A Method for Designing the Helicopter Skid Landing Gear by a Criterion of Landing Impact Energy Absorption

This paper presents the results of calculating the energy criterion being proposed by an example of two types of skid landing gear for a multipurpose helicopter of transport category.     

Energetic and Broad Band Spectral Distribution of Emission from Astronomical Jets

Emission from astronomical jets extend over the entire spectral band: from radio to the TeV γ-rays. This implies that various radiative processes are taking place in different regions along jets. Understanding the origin of the emission is crucial in understanding the physical conditions inside jets, as well as basic physical questions such as jet launching mechanism, particle acceleration and jet composition. In this chapter I discuss various radiative mechanisms, focusing on jets in active galactic nuclei (AGN) and X-ray binaries (XRB) environment. I discuss various models in use in interpreting the data, and the insights they provide.     

Simulation of elastoplastic deformation of helicopter skid landing gear springs

A technique is proposed for calculating the stress strain state and power intensity of helicopter skid landing gear springs operating under conditions of dynamic loading taking into account a physically and geometrically nonlinear deformation scheme. Using real helicopter structures, the sufficient reliability of the technique developed is confirmed by comparison with experimental results. The solution convergence conditions are analyzed by the method proposed under approximation of the material deformation diagram with stressed spline.     

Laminarization of a boundary layer on the perforated surface with blind damping cavities in an accelerating flow

In this paper, a decrease of turbulent pulsations of velocity in a boundary layer and the coefficient of friction drag for an accelerating flow on the perforated surface with blind damping cavities is experimentally found. We generalize the mathematical model of partial boundary layer laminarization [1], which is based on the experimental data [2, 3] obtained earlier on a decrease of the friction drag coefficient and deformation of average velocity profiles in the stabilized section of flow in the perforated tube with blind damping cavities.     

Changes of properties of the materials of spacecraft solar arrays under the action of atomic oxygen

A procedure is developed for physical and chemical modeling and investigation of the weight, geometrical, and thermo-optical characteristics of polymer paneling materials of solar arrays and of the electric power of solar cells under the prolonged action of supersonic fluxes of atomic oxygen in orbit. The behavior of changes in the material characteristics as a function of the integral fluence of atomic oxygen is found. It is established that the electric power of solar cells is virtually invariable within the errors of measurements under irradiation by atomic oxygen flux with a fluence of no higher than 5 · 10²¹ cm^?2.     

AE9, AP9 and SPM: New Models for Specifying the Trapped Energetic Particle and Space Plasma Environment

The radiation belts and plasma in the Earth’s magnetosphere pose hazards to satellite systems which restrict design and orbit options with a resultant impact on mission performance and cost. For decades the standard space environment specification used for spacecraft design has been provided by the NASA AE8 and AP8 trapped radiation belt models. There are well-known limitations on their performance, however, and the need for a new trapped radiation and plasma model has been recognized by the engineering community for some time. To address this challenge a new set of models, denoted AE9/AP9/SPM, for energetic electrons, energetic protons and space plasma has been developed. The new models offer significant improvements including more detailed spatial resolution and the quantification of uncertainty due to both space weather and instrument errors. Fundamental to the model design, construction and operation are a number of new data sets and a novel statistical approach which captures first order temporal and spatial correlations allowing for the Monte-Carlo estimation of flux thresholds for user-specified percentile levels (e.g., 50th and 95th) over the course of the mission. An overview of the model architecture, data reduction methods, statistics algorithms, user application and initial validation is presented in this paper.     

Minimization of aircraft engineering enterprise losses

A technique for the econometric analysis of aircraft engineering enterprise activity results using the annual and quarterly reports is presented. A reliable nonlinear form of the objective function of losses optimized by the gradient descent method is obtained.     

On the Radial Evolution of Alfvénic Turbulence in the Solar Wind

The observations at different solar distances and latitudes, collected in the past three decades, and the results obtained from more and more sophisticated numerical simulations allowed us to reach a good understanding on many aspects of the complex phenomenon of solar wind turbulence. Moreover, new interesting insights in the theory of turbulence have been obtained, in the past decade, from the point of view that considers a turbulent flow as a complex system, where chaotic behavior and well-established scaling laws coexist. This review aims to provide a quick overview on the state of art in this research field with particular focus on local generation mechanisms.     

A technique for low-frequency balancing of two-console high-speed turbomachine rotors

Special features of two-console rotor dynamics are considered. The advanced technique for low-frequency element-by-element balancing of high-speed console turbomachine rotors is proposed.     

Analysis of the vibrating state of parts and assemblies in the high-pressure compressor of an aircraft engine

The results of the experimental studies of the vibrostressed state of blades and angular ball bearings in the high-pressure compressor used in a turbofan engine of the NK-8 family are presented.