• 한국항공운항학회지
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• 제22권3호
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• pp.60-67
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• 2014

Technical history of VTOL aircraft is examined from the early helicopter appearance to recent experimental rotorcraft in order to distinguish the core issues of those aircraft. Performance and technological challenges of some VTOL aircraft such as tilt rotor, convertiplane, gyroplane, and coaxial helicopter are discussed. As a new generation high performance rotorcraft, Sikorsky X2 is intensively investigated. Considering the developmental history of X2, the autorotational ability at high speed is recognized as a core technology. Analytic method of autorotation and some results are shown and presents research subjects related to the future Korean high performance rotorcraft.

• 한국군사과학기술학회지
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• 제23권4호
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• pp.311-318
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• 2020

This study investigates the performance and blade airloads for a rigid coaxial rotor of high-speed compound unmanned rotorcrafts. The present compound unmanned rotorcraft uses not only a rigid coaxial rotor, but also wings and propellers for high-speed flights. For the rigid coaxial rotor in this work, CAMRAD II, a rotorcraft comprehensive analysis code, is used to study the performance at a flight speed of up to 250 knots and blade section lift forces at 230 knots. As the flight speed increases, the rotor power decreases; however, the power of propellers increases to overcome the drag force of a rotorcraft in high-speed flight. The effective lift-to-drag ratio of a rotor has the maximum value of about 11.6 which is much higher than the value of the conventional helicopter. The blade section lift forces of the upper and lower rotors at 230 knots show the similar variation trends for one rotor revolution, and the impulses because of the aerodynamic interaction between both rotors are observed.

• International Journal of Aeronautical and Space Sciences
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• 제11권2호
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• pp.69-79
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• 2010

This paper describes the experimental framework for the control system design and validation of a rotorcraft unmanned aerial vehicle (UAV). Our approach follows the general procedure of nonlinear modeling, linear controller design, nonlinear simulation and flight test but uses an indoor-installed multi-camera system, which can provide full 6-degree of freedom (DOF) navigation information with high accuracy, to overcome the limitation of an outdoor flight experiment. In addition, a 3-DOF flying mill is used for the performance validation of the attitude control, which considers the characteristics of the multi-rotor type rotorcraft UAV. Our framework is applied to the design and mathematical modeling of the control system for a quad-rotor UAV, which was selected as the test-bed vehicle, and the controller design using the classical proportional-integral-derivative control method is explained. The experimental results showed that the proposed approach can be viewed as a successful tool in developing the controller of new rotorcraft UAVs with reduced cost and time.

• 한국항공운항학회지
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• 제21권3호
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• pp.27-40
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• 2013

Rotorcraft operating in the domestic aviation safety techniques are applied CRM training is conducted but, aircraft accidents caused by human factors has not shown a declining trend. Thus, knowledge of aviation safety and human factors for the spread of awareness of improved rotorcraft flight operations department managers to understand the complexity of nature and culture, and to perform high-risk mission helicopter pilot study of local activation and enhance safety awareness research was conducted in order to. In this study, the development direction of CRM training studies in order to identify the leading NOTECHS (Non-Technical Skills; non-technical pilot skills) of the four categories as the independent variable and the dependent variable corresponding to the resulting effect on the key variables awareness of the differences were studied. In addition, the direction and strength of the relationship were analyzed to determine the relationship of each independent variable to assess the impact on the dependent variable regression analysis was performed. Pilot training and evaluation of non-technical skills related to the teaching reflected in the CRM training and assessment must be carried out with 5 star rating scale was preferred. Therefore, to meet our country rotorcraft operating environment 'NOTECHS' aviation safety by developing training programs reflected in the educational process, implementation, and periodic training and assessment is done in future research on this analysis and feedback is done to reflect the specific performance expect.

• International Journal of Aeronautical and Space Sciences
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• 제18권1호
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• pp.154-164
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• 2017

This work conducts a validation study for the XH-59A helicopter using a rigid coaxial rotor system in order to establish the techniques of the conceptual design and performance analysis for the lift-offset compound rotorcraft. As a tool for conceptual design and performance analysis, NDARC (NASA Design and Analysis of Rotorcraft) is used for the present study. An assumed mission profile is considered for the conceptual design of the XH-59A. As a validation result of the design, the dimensions and weight of the XH-59A are appropriately designed when compared to the target values since the relative error is less than 0.5%. Then, performance analyses are conducted for the designed XH-59A model with and without auxiliary propulsion in hover and forward flight conditions. The present analyses show good validity since the prediction results compare well with both the flight test and previous analyses. Therefore, the techniques for the conceptual design and performance analysis of the lift-offset compound helicopter are overall considered to be appropriately established. In addition, this study investigates the influence of the lift-offset on the rotor effective lift-to-drag ratio of the XH-59A helicopter with auxiliary propulsion. As a result, the improvement of the rotor effective lift-to-drag ratio can be obtained by appropriately increasing the lift-offset in high-speed flight.

