• Advances in aircraft and spacecraft science
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• v.4 no.2
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• pp.145-167
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• 2017

The presented paper gives an overview of several projects addressing the experimental characterization and control of the buffet phenomenon on 3D turbulent wings in transonic flow conditions. This aerodynamic instability induces strong wall pressure fluctuations and therefore limits flight domain. Consequently, to enlarge the latter but also to provide more flexibility during the design phase, it is interesting to try to delay the buffet onset. This paper summarizes the main investigations leading to the achievement of open and closed-loop buffet control and its experimental demonstration. Several wind tunnel tests campaigns, performed on a 3D half wing/fuselage body, enabled to characterize the buffet aerodynamic instability and to study the efficiency of innovative fluidic control devices designed and manufactured by ONERA. The analysis of the open-loop databases demonstrated the effects on the usual buffet characteristics, especially on the shock location and the separation areas on the wing suction side. Using these results, a closed-loop control methodology based on a quasi-steady approach was defined and several architectures were tested for various parameters such as the input signal, the objective function, the tuning of the feedback gain. All closed-loop methods were implemented on a dSPACE device able to estimate in real time the fluidic actuators command calculated mainly from the unsteady pressure sensors data. The efficiency of delaying the buffet onset or limiting its effects was demonstrated using the quasi-steady closed-loop approach and tested in both research and industrial wind tunnel environments.

• Journal of Aerospace System Engineering
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• v.17 no.4
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• pp.110-117
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• 2023

In this paper, the optimal placement of the rotary wing's communication and navigation antennas was evaluated by measuring their performance through ground simulations and flight tests. To select the mounting position of the communication and navigation antenna on the helicopter, after considering the shape and characteristics of the airframe, the radiation patterns, coupling analysis, equipment operation profiles, and antenna type analysis were performed for the aircraft-mounted antenna. Based on the analysis results, a procedure for sequentially performing voltage standing wave ratio (VSWR) measurement and antenna pattern test was established through ground and flight tests of the antenna. The systematic performance measurement method and procedure proposed in this paper were verified through ground and flight tests of the Light Armed Helicopter (LAH) system.

• Journal of Advanced Navigation Technology
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• v.27 no.3
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• pp.269-273
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• 2023

Based on the K-UAM roadmap, this study was conducted to select major education and training subjects necessary for the composition of the initial UAM pilot education and training curriculum. Currently, UAM aircraft have similar characteristics to rotorcraft that can take off and land vertically around VTOL functions. Therefore, in this study, the Rotary Wing Pilot Training Curriculum of the Army Aviation School, which represents Rotary Wing Flight Education, was selected as a comparative group, and education and training subjects for initial UAM pilot training were selected. First, a hierarchical structure for the AHP survey was designed based on the Army's rotorcraft pilot education and training subjects, and the AHP survey was conducted by selecting experts from each class. If the education and training subjects given as priorities through AHP analysis are applied to initial UAM pilot training, it is expected to contribute to the effect of education and training and ultimately to the safe operation of UAM.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.6 no.8
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• pp.577-584
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• 2016

UAV(Unmaned Aerial Vehicle), which is autonomous flight without pilots. Recently, UAV is being applied to various fields such as video recording, aerial photogrammetry. In particular, UAV is getting a lot of attention in the field of space-related information because of it's data acquisition speed and economic feasibility. But analytical study of an unmanned air-side technologies are lacking. In this study, the research of equipment for the unmanned aerial surveys and UAV technologies and trend analysis for generation of terrain model and ortho image effectively were performed. As a result, the ways to improve the utilization field of unmanned aerial surveying and processing of fixed-wing and rotary-wing unmanned aircraft. were suggested. If analytical research on generation of terrain models and ortho image will be performed, production efficiency of the geospatial information industry is expected to be significantly increased.

• Journal of Cadastre & Land InformatiX
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• v.48 no.1
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• pp.111-121
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• 2018

RIn this research, digital elevation models, true-ortho image and 3-dimensional digital complied data was generated and evaluated using unmanned aircraft vehicle stereoscopic images by applying photogrammetric principles. In order to implement stereoscopic vision, digital Photogrammetric Workstation should be used necessarily. For conducting this, in this study GEOMAPPER 1.0 is used. That was developed by the Ministry of Trade, Industry and Energy. To realize stereoscopic vision using two overlapping images of the unmanned aerial vehicle, the interior and exterior orientation parameters should be calculated. Especially lens distortion of non-metric camera must be accurately compensated for stereoscope. In this work. photogrammetric orientation process was conducted using commercial Software, PhotoScan 1.4. Fixed wing KRobotics KD-2 was used for the acquisition of UAV images. True-ortho photo was generated and digital topographic map was partially produced. Finally, we presented error analysis on the generated digital complied map. As the results, it is confirmed that the production of digital terrain map with a scale 1:2,500~1:3,000 is available using stereoscope method.

• Composites Research
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• v.27 no.2
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• pp.77-81
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• 2014

In this study, it was performed damage assessment and repair of small scale aircraft adopted on composite. This aircraft adopted the sandwich structure to skin of wing. This study aims to investigate the residual strength of sandwich composites with nomex honeycomb core and carbon fiber face sheets after the open hole damage by the experimental investigation. The 4-point bending tests were used to find the bending strength, and the open hole was applied to introduce the simulated damage on the specimen. The bending strength test results after open hole were compared with the results of no damaged specimen test. In addition, The damaged composite structure was repaired using external patch repair method after removing damaged area. After that, this study presents comparison results of the experimental investigation between the damaged and the repaired specimen. It was found that the bending strength of repaired specimen was recovered up to 95% of undamaged specimen.

• International Journal of Aeronautical and Space Sciences
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• v.13 no.4
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• pp.446-457
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• 2012

Aeroelastic analysis of an aircraft with a high aspect ratio wing for medium altitude and long endurance capability was attempted in this paper. In order to achieve such an objective, various structural models were adopted. The traditional approach has been based on a one-dimensional Euler-Bernoulli beam model. The structural analysis results of the present beam model were compared with those by the three-dimensional NASTRAN finite element model. In it, a taper ratio of 0.5 was applied; it was comprised of 21 ribs and 3 spars, and included two control surfaces. The relevant unsteady aerodynamic forces were obtained by using ZAERO, which is based on the doublet lattice method that considers flow compressibility. To obtain the unsteady aerodynamic force, the structural mode shapes and natural frequencies were transferred to ZAERO. Two types of unsteady aerodynamic forces were considered. The first was the unsteady aerodynamic forces which were based on the one-dimensional beam shape; the other was based on the three-dimensional FEM model shape. These two types of aerodynamic forces were compared, and applied to the foregoing flutter analysis. The ultimate goal of the present research is to analyze the possible interaction between the rigid-body degrees of freedom and the aeroelastic modes. This will be achieved after the development of a reliable nonlinear beam formulation that would validate the current results as well as enable a thorough investigation of the nonlinearity. Moreover, such analysis will allow for an examination of the above-mentioned interaction between the flight dynamics and aeroelastic modes with the inclusion of the rigid body degrees of freedom.

• Journal of Advanced Navigation Technology
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• v.24 no.2
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• pp.73-84
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• 2020

To overcome ground congestions due to growing number of cars, a lot of companies have proposed personal aerial vehicle (PAV). Among PAV, electric vertical take-off and landing (eVTOL) aircrafts capable of vertical take-off and landing with electric power are drawing attention, and their configurations vary from multicopters to tilt ducted fans. This study tries to analyze the characteristics of each eVTOL design configurations. Parasite drag was calculated using component build up method for Vahana, Aurora, Volocopter representing each eVTOL PAV type of tilt-wing, compound, and multicopter. Wetted area and induced drag was calculated using OpenVSP and XFLR5 that are aircraft design and aerodynamic analysis software. The batteries used in the eVTOL PAV was assumed as Tesla 2170 batteries and flight ranges were calculated. Also, energy consumption and maximum flight time for the given mission profile including take-off and landing, cruising segments were compared for each eVTOL.

• Journal of the Korea Convergence Society
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• v.11 no.7
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• pp.151-155
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• 2020

In this study, the velocity distribution and pressure of the flow with the shape of the aircraft were analyzed to investigate its flight performance. In order to compare the flow rate and its pressure applied on the surface of airplane each other, models A and B have the blunt and sharp shapes as the distinctive shapes of airplanes. It can be inferred that the lower the maximum speed of the flow around the airplane, the less resistance the navigation produces, the less fuel consumption, which is more efficient for the sharp model B than the blunt model A. As the result of this study, the wing area and the head part of the body should be designed to withstand the pressure greater than the body. It is shown that the sharp model B can withstand more pressure due to flow than the blunt model A.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.7
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• pp.33-39
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• 2005

A mathematical model, GUNBLAST, of blast waves emitted from a gun muzzle is established, and structural response analyses for the blast load are performed. The blast wave can be divided into two kinds of waves, free field and reflected blast waves. In this research, the free field blast wave model is established by the use of a scaling approach, and the reflected blast wave is calculated by using the oblique shock theory and computational fluid dynamic calculation. GUNBLAST is applied to two kinds of structural models. To investigate the effect of the muzzle distance from a structural surface, the blast waves on a plate for various muzzle distances are compared to uniform loads. Moreover, the transient response analysis of an aircraft wing model with a 12.7mm gun is carried out by using MSC/NASTRAN. From the results, it can be shown that the blast wave can cause broad random vibration and high frequency damage to equipments mounted in the aircraft.