains the results of numerical experiments carried out by means of a modified non-stationary “large particle” method developed for the investigation of properties of both steady and non-steady flows associated with complicated gasdynamic problems. In the solution obtained by numerical analysis one may observe the formation of shock waves, local supersonic zones, separation regions with recirculation, and similar effects. Such phenomena are all of significance to a great number of practical problems.     

Calculation of the Direction of the Braking Impulse to Bring a Returnable Stage into the Desired Region

Cosmic Research - The problem of calculating the direction of the braking impulse to bring the reusable returnable first stage of a launch vehicle into the desired landing region is considered. A...     

To simulation of fan blade out for a high bypass ratio engine

The results of simulating the dynamic characteristics of turbofan engines (TFE) during and after fan blade-out are presented. To solve the tasks, we constructed a nonlinear unsteady engine model that includes the low pressure rotor, high pressure rotor, cases, nacelle with reverse, engine hanger to the pylon, pylon itself, and aircraft hanger of the pylon to the wing. The rotor system model also includes the rolling bearings (stiffness of which is calculated for engine operation in different operating regimes), nonlinear hydrodynamic dampers, and elastic bushes (“squirrel cages”).     

Investigation of the loop combustion chamber

As a result of the experimental-theoretical study of the loop (countercurrent) combustion chamber of the gas turbine engine, the data and theoretical dependences are obtained on the change in the combustion completeness and combustion temperature in various operating modes.