• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.9
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• pp.823-831
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• 2011

According to the development of loading equipments, it is usual to change or replace the existing stores. It has been known that pylon-mounted under stores strongly affect aircraft dynamics characteristics due to the change of aerodynamics. To predict the aerodynamics and aero-elasticity is essentially requested with considering the configuration and shape of external stores during the development of aircraft and/or external stores. In this paper, computational fluid dynamics and computational structure dynamics interaction methodology are applied for prediction of aerodynamic characteristics for F-5 aircraft's horizontal tail with various shape of external stores. FLUENT and ABAQUS were used to calculate fluid and structural dynamics. Code-bridge was made base on the globally supported radial basis function to execute interpolation and mapping. As a result, even though the aeroelasticity of the horizontal tail slightly changes according to the shape of external store, the flutter was not occurred at the considered flight conditions in this study.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.3
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• pp.204-212
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• 2015

The infrared lock-on range of target aircraft plays a critical role in determining the aircraft survivability. In this investigation, the effects of various UAV engine nozzle configurations on the aircraft lock-on range were theoretically analyzed. A virtual subsonic aircraft was proposed first, based on the mission requirement and the engine performance analysis, and convergent-type nozzles were then designed. After determining thermal flow field and nozzle surface temperature distribution with the CFD code, an additional analysis was conducted to predict the IR signature. Also, atmospheric transmissivity for various latitude and seasons was calculated, using the LOWTRAN code. Finally, the lock-on and lethal envelopes were calculated for different nozzle configurations, assuming the sensor threshold of the given IR guided missile. It was shown that the maximum 55.3% reduction in lock-on range is possible for deformed nozzles with the high aspect ratio.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.2
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• pp.129-138
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• 2017

This paper has been shown for the extraction of Doppler signature from the radar signal for an air-breathing targets tracked in the ground radar. For the extractions, a Doppler resolution is confirmed from mathematical modeling of PT(pulse train) waveform. Doppler signatures of air-breathing target are varied to radar aspect angle of engine and are determined from physical parameter of jet engine. To confirm such Doppler signatures, the radar signal reflected from the air-breathing target is obtained by our radar signal storage. After this extraction, radar aspect angle of engine has estimated from tracking information. Relative differences of Doppler signatures to radar aspect angle of engine is verified from these results and Doppler profiles for radar target identification appliance are presented.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.5
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• pp.57-64
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• 2005

Modern versions of supersonic jet fighter aircraft using digital flight-by-wire flight control system receive aircraft flight condition such as altitude, airspeed and AoA(angle of attack) from IMFP(Integrated Multi-Function Probe). IMFP sensors data have triplex structure using three IMFP sensors. An air data reconfiguration mode is applied to a T-50 flight control law to guarantee the aircraft flight stability when 2 or 3 IMFP sensors data are invalided. In this study, linear analysis and HQS(Handling Quality Simulator) pilot simulation are performed to analyze flight stability when the air data reconfiguration mode is applied to the control law. And we propose an example that the air data reconfiguration mode is applied to the control law due to second failure of IMFP during T-50 flight. It is found that the aircraft flight stability is not affected when the T-50 flight control law is changed to the air data reconfiguration mode.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.5
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• pp.623-629
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• 2020

This study examined the airflow field around a gun port on the flight condition of gunfire to verify the aircraft performance and safety effects and gun gas rate, path according to the options of diverter configuration. The gun port diverter not only effectively lowered the heat generated by gunfire but also effectively discharged the gun gas upwards. The path of gun gas can be changed according to its configuration. According to the optional configuration of the rear-gun-port diverter, the flow rate, path, and pressure of the gun gas were analyzed during gunfire. An analysis of the internal velocity distribution and the temperature change of the gun port revealed a rapid decrease in flow rate through the rear diverter according to the option configuration. The forward flow rate showed a similar tendency with little change. This ensures that the gun gas generated during gunfire has a sufficient flow distance from the aircraft surface, regardless of the rear gun port diverter's optional configuration. The flow stagnation of gun gas according to the option configuration of diverter had a great influence on the internal temperature rise of a gun port.

