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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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International Journal of Aeronautical and Space Sciences
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Journal DOI :
The Korean Society for Aeronautical & Space Sciences
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Volume & Issues
Volume 15, Issue 4 - Dec 2014
Volume 15, Issue 3 - Sep 2014
Volume 15, Issue 2 - Jun 2014
Volume 15, Issue 1 - Mar 2014
Selecting the target year
Wing Design Optimization of a Solar-HALE Aircraft
Lim, JaeHoon ; Choi, Sun ; Shin, SangJoon ; Lee, Dong-Ho ;
International Journal of Aeronautical and Space Sciences, volume 15, issue 3, 2014, Pages 219~231
DOI : 10.5139/IJASS.2014.15.3.219
We develop a preliminary design optimization procedure in this paper regarding the wing planform in a solar-powered high-altitude long-endurance unmanned aerial vehicle. A high-aspect-ratio wing has been widely adopted in this type of a vehicle, due to both the high lift-to-drag ratio and lightweight design. In the preliminary design, its characteristics need to be addressed correctly, and analyzed in an appropriate manner. In this paper, we use the three-dimensional Euler equation to analyze the wing aerodynamics. We also use an advanced structural modeling approach based on a geometrically exact one-dimensional beam analysis. Regarding the structural integrity of the wing, we determine detailed configuration parameters, specifically the taper ratio and the span length. Next, we conduct a multi-objective optimization scheme based on the response surface method, using the present baseline configuration. We consider the structural integrity as one of the constraints. We reduce the wing weight by approximately 25.3 % from that in the baseline configuration, and also decrease the power required approximately 3.4 %. We confirm that the optimized wing has sufficient flutter margin and improved static longitudinal/directional stability characteristics, as compared to those of the baseline configuration.
Sensitivity analysis of transonic flow past a NASA airfoil/wing with spoiler deployments
AKuzmin, lexander ;
International Journal of Aeronautical and Space Sciences, volume 15, issue 3, 2014, Pages 232~240
DOI : 10.5139/IJASS.2014.15.3.232
Transonic flow past a NASA SC(2)-0710 airfoil with deployments of a spoiler up to
was studied numerically. We consider angles of attack from
and free-stream Mach numbers from 0.81 to 0.86. Solutions of the unsteady Reynolds-averaged Navier-Stokes equations were obtained with a finite-volume solver using several turbulence models. Both stationary and time-dependent deployments of the spoiler were examined. The study revealed the existence of narrow bands of the Mach number, angle of attack, and spoiler deflection angle, in which the flow was extremely sensitive to small perturbations. Simulations of 3D flow past a swept wing confirmed the flow sensitivity to small perturbations of boundary conditions.
Added masses computation for unconventional airships and aerostats through geometric shape evaluation and meshing
Tuveri, Marco ; Ceruti, Alessandro ; Marzocca, Pier ;
International Journal of Aeronautical and Space Sciences, volume 15, issue 3, 2014, Pages 241~257
DOI : 10.5139/IJASS.2014.15.3.241
The modern development in design of airships and aerostats has led to unconventional configurations quite different from the classical ellipsoidal and spherical ones. This new class of air-vehicles presents a mass-to-volume ratio that can be considered very similar to the density of the fluid displaced by the vehicle itself, and as a consequence, modeling and simulation should consider the added masses in the equations of motion. The concept of added masses deals with the inertia added to a system, since an accelerating or decelerating body moving into a fluid displaces a volume of the neighboring fluid. The aim of this paper is to provide designers with the added masses matrix for more than twenty Lighter Than Air vehicles with unconventional shapes. Starting from a CAD model of a given shape, by applying a panel-like method, its external surface is properly meshed, using triangular elements. The methodology has been validated by comparing results obtained with data available in literature for a known benchmark shape, and the inaccuracies of predictions agree with the typical precision required in conceptual design. For each configuration, a CAD model and a related added masses matrix are provided, with the purpose of assisting the practitioner in the design and flight simulation of modern airships and scientific balloons.
Visual Target Tracking and Relative Navigation for Unmanned Aerial Vehicles in a GPS-Denied Environment
Kim, Youngjoo ; Jung, Wooyoung ; Bang, Hyochoong ;
International Journal of Aeronautical and Space Sciences, volume 15, issue 3, 2014, Pages 258~266
DOI : 10.5139/IJASS.2014.15.3.258
We present a system for the real-time visual relative navigation of a fixed-wing unmanned aerial vehicle in a GPS-denied environment. An extended Kalman filter is used to construct a vision-aided navigation system by fusing the image processing results with barometer and inertial sensor measurements. Using a mean-shift object tracking algorithm, an onboard vision system provides pixel measurements to the navigation filter. The filter is slightly modified to deal with delayed measurements from the vision system. The image processing algorithm and the navigation filter are verified by flight tests. The results show that the proposed aerial system is able to maintain circling around a target without using GPS data.
