• Journal of Biosystems Engineering
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• 제35권5호
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• pp.302-309
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• 2010

Aerial application using an unmanned agricultural helicopter would allow precise and timely spraying. The attitude of a helicopter depends on a number of dynamic variables for roll-balanced flight. Laterally tilting behavior of a helicopter is a physically intrinsic phenomenon while hovering and forwarding. In order to balance the fuselage, the rotor should be counter-tilted, resulting in the biased down-wash. The biased spraying toward right side causes uneven spray pattern. In this study, a raised tail rotor system for the roll-balanced helicopter was studied. Thrust of the tail rotor system was measured and theoretically estimated for the fundamental database of the roll-balanced helicopter design. The estimated tail thrust and roll-moment would be used to design the raising height of tail rotor and roll balancing dynamics. The unmanned agricultural helicopter required the tail rotor thrust of about 39.2 N (4.0 kgf) during hovering with a payload of 235.4 N (24 kgf). A raised tail rotor system would compensate for the physical tilt phenomena. A further attitude control system of helicopter would assist roll-balanced aerial spray application.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1136-1141
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• 2008

The helicopter rotor system generates lift, thrust, maneuvering force and moment to the helicopter with the torque and pitch control force transferred from the main rotor hub/control. And the tail rotor system generates the thrust for yaw axis control of the helicopter with the torque and pitch control force transferred from the tail rotor hub/control. Ground whirl test shall be performed to verify the compliance of requirement performance test and dynamic test of rotor blade and hub/control. This paper describes a design of whirl tower test facility for helicopter rotor system test and evaluation. Design results are summarized and compared with design requirements.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 춘계학술대회 논문집
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• pp.484-489
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• 2011

In this paper, it was described the current technology status of bearingless rotor hub system for helicopter which is one of major rotor hub system. Also, a conceptual study on the new bearingless rotor hub system of helicopter was described. First, the advantages and disadvantages of major helicopter rotor hub system are described in comparison to each other types of rotor hub system. The unique characteristics of bearingless rotor hub system are described compared to other types of rotor hub systems. Next, the main function, role and characteristics of the sub-components of bearingless rotor hub system are described. Recent helicopters which adopt this bearingless rotor hub system are described and introduced. This conceptual study shows that double-H sectional construction and rectangular construction of flexbeam are the most effective candidates of this new bearingless rotor system. This bearingless rotor hub system can be used for 7,000lbs class helicopter. Now, a further trade-off study will show.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2006년도 추계 학술대회논문집
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• pp.151-154
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• 2006

In the present paper, hovering performance analyses of proprotor and helicopter rotor blades were performed by using FLUENT software. As a proprotor, TRAM(Tilt Rotor Aeroacoustic Model) was selected and performance analysis was carried out with mesh adaptation for more elaborate solution. As a helicopter rotor blades, two bladed Caradonna and Tung's rotor and four-bladed BO-105 helicopter rotor blades were selected. In case of Caradonna and Tung's rotor, vortex trajectory was compared with experimental data to inspect the vortex convection capability of the present flow solver. For the final case, performance of BO-105 helicopter rotor blades was investigated and compared with experimental data. After performance analyses of proprotor and helicopter rotors, it was shown that the present solver showed reasonable vortex strength, wake geometry and thurst coefficient distributions. But power coefficient was somewhat overestimated about $10%{\sim}15%$ regard less of mesh adaptation.

• Journal of Biosystems Engineering
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• 제33권2호
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• pp.94-100
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• 2008

Present chemical application method using a power sprayer has been labor intensive, costly and ineffective. Therefore, a small agricultural unmanned helicopter was suggested to replace the conventional spray system. In this study, conceptual design for developing the helicopter and a consequential prototype were reported. The overall conceptual design was initiated by deciding the type of agricultural helicopter, as the single rotor helicopter with a tail system. As the first step of the designing, an air-cooled, 2-stroke engine was selected and a prototype transmission was designed by determining the rotating speed of main rotor shaft. A 'pusher' type tail rotor system was adapted to balance the reaction torque and reduce the power use. The tail boom length was designed to avoid the rotating trajectory of the main rotor. The RF console consisted of the engine control, attitude control, and emergency control modules. Assembling the prototype concluded the mechanical development of the agricultural helicopter.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 춘계학술대회 논문집
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• pp.383-389
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• 2013

