• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.10
• /
• pp.459-467
• /
• 2019

The landing gear is a component that requires a high degree of safety to protect the lives of rotary-wing aircraft and boarding personnel, absorbing the impact on transfer/landing and supporting the fuselage during taxiing and mooring on the ground. In particular, the wheel landing gear supporting the aircraft fuselage absorbs most of the shock from the ground through the shock absorber and tires. This ensures the safety of the pilot on board the aircraft and satisfies the operational capability of the soldiers between missions. During the operation of a rotary-wing aircraft, a number of piston pins, which are a component of the right main wheel landing gear, were found to be broken. Therefore, this study examined the root cause of the piston pin crack phenomenon found in the main wheel landing gear. For this purpose, various causes were identified from fracture surface analysis of a flight test. In particular, the possibility of cracking was analyzed based on the influence on the fastening torque with the drag beam component applied to the piston pin at the time of development. This ensures the fatigue life and structural integrity.

• Journal of Mechanical Science and Technology
• /
• v.14 no.9
• /
• pp.968-977
• /
• 2000

The motion of an aircraft landing gear over a rough runway can be modeled by a nonclassically damped system subject to nonstationary random excitations. In this paper, the approximate analysis methods based on either the real or complex normal modes for the computation of nonstationary response covariances are proposed. It has been found by simulation involving a realistic example that, for the nonclassically damped random vibrational systems, the approximate solution method based on the complex normal mode is superior to other approaches with respect to the accuracy and computation time.

• Transactions of Materials Processing
• /
• v.6 no.4
• /
• pp.291-299
• /
• 1997

This paper is concerned with the design of process sequence to form the inner skin of landing gear. The inner skin of landing gear is a part of airplane which is known to be difficult to form its shape. Our study investigates the production method of inner skin and examines the design criteria by three dimensional elastic-plastic finite element method. Based on the results of simulation, design strategy for improving the process sequence is developed using stretch forming process. The final product of inner skin is produced in multi-stage operations with annealing treatment to meet the required capacity of press. The numerical results show that the newly designed process can produce the required part successfully within the design criteria.

• Journal of Aerospace System Engineering
• /
• v.2 no.1
• /
• pp.1-6
• /
• 2008

In this paper, full body modeling and analysis of nose and main landing gear's characteristics of a helicopter are performed using the dynamics analysis program ADAMS. Also, when land limiting about helicopter body's degree-of-freedom, compared the characteristics. In the case of helicopter, because there are a lot of dangerous missions under flight condition that is disadvantageous than fixed wing airplane, need more detailed research for a helicopter.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.18 no.4
• /
• pp.343-349
• /
• 2015

This is a study for the improvement of the fractured lug structure that connects the landing gear to the fuselage of the aircraft using the composite leaf spring landing gear. The lug surface was analyzed to find out the cause of fracture. The lug was destroyed by the crack initiation and propagation under the repeated stresses. The frictional wears of the lug structure were proceeded and that affected adversely to the crack. Also, the square protrusion of the lug has a weak shape to bring about stress concentration. The design changes were conducted and the test was performed to verify changed design results.

• Journal of Aerospace System Engineering
• /
• v.4 no.3
• /
• pp.34-38
• /
• 2010

ACN(Aircraft Classification Number) is allocated by marketing group during early stage of aircraft design phase and is a critical parameter to decide whether the designed aircraft can be landed or not in a certain airport. The loading on the main landing gear wheels, selection of main landing gear tire and estimation of ACNs for flexible and rigid pavements were done for the proposed medium-class aircraft. The estimated ACN values are compared with the similar class aircraft. And PCN(Pavement Classification Number) values of airport in Korea are surmmarized. Results showed that the currently proposed medium-class aircraft can land any airport in Korea.

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

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.45 no.6
• /
• pp.490-497
• /
• 2017

The Main Landing Gear(MLG) of Rotary Wing Aircraft is an essential equipment in Landing System for pilot to perform a flight mission. It supports the fuselage at ground and absorbs the impact from the ground when landing, thereby, these functions sustain operational capability for pilot and crew. However, the A aircraft caused asymmetry and leakage hydraulic when it was stationed on the ground. Therefore, this paper summarizes pilot comments in operation which are classified by cause of occurrence and the troubleshooting process about each comment. It also describes design improvements which was derived from troubleshooting and suggests verification results of flight test.

• Journal of Aerospace System Engineering
• /
• v.12 no.1
• /
• pp.1-9
• /
• 2018

In this study, a hybrid control method that adjusts for the existing force control technique has been presented for consideration. The proposed hybrid control technique does away with the chattering phenomenon occurring in existing force control technique and provides high shock absorption efficiency. In order to design the controller for the landing gear with MR damper, the equation of motion of the landing gear was derived. The hybrid controller was designed after constructing a simulation model using Recur-Dyne, multi-body dynamic analysis software. The hybrid controller can reduce the maximum strut force and displacement based on the skyhook controller, and is able to get the high efficiency by making it work for the additional force control technique. In addition, an effective switching control technique and input shaping technique was applied to prevent the chattering in the drop simulation. Finally, the performance of the landing characteristics was evaluated throughout the various drop simulations.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.46 no.2
• /
• pp.124-132
• /
• 2018

In this paper, landing stability evaluation of lunar lander considering various landing conditions was performed. The status of landing stability of the lunar lander is classified into stable landing, conditionally stable landing due to sliding and unstable landing due to tip-over. In particular, the quasi-static tip-over equation was rearranged considering the phenomena of lowering the center of gravity and extension of foot-pad interval of the landing gear. These results were compared by finite element model analysis results using a commercial software ABAQUS and its validity and accuracy were verified. The verified finite element model was used for examining the tendency of various environmental variables such as landing conditions, friction coefficient, lateral speed and slope of ground.