Comparison of Global Optimization Methods for Insertion Maneuver into Earth-Moon L2 Quasi-Halo Orbit Considering Collision Avoidance
Lee, Sang-Cherl ; Kim, Hae-Dong ; Yang, Do-Chul ; Cho, Dong-Hyun ; Im, Jeong-Heum ; No, Tae-Soo ; Kim, Seungkeun ; Suk, Jinyoung ;
International Journal of Aeronautical and Space Sciences, volume 15, issue 3, 2014, Pages 267~280
DOI : 10.5139/IJASS.2014.15.3.267
A spacecraft placed in an Earth-Moon L2 quasi-halo orbit can maintain constant communication between the Earth and the far side of the Moon. This quasi-halo orbit could be used to establish a lunar space station and serve as a gateway to explore the solar system. For a mission in an Earth-Moon L2 quasi-halo orbit, a spacecraft would have to be transferred from the Earth to the vicinity of the Earth-Moon L2 point, then inserted into the Earth-Moon L2 quasi-halo orbit. Unlike the near Earth case, this orbit is essentially very unstable due to mutually perturbing gravitational attractions by the Earth, the Moon and the Sun. In this paper, an insertion maneuver of a spacecraft into an Earth-Moon L2 quasi-halo orbit was investigated using the global optimization algorithm, including simulated annealing, genetic algorithm and pattern search method with collision avoidance taken into consideration. The result shows that the spacecraft can maintain its own position in the Earth-Moon L2 quasi-halo orbit and avoid collisions with threatening objects.
Cooperative Guidance Law for Multiple Near Space Interceptors with Impact Time Control
Guo, Chao ; Liang, Xiao-Geng ;
International Journal of Aeronautical and Space Sciences, volume 15, issue 3, 2014, Pages 281~292
DOI : 10.5139/IJASS.2014.15.3.281
We propose a novel cooperative guidance law design method based on the finite time disturbance observer (FTDO) for multiple near space interceptors (NSIs) with impact time control. Initially, we construct a cooperative guidance model with head pursuit, and employ the FTDO to estimate the system disturbance caused by target maneuvering. We subsequently separate the cooperative guidance process into two stages, and develop the normal acceleration command based on the super-twisting algorithm (STA) and disturbance estimated value, to ensure the convergence of the relative distance. Then, we also design the acceleration command along the line-of-sight (LOS), based on the nonsingular fast terminal sliding mode (NFTSM) control, to ensure that all the NSIs simultaneously hit the target. Furthermore, we prove the stability of the closed-loop guidance system, based on the Lyapunov theory. Finally, our simulation results of a three-to-one interception scenario show that the proposed cooperative guidance scheme makes all the NSIs hit the target at the same time.
Study on Vertical Dynamics Compensation for Wobbling Effect Mitigation of Electrostatically Levitated Gyroscope
Lee, Jongmin ; Song, Hyungmin ; Sung, Sangkyung ; Kim, Chang Joo ; Lee, Sangwoo ;
International Journal of Aeronautical and Space Sciences, volume 15, issue 3, 2014, Pages 293~301
DOI : 10.5139/IJASS.2014.15.3.293
We present a study of vertical dynamics control of an electrostatically levitated gyro-accelerometer considering the wobbling effect and propose a tilt stabilization method with newly introduced control electrodes. Typically, a rotor in a vacuum rotates at high velocity, which may create a drift rate and lead to displacement instability due to the tilt angle of the rotor. To analyze this, first we set up a vertical dynamic equation and determined simulation results regarding displacement control. After deriving an equation for drift dynamics, we analyzed the drift rate of the rotor and the wobbling effect for displacement control quantitatively. Then, we designed new sub-electrodes for moment control that will decrease the drift amplitude of wobbling dynamics. Finally, a simulation study demonstrated that the vertical displacement control with the wobbling compensation electrodes mitigated the rotor's drift rate, showing the effectiveness of the newly proposed control electrodes.
