Spiral descent of an unmanned aerial vehicle

An intensive unsteady spiral descent of an unmanned aerial vehicle with an approach to target (object) at the design altitude and specified minimal flight speed is considered. The decisive equations describing the motion of the FV center-of-mass are solved by time intervals. The influence of controlling parameters on the spiral radius, the maneuver speed and time is studied.     

Estimation of potential abilities of middle atmosphere density measurements from a near-Earth orbit within the UV wavelength range

Analysis of errors in atmospheric density measurements by lidar on board the ISS is performed. It is shown that using as the lidar transmitter a Nd:YAG laser with moderate parameters of emission at a wavelength of 353 nm and a receiving mirror diameter of 0.4 m, it is possible to cover with a 10% measurement error a height range, on average, from 40–60 km and 30–40 km in the nighttime and daytime, respectively, down to the troposphere. Working with emission at 266 nm with a 10% error, it is possible to move to the heights of the mesosphere (70 km) and penetrate the atmosphere down to a height of 40 km. Thus, the use of two harmonics makes it possible to assimilate the height range of atmospheric density measurements from on board the ISS beginning from 70 km and down to the troposphere.     

Verification of shielding effect by the water-filled materials for space radiation in the International Space Station using passive dosimeters

The dose reduction effects for space radiation by installation of water shielding material (“protective curtain”) of a stack board consisting of the hygienic wipes and towels have been experimentally evaluated in the International Space Station by using passive dosimeters. The averaged water thickness of the protective curtain was 6.3 g/cm². The passive dosimeters consisted of a combination of thermoluminescent detectors (TLDs) and plastic nuclear track detectors (PNTDs). Totally 12 passive dosimeter packages were installed in the Russian Service Module during late 2010. Half of the packages were located at the protective curtain surface and the other half were at the crew cabin wall behind or aside the protective curtain. The mean absorbed dose and dose equivalent rates are measured to be 327 μGy/day and 821 μSv/day for the unprotected packages and 224 μGy/day and 575 μSv/day for the protected packages, respectively. The observed dose reduction rate with protective curtain was found to be 37 ± 7% in dose equivalent, which was consistent with the calculation in the spherical water phantom by PHITS. The contributions due to low and high LET particles were found to be comparable in observed dose reduction rate. The protective curtain would be effective shielding material for not only trapped particles (several 10 MeV) but also for low energy galactic cosmic rays (several 100 MeV/n). The properly utilized protective curtain will effectively reduce the radiation dose for crew living in space station and prolong long-term mission in the future.     

Search for the OH (X(2)Pi) Meinel band emission in meteors as a tracer of mineral water in comets: detection of N(2)(+) (A-X)

We report the discovery of the N(2)(+) A-X Meinel band in the 780-840 nm meteor emission from two Leonid meteoroids that were ejected less than 1000 years ago by comet 55P/Tempel-Tuttle. Our analysis indicates that the N(2)(+) molecule is at least an order of magnitude less abundant than expected, possibly as a result of charge transfer reactions with meteoric metal atoms. This new band was found while searching for rovibrational transitions in the X(2)Pi electronic ground state of OH (the OH Meinel band), a potential tracer of water bound to minerals in cometary matter. The electronic A-X transition of OH has been identified in other Leonid meteors. We did not detect this OH Meinel band, which implies that the excited A state is not populated by thermal excitation but by a mechanism that directly produces OH in low vibrational levels of the excited A(2)Sigma state. Ultraviolet dissociation of atmospheric or meteoric water vapor is such a mechanism, as is the possible combustion of meteoric organics.     

An overview of RADOM results for earth and moon radiation environment on Chandrayaan-1 satellite

The RADiatiOn Monitor (RADOM) is a miniature dosimeter-spectrometer that flew onboard the Chandrayaan-1 lunar mission in order to monitor the local radiation environment. Primary objective of the RADOM experiment was to measure the total absorbed dose, flux of surrounding energetic particles and spectrum of the deposited energy from high energy particles both en-route and in lunar orbit. RADOM was the first experiment to be switched on after the launch of Chandrayaan-1 and was operational until the end of the mission. This paper summarizes the observations carried out by RADOM during the entire life time (22 October 2008–31 August 2009) of the Chandrayaan-1 mission and compares the measurement by RADOM with the radiation belt models such as AP-8, AE-8 and CRRESS.     

Effect of heating on the dynamic behavior of a shell with partially damaged thermal insulation

The influence of aerodynamic heating of the aircraft skin with a partially damaged thermal insulation on its dynamic behavior is studied numerically. The study is carried out in two steps: the first step is to determine the temperature field in the shell; the second step is to measure the values of structure material characteristics depending on its temperature, to correct the stiffness matrix of the skin, and to solve the dynamics problem. The examples are considered.     

A technique of computer-aided synthesizing a finite element model of wing center section and outer wing torsion box joint for a transport aircraft

A technique of synthesizing the finite element model of the flange joint of the outer wing torsion box with the wing center section for a transport aircraft is presented. The technique is based on the functional decomposition principle, in which the general model of wing torsion box is synthesized from the separate substructure models including the flange joint. It has been shown that the manual input is significantly reduced, when the computer-aided synthesis is applied. This made it possible to cut time of synthesis and decrease the probability of error occurrence.     

A technique of design analysis for the gas turbine engine regenerator with complanar channels according to the heat flow and hydraulic resistance

A technique is presented for design analyzing a regenerative plate heat exchanger with complanar channels. Also derived is the formula for optimum relationship of flow areas for gas and air branching channels.     

Analysis of stresses in a cylindrical shell under transverse local loading

The solution is obtained based on the differential equations for the general theory of shells and approximate equations that are the components of the method of asymptotic synthesis. Numerical results are presented.     

Analysis of a coaxial gas ejector

In this paper, the results of investigating a coaxial gas ejector without increase of passive flow pressure are presented. A technique for calculation of coaxial ejectors has been developed. This investigation has resulted in the optimal structure of ejector with a high value of ejection coefficient.