• Aerospace Engineering and Technology
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• v.10 no.1
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• pp.175-182
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• 2011

Optimized design was performed for a subsonic aircraft wing. The subsonic aircraft is dual turbo-prop and carrying less than 100 passengers. The cruise speed is Mach 0.6. The design was performed by two stages. The first stage is to decide the height of horizontal tail by analyzing the directional stability with Vorstab and then, the optimized wing configuration was selected with Piano, a optimizer commercially available. Fluent, a commercial CFD software was utilized to predict the aerodynamic performance of the aircraft. Drag of the aircraft was minimized with maintaining constant lift for cruise. The optimization reduced 10 counts from the initial wing configuration.

• Proceeding of EDISON Challenge
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• 2013.04a
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• pp.425-430
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• 2013

본 연구에서 전산유체해석 프로그램인 EDISON_CFD를 이용하여 차세대 항공기 날개 형상으로 각광받고 있는 초음속 비행조건을 갖는 Busemann 형식의 복엽기 형상에 대한 공력특성을 연구하였다. 날개는 압축성 조건에서 2차원 에어포일로 간략화 하여 모델링하였으며, 마하수에 따라 발생하는 충격파와 팽창파의 상호작용을 통한 소닉붐의 감소 형태를 분석해 보고, 마하수에 따른 항력계수를 얻어내었으며, 익형과 항력계수, 소닉붐의 상관관계를 분석하여 초음속항공기에서 복엽기 형상이 가지는 장단점에 대하여 연구하였다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.5
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• pp.41-49
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• 2005

This paper discusses the test procedure, instrumentation, verification methodology and the results of the ground vibration test(GVT) performed on the KF-16D aircraft to estimate experimentally dynamic characteristics of the aircraft. The modal tests for 7 external store configurations were conducted to estimate effects of external stores on the aircraft vibration modes. To emulate free-free boundary conditions the test aircraft was mounted on its landing gear structure with deflated tires during the GVT. The airframe modal tests were done by burst random excitations with 6 to 8 shakers and about 200 accelerometers. Frequency response functions(FRFs) were measured for each test, and the FRFs were reduced and analyzed to identify the dynamic parameters interested. The analyses were carried out in two steps. To extract modal parameters such as, frequencies and damping ratios, the poly-reference least square complex exponential method was used in the time domain. The mode shape coefficients were estimated with the least squares frequency domain method to identify the vibration modes.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.2
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• pp.22-31
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• 2005

A design study was conducted for a new concept aircraft(Canard Rotor/Wing: CRW) that has the capability of dual mode flight, a rotorcraft and a fixed wing mode. The CRW can show a vertical take off/landing and a high speed/efficiency cruise performance simultaneously. It is not surprising to develop a new sizing code for this class of aircraft because conventional sizing codes developed solely for either the rotary wing or the fixed wing aircraft are not adequate to design a dual mode aircraft operated both by the rotary wing through tip jet effux and the fixed wing lift. Thus, a new design code was developed based on the conventional sizing code by adding some features including rotor performance, duct flow, and engine flow analysis, hence could eventually predict the performance of reaction driven rotor, the flight performance and the flight characteristics. The various design parameters were investigated to find their influences on the flight performance then, a small UAV(Unmanned Aircraft Vehicle) of 1500 lbs class was optimally designed to have minimum weight using the developed sizing code.

• Defense and Technology
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• no.10 s.164
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• pp.48-51
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• 1992

항공기 비행품질에 영향을 주는 설계분야는 크게 3가지로 항공기 형상, 조종체계 및 조종실 배치로 분류됩니다. 이들 3가지 설계분야 중에서 조정실의 운용자 인간공학적인 요구 사항을 고려하지 않으면 항공기 운용성 품질중에 3분의 1이 감소될수 있습니다 항공기를 개발할때에 개발자는 그 항공기를 운용하는 운용자의 인체, 생리, 심리, 습관 등을 고려해, 항공기 조종실의 인간공학적 최적화 설계 및 배치를 개발초기단계부터 적용해야 합니다. 항공기의 조종실의 인간공학적 최적화 설계 및 배치를 개발초기단계부터 적용해야 합니다. 항공기의 조종실 품질은 조종사가 항공기 비행 임무를 수행할 때에 항공기 비행을 위한 용이한 정보 인식, 용이한 정보 결심 및 용이한 조종의 특성을 조종사에게 제공할 때 항공기 비행 품질이 좋아질 것입니다