Numerical analysis on the effect of angle of attack on evaluating radio-frequency blackout in atmospheric reentry

2016 ◽  
Vol 68 (11) ◽  
pp. 1295-1306 ◽  
Author(s):  
Minseok Jung ◽  
Hisashi Kihara ◽  
Ken-ichi Abe ◽  
Yusuke Takahashi
2007 ◽  
Vol 14 (2) ◽  
pp. 169-186 ◽  
Author(s):  
S. A. Isaev ◽  
P. A. Baranov ◽  
A. G. Sudakov ◽  
V. B. Kharchenko

Aviation ◽  
2020 ◽  
Vol 23 (4) ◽  
pp. 114-122
Author(s):  
Zbigniew Czyż ◽  
Paweł Karpiński

The paper presents some of the works related to the project of modern gyrocopter construction with the possibility of a short start, known as "jump-start". It also presents a methodology related to numerical calculations using Computational Fluid Dynamics based on ANSYS Fluent three-dimensional solver. The purpose of the work was to calculate the forces and aerodynamic moments acting on the gyrocopter stabilizers. The calculations were carried out for a range of angle of attack α from –20° to +25° and for a sideslip angle β from 0° to 20°. Based on the calculations carried out, analysis of the impact of the slip angle on the load on the stabilizers has been made.


Author(s):  
Fariborz Saghafi ◽  
Afshin Banazadeh

This paper describes a feasibility study of using numerical analysis technique, coupled with a non-linear simulation model of a conceptual fluidic-thrust-vectored unmanned aerial tail-sitter to obtain required thrust deflection angles for a transition manoeuvre in take-off. It also studies the aircraft behaviour in transition subjected to the changes in specified parameters like the thrust value and the engine distance from the centre of gravity. The focus of the research presented was to get the vehicle from zero speed on the ground, in vertical position, to a specified velocity at a specified attitude, in cruise position. It was also specified that, when the vehicle was considered to be flying, it should not reduce speed or be descending and that its angle of attack should remain within a reasonable bound, since extreme angle of attack region causes the simulation and analysis to fall in the uncertain zone. The aircraft pitch attitude was also specified to decrease steadily in every integration step regarding the aircraft velocity. The transition problem was mathematically constructed and coded into Matlab/Simulink for the purpose of analysis and simulation. The inputs to the simulation program were simply series of thrust deflection angles at a number of different instants of time. Simulation was performed for a constant vehicle configuration. It was found that transition was feasible for the thrust to weight ratio around 1.0947 and it took 15 seconds to accomplish, while no attempt was made for time optimization.


Photonics ◽  
2020 ◽  
Vol 7 (4) ◽  
pp. 88
Author(s):  
Bruce A. Webb ◽  
Richard W. Ziolkowski

Radio frequency (RF) blackout and attenuation have been observed during atmospheric reentry since the advent of space exploration. The effects range from severe attenuation to complete loss of communications and can last from 90 s to 10 min depending on the vehicle’s trajectory. This paper examines a way of using a metasurface to improve the performance of communications during reentry. The technique is viable at low plasma densities and matches a split-ring resonator (SRR)-based mu-negative (MNG) sheet to the epsilon-negative (ENG) plasma region. Considering the MNG metasurface as a window to the exterior of a reentry vehicle, its matched design yields high transmission of an electromagnetic plane wave through the resulting MNG-ENG metastructure into the region beyond it. A varactor-based SRR design facilitates tuning the MNG layer to ENG layers with different plasma densities. Both simple and Huygens dipole antennas beneath a matched metastructure are then employed to demonstrate the consequent realization of significant signal transmission through it into free space beyond the exterior ENG plasma layer.


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