• Journal of Aerospace System Engineering
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• v.12 no.2
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• pp.59-65
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• 2018

The landing gear (L/G) handle of an aircraft is an essential piece of equipment for aircraft take-off and landing. The bracket in the landing gear handle was fractured during a vibration test when developing the landing gear handle. This paper summarizes the vibration test procedures performed during landing gear handle development. A cause analysis, design improvements, and verification results of the fault in the vibration test are also provided.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.480-483
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• 2010

착륙장치는 완충장치를 이용하여 항공기 착륙 시의 충격을 흡수하는 역할을 한다. 여러 방식의 완충장치가 있으나, Oil에 의한 감쇠력과 Gas에 의한 스프링력을 이용하여 에너지를 흡수하는 유공압 방식이 가장널리 사용되고 있다. 착륙장치 성능해석에서는 다양한 착륙조건에 대한 Dynamic simulation을 통해 최적의 Orifice 형상과 Gas spring 특성을 결정하고, 설계에 필요한 착륙하중을 구하게 된다. 이 논문에서는 상용 프로그램인 VI-Aircraft를 이용한 착륙장치 성능해석 과정을 소개한다. 유공압 완충장치의 모델링 및 Landing simulation 결과를 분석하고, 이에 따른 완충효율 최적화 과정을 제시한다.

• Proceedings of the KAIS Fall Conference
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• 2011.12b
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• pp.507-510
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• 2011

착륙장치는 완충장치를 이용하여 항공기 착륙 시의 충격을 흡수하는 역할을 한다. 군용 헬기를 비롯한 일부 항공기에서는 비상 착륙시 탑승원의 생존성과 안전성을 향상시키기 위해, 착륙장치에 내추락 요구조건을 부여하기도 한다. 본 연구에서는 내추락 요구조건을 충족하는 다양한 착륙장치 설계 개념 가운데, 파손 장치를 이용한 전륜 착륙장치와 Blow-off 밸브를 이용한 주륜 착륙장치 설계를 제시하고, 성능해석을 통한 입증 과정을 소개한다.

• Aerospace Engineering and Technology
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• v.3 no.2
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• pp.191-196
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• 2004

Most of studies for landing gear have been performed to analyze the shock absorbing characteristics of oleo-pneumatic struts. But it is not easy to solve the dynamic specific properties of spring type composite landing gear using a present method. The shock absorbing abilities of oleo-pneumatic landing gear strut are under influence of the internal design method on the strut rather than the landing gear structure itself. Unlike oleo type, spring type composite strut absorbs the shock with structural strength and dynamic characteristics of the strut's material and shape. The tests and analysis for the shock absorbing rate and dynamic behavior of the spring type composite fixed landing gear for 4 seats small aircraft, have been performed using landing gear drop test rig.

• Proceedings of the KAIS Fall Conference
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• 2011.12b
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• pp.503-506
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• 2011

항공기 착륙장치 피로 수명평가에는 안전 수명방법이 사용된다. 안전 수명방법은 항공기 전 수명기간을 모사하는 피로하중 스펙트럼 조건에서 균열 또는 유해한 변형과 같은 구조적 결함이 발생하지 않도록 설계/입증하는 것을 말한다. 설계 단계에서는 해석적 방법을 통해 착륙 및 지상운용하중을 구하고, 이를 착륙장치 피로해석에 적용하여 피로수명을 확인한다. 착륙장치는 수명 기간 중 일반적으로 High Cycle 피로를 겪게 되므로, 피로해석 시 응력 기반의 접근 방법이 적용된다. 시험평가 단계에서는 일반적으로 4배의 운용수명에 해당하는 피로하중 스펙트럼에 대해 시험을 수행하여, 착륙장치의 안전 수명을 최종 입증하게 된다. 이와 같이 항공기 착륙장치 피로 수명평가를 위해서는 착륙 및 지상운용 하중해석에서부터 피로해석, 피로시험에 이르기까지 전 과정이 유기적으로 결합되어 이루어져야 한다. 본 연구에서는 항공기 착륙장치 피로시험에 필요한 세부과정과 관련 기술을 실제 적용 사례와 함께 기술하였다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.7
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• pp.601-607
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• 2012

The main function of a landing gear is to absorb the impact energy during touchdown. It it occasionally required for landing gear to have crashworthiness for improving survivability and safety in case of emergency landing. This paper introduces the design concept, performance analysis and drop test procedures for the development of the crashworthy landing gear. The shock absorbing ability and the crash behavior are proved by analyzing various sensor data and video clips from high speed camera recording during drop tests.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.1
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• pp.91-96
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• 2012

The retract actuator makes the landing gear retract or extend during take-off and landing of an aircraft. To prevent folding of landing gear that has remained in the extended state because of an unexpected external disturbance, an internal locking device is applied to the retract actuator. The locking device is restrained with another internal component by oil pressure supplied to the retract actuator, and this restraint makes the locking of the actuator possible. Because locking and unlocking are repeated during retraction and extension of the landing gear, the locking device takes repeated identical loads, and the possibility of fatigue failure exists. In this study, the process and results of fatigue analysis for the locking device are presented, and the appropriateness of the analysis result is verified using a fatigue test.

• Current Industrial and Technological Trends in Aerospace
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• v.9 no.1
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• pp.119-129
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• 2011

The soft landing of a lunar lander after the entrance of lunar orbit is an essential prerequisite for the accomplishment of the lander's lunar mission. During the landing process of a lunar lander, efficient shock absorption and stability maintenance are indispensible technology to protect payloads. Therefore, the landing gear is a crucial structural component of a lunar lander, it has to absorb the kinetic energy associated with touchdown and support the static load of the landing module in an upright position. In this paper, various landing gears of lunar landers which are being developed as well as which had been successfully landed on the moon surface are investigated. In the end, the Korean lunar lander, which is being designed for preliminary development model, is presented as an example of the lunar lander development.

• Aerospace Engineering and Technology
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• v.4 no.2
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• pp.15-20
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• 2005

Most of studies for the ground load and ground behavior of landing gear have been conducted with an assumption that the structure of landing gear was rigid body. The assumption of rigid body during design process results in many errors or discrepancy. High ground load occurs in 3 directions on the shock absorbing strut during landing. This ground load initiated high structural deformation. In this study, the flex-multi-body dynamics is applied to adapt flexible bodies, so the results of analysis can be described close to landing gears real behaviour.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.6
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• pp.110-117
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• 2003

The operational characteristics of the landing gear retraction/extension depend on the complexity of design variables operational/environmental conditions. In order to meet the requirements of minimum stow area and performance, the integration of the landing gear system requires operational kinematic and dynamic analysis considering an effect of its related system. This study investigates operational dynamic behaviors of the T-50 landing gear system using ADAMS. Taking into account for various operational/environmental conditions, an analysis of dynamic behavior on the landing gear operational characteristics is performed with experience derived from a wide range of proprietary designs. Analytical results are presented for discussing the effects of temperature, aerodynamic and maneuver load on normal/emergency operation of the landing gears and doors. This analysis leads us to the conclusion that the proposed program is shown to be a better quantitative one that apply to a new development and troubleshooting of the landing gear system.