Rotor system is a very important part which produces lift, thrust and control force in helicopter. Component of rotor system must endure various flight load for the required life. In helicopter rotor system, bearingless rotor system is the highest technology rotor system compare with articulated and hingeless rotor system. Baaringless rotor system is not include mechanical flap hinge, lag hinge and pitch bearing. Bearingless rotor component flexbeam which made by composite material has conduct hinge and bearing role instead of mechanical flap hinge, lag hinge and pitch bearing. These characteristics has less part number and lass weight than others. In this paper, conduct safe life analysis of bearingless composite component flexbeam and torque tube applying to utility helicopter load condition.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.648-653
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• 2007

In this study, we have generated fatigue load spectrum that is using to prediction of life time for the helicopter rotor blades. We derive utility helicopter missions for the sake of generating load spectrum. Helix and Felix are standard loading sequences which relate to the main rotors of helicopters with articulated and semi-rigid rotors respectively. We got scale factors which is applied to specific case and it did be obtained through the finite element analysis tools. The fatigue life of the rotor blade is estimated by using MSC/Fatigue. We suggest that generated our fatigue load spectrum in conjunction with small utility helicopter should use to rotor blade fatigue test of the korea helicopter program.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.325-329
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• 2003

Nowadays many peoples are using helicopter in various fields, not only military use but also common people applications such as air-measurement, photography, transportation of goods and persons, saving life and fire fighting etc. And it will be expected more popular than now. Most important part of helicopter to increasing performance and to reducing noise is rotor hub-system. Hub system consists of rotor-blade and rotor-hub. We participate to develop next-generation rotor hub system with elastomeric bearing, part of rotor hub. In this paper we introduce about the role and shape of elastomeric bearing in next-generation helicopter hub system. Then we study about bearing-material requirements and measuring methods. Finally we represent some experimental results.

• 소음진동
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• 제10권2호
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• pp.229-239
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• 2000

To reduce the drag rise on the advancing helicopter rotor blade tips, the tip of the blade is modified to have sweep, anhedral and pretwist. The equations of motion of rotor blade with these tip angles were derived using Hamilton principle, programmed using FORTRAN and named as ARMDAS(Advanced Rotorcraft Multidisplinary Design and Analysis System). Rotating frequency analysis of rotor blades with swept tipe was performed that is necessary in conceptual and preliminary design phases of the helicopter design. Vibration analysis of non-rotating blades was also accomplished and compared with MSC/NASTRAN resutls for the basis of comparison with the vibration test data. The rotating frequency analysis of blades with an actual rotor blade data was also performed to verify coded program and to check the possibility of a resonance of an actual rotor blade at the specific rotating speed.

• 한국항공우주학회지
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• 제41권9호
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• pp.726-733
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• 2013

헬리콥터 로터 블레이드는 헬리콥터의 성능을 좌우하는 동시에 비행 시 주된 소음을 발생함에 따라 고성능, 저소음 특성이 요구되는 구상품이다. 국내 소형무장헬기 개발과 병행하여 개발될 민수헬기는 해외체계업체 보유 민수헬기를 기반으로한 국제공동 업그레이드 개발이 추진됨에 따라 해외체계업체 제시 대상기종의 로터 블레이드 성능파악이 매우 중요하다. 본 연구는 해외체계업체 제시 대상기종 블레이드의 성능분석을 통하여 최신 해외 블레이드 대비 성능파악 및 국내고유형상 블레이드 개발 가능성을 타진하는 것을 목적으로 수행되었다. 본 연구의 결과는 일차적으로 향후 민수헬기개발사업의 해외협상 및 국내 고유형상 블레이드 개발 시 목표 성능지표 등으로 활용될 수 있다.