• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.15 no.4
• /
• pp.33-37
• /
• 2007

In this paper, a dynamic analysis of a helicopter landing gear with considering flexible structural modes has been investigated. The main body of the helicopter has been modeled as a flexible body using FEM code, then a few selected vibration modes of the helicopter main body have been used as basis for the dynamic analysis of the helicopter landing gear. The simulation of dynamic analysis was carried out on the base of ADAMS aircraft module. It has been found by a series of simulation that the flexible structural modes has a significant effect on the dynamic characteristics of helicopter landing gear as the flexibility of the main body is increased.

• Journal of Institute of Control, Robotics and Systems
• /
• v.15 no.1
• /
• pp.54-60
• /
• 2009

In this paper, a precision landing approach is implemented based on real-time image processing. A full-scale landmark for automatic landing is used. canny edge detection method is applied to identify the outside quadrilateral while circular hough transform is used for the recognition of inside circle. Position information on the ground landmark is uplinked to the unmanned helicopter via ground control computer in real time so that the unmanned helicopter control the air vehicle for accurate landing approach. Ground test and a couple of flight tests for autonomous landing approach show that the image processing and automatic landing operation system have good performance for the landing approach phase at the altitude of $20m{\sim}1m$ above ground level.

• 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 Korean Society for Aeronautical & Space Sciences
• /
• v.34 no.8
• /
• pp.87-94
• /
• 2006

In this study, nonlinear crash analyses have been conducted for the skid landing gear of a helicopter. The realistic landing gear model of the commercial helicopter (SB427) is considered. Three-dimensional dynamic finite element model with variable thickness and material plastic behavior is constructed and LS-DYNA(Ver.970) is used to conduct nonlinear transient crash analyses for different impact conditions. Characteristics of nonlinear transient responses due to the ground crash are investigated for typical structural design criteria of a skid landing gear system. In addition, comparison results for maximum crash deformations of the skid landing gear are presented and the important effect of ground friction for numerical accuracy is described.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.11 no.5
• /
• pp.12-22
• /
• 2008

In this study, the dynamic characteristics for the wheel-type landing gear system of helicopter have been analyzed. Nonlinear multi-body dynamic models of the landing gear system are constructed and the equations of motion, kinematics and internal forces of shock strut are considered. In addition, flexibility effect of the wheel axle with equivalent beam element is taken into account. General purpose commercial finite code, SAMCEF which includes MECANO module is applied. The results of dynamic simulation for various landing and weight conditions are presented and compared with each other. Based on the results, characteristics of impact dynamic behaviors of the landing gear system are practically investigated.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.36 no.4
• /
• pp.346-351
• /
• 2008

In this paper, the semi-active control of a helicopter landing gear using magneto -rheological(MR) damper is studied. A dynamic model of the MR damper is formulated by incorporating magnetic field-dependent Bingham properties of the MR fluid. The electromagnet of the MR damper is designed and its magnetic field is analyzed using a commercial finite element code. The damping characteristics of MR damper by changing the intensity of the magnetic field are investigated and the dynamic responses of the helicopter landing gear with MR damper are simulated. The semi-active control of the helicopter landing gear is simulated by implementing a sky-kook control algorithm and its performance is evaluated comparing to the passive control.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.15 no.6
• /
• pp.746-753
• /
• 2012

ROK military helicopters are frequently exposed to the hazard situations due to the characteristic of operation. Especially, helicopter accident may lead to critical damage of human and structure. Accordingly, pilots have to train the autorotation procedures and learn the skill to prevent hard landing. In this paper, the behavior of skid