Role of Distribution Function in Vibration Related Error of Strapdown INS in Random Vibration Test
Abdoli, A. ; Taghavi, S.H. ;
International Journal of Aeronautical and Space Sciences, volume 15, issue 3, 2014, Pages 302~308
DOI : 10.5139/IJASS.2014.15.3.302
In this paper, a detailed investigation of the random vibration test is presented for strapdown inertial navigation systems (INS). The effect of the random vibration test has been studied from the point of view of navigation performance. The role of distribution functions and RMS value is represented to determine a feasible method to reject or reduce vibration related error in position and velocity estimation in inertial navigation. According to a survey conducted by the authors, this is the first time that the effect of the distribution function in vibration related error has been investigated in random vibration testing of INS. Recorded data of navigation grade INS is used in offline static navigation to examine the effect of different characteristics of random vibration tests on navigation error.
Conceptual design and RCS property research of three-surface strike fighter
Yue, Kuizhi ; Tian, Yifeng ; Liu, Hu ; Han, Wei ;
International Journal of Aeronautical and Space Sciences, volume 15, issue 3, 2014, Pages 309~319
DOI : 10.5139/IJASS.2014.15.3.309
This paper mainly focuses on the conceptual design and stealth performance of the three-surface military aircraft. A three-dimensional (3-D) digital mock-up of the three-surface strike fighter with stealth feature was designed and the schemes of carrying missiles were analyzed in CATIA. Based on physical optics principle and the Method of Equivalent Currents (MEC), a numerical simulation of the RCS feature of the aircraft was carried out with RCSPlus which is a software designed by Beihang University. The paper contributes to the RCS feature analysis of the whole plane and different parts on X-band, S-band and UHF-band and a comparison of RCS feature to Su-37 and T-50 military aircraft is drawn. On X-band, the pitch angle of the incident wave was
, and the result shows: (1) Compared with Su-37 aircraft, the forward scattering RCS of the three-surface strike aircraft was reduced to 14.9%, the side scattering RCS to 9.6% and the back scattering RCS to 40.2%. (2) Compared with T-50 aircraft, the forward scattering RCS was reduced to 38.61%, and the side scattering RCS to 67.26%. This paper should be useful for researchers in conceptual design and stealth technology of the military aircraft.
Study on Anomalous Electron Diffusion in the Hall Effect Thruster
Kwon, Kybeom ; Walker, Mitchell L.R. ; Mavris, Dimitri N. ;
International Journal of Aeronautical and Space Sciences, volume 15, issue 3, 2014, Pages 320~334
DOI : 10.5139/IJASS.2014.15.3.320
Over the last two decades, numerous experimental and numerical efforts have examined physical phenomena in plasma discharge devices. The physical mechanisms that govern the anomalous electron diffusion from the cathode to the anode in the Hall Effect Thruster (HET) are not fully understood. This work used 1-D numerical method to improve our understanding and gain insight into the effect of the anomalous electron diffusion in the HET. To this end, numerical solutions are compared with various experimental HET performance measurements and the effects of anomalous electron diffusion are analyzed. The relationships between the anomalous electron diffusion and important parameters of the HET are also studied quantitatively. The work identifies the cathode mass flow rate fraction, radial magnetic field distribution, and discharge voltage as significant factors that affect anomalous electron diffusion. Additionally, the study demonstrates a computational process to determine the radial magnetic field distribution required to achieve specific thruster performance goals.
Shape and Orifice Optimization of Airbag Systems for UAV Parachute Landing
Alizadeh, Masoud ; Sedaghat, Ahmad ; Kargar, Ebrahim ;
International Journal of Aeronautical and Space Sciences, volume 15, issue 3, 2014, Pages 335~343
DOI : 10.5139/IJASS.2014.15.3.335
An airbag is an important safety system and is well known as a safety system in cars during an accident. Airbag systems are also used as a shock absorber for UAVs to assist with rapid parachute landings. In this paper, the dynamics and gas dynamics of five airbag shapes, cylindrical, semi-cylindrical, cubic, and two truncated pyramids, were modelled and simulated under conditions of impact acceleration lower than
to avoid damage to the UAV. First, the responses of the present modelling were compared and validated against airbag test results under the same conditions. Second, for each airbag shape under the same conditions, the responses in terms of pressure, acceleration, and emerging velocity were investigated. Third, the performance of a pressure relief valve is compared with a fixed-area orifice implemented in the air bag. For each airbag shape under the same conditions, the optimum area of the fixed orifice was determined. By examining the response of pressure and acceleration of the airbag, the optimum shape of the airbag and the venting system is suggested.