• International Journal of Aeronautical and Space Sciences
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• 제4권1호
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• pp.88-98
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• 2003

Compared to the noise limits (CAN7) specified in ICAO Annex 16 for civil helicopters, the Lynx helicopter equipped with BERP blades has only 0.2 EPNdB margin in the approach case although it has more than 4 EPNdB margin in fly-over and take-off conditions. The objectives of the study described in this paper were to devise a low noise main rotor blade for the Lynx using UEAF combined with the high resolution airload model ACROT. A design requirement is that the new blade, KBERP (Korean BERP) blade should achieve a significant reduction in noise during approach(at least 6EPNdB margin) without any noise penalty in fly-over and take-off conditions and minimal performance penalty. It was decided to investigate a tip modification to the BERP blade, employing the twin vortex concept to reduce the BVI noise and to retain the excellent high speed performance characteristics of BERP. Through the parametric study, the KBERP blade with optimized twin vortices has at least a 9 EPNdB noise margin in approach flight condition with only a small penalty in fly-over and take-off conditions. The KBERP tip is thus a very cost effective wav to reduce BVI noise during approach.

• 한국항공우주학회지
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• 제46권10호
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• pp.823-832
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• 2018

일반적으로 항공기 운동 모델의 충실도는 대상 항공기의 비행시험 결과와 비교하여 검증한다. 따라서 성능 비교를 위한 기준 비행 데이터를 추출하는데, 각종 잡음이 포함된 방대한 양의 비행데이터를 처리하는 것은 많은 인력과 시간이 소요된다. 특히 회전익항공기는 축간 커플링 효과와 후류 간섭 효과 등으로 비선형성이 큰 특성을 가지고 있으며, 제자리 비행, 후진 비행 등의 다양한 기동을 수행하므로 비행 데이터를 처리하는 것이 복잡하다. 본 연구에서는 회전익항공기의 비행 데이터 처리 기준을 정의하고, 데이터마이닝 기법을 이용한 정적 및 동적 비행 데이터 자동 처리를 위한 절차와 방법을 제시한다. 최종적으로 비행데이터를 사용하여 제시한 방법을 검증한다.

• 한국정밀공학회지
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• 제28권12호
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• pp.1388-1396
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• 2011

This paper is focused on the procedure of the development of a micro air vehicle which has vertical take-off and landing capability for indoor reconnaissance mission. Trade studies on mission feasibility led to the proposal of a coaxial rotorcraft configuration as the platform. The survey to provide a guide for preliminary design were conducted based on commercial off-the-shelf platform, and the rotor performance was estimated by the simple momentum theory. To determine the initial size of the micro air vehicle, the modified conventional fuel balance method was applied to adopt for electric powered vehicle, and the sizing problem was optimized with the sequential quadratic programming method using MATLAB. The designed rotor blades were fabricated with high strength carbon composite material and integrated with the platform. The developed coaxial rotorcraft micro air vehicle shows stable handling quality with manual flight test in indoor situation.

• 한국항공우주학회지
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• 제46권2호
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• pp.95-105
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• 2018

차세대 회전익기 개발에서 고속화는 중요한 과제이며, 선행 연구들을 통해 덕트 팬을 가지는 비행체는 고속화 실현 가능성이 높은 형상으로 평가된다. 본 연구에서는 다중 덕트 팬 비행체의 전진 비행시의 유동 특성 및 공력 성능 분석을 위한 전산해석을 수행하였다. 전방 팬의 공력 성능은 자유류 유동과 팬 유입류에 의해 결정되는 반면, 후방 팬의 성능은 전방 팬에서 발생한 유동에 지배적인 영향을 받음을 확인하였다. 전진 속도가 증가하며 전방 팬 입구에서의 유동 박리는 후방 팬보다 먼저 발생하며, 덕트 입구 박리는 팬 추력의 증가를 유도한다. 두 덕트 팬 간의 상호 작용으로 인해 후방 팬에는 상대적으로 정렬된 유동이 유입되므로 박리 이전까지 추력이 꾸준히 감소하고, 전/후방 팬의 추력의 급격한 변화는 동시에 발생한다. 전진 속도에 따라 전체 비행체의 수직력은 감소하였다. 이는 팬 후류에 의한 동체 아랫면 압력 저하가 주요 원인으로 분석되었다.

• 한국항공우주학회지
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• 제33권2호
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• pp.22-31
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• 2005

본 연구에서는 회전익 항공기의 수직 이/착륙 성능과 고정익 항공기의 고속/고효율 순항 비행 성능을 모두 가지는 Canard Rotor/Wing 항공기 최적 형상설계를 수행하였다. CRW 항공기의 특징인 로터/날개 가변 방식과 로터 회전 시 팁 제트를 통하여 회전력을 얻는 점 때문에 기존의 회전익 또는 고정익 사이징 프로그램만으로는 바로 적용이 어렵고 Reaction Driven 로터에 대한 해석 모듈의 추가와 회전익/고정익 비행 모드 해석이 혼합되어야 한다. 따라서 기존의 사이징 프로그램을 바탕으로 로터 성능, 덕트 유동, 엔진 유동 해석 코드를 연결하여 Reaction Driven 로터 성능 해석이 가능하게 하였으며, 비행체 외형상 특징과 임무별 비행특징이 반영되도록 사이징 프로그램을 개발하였다. 1500 lbs급 소형 무인기에 대하여 비행체 사이징을 수행하고 성능에 크게 영향을 미치는 설계변수를 파악하여 최적화 문제를 구성하였고 전역적 최적화 기법을 이용하여 최소 중량을 가지는 CRW 항공기의 최적형상을 도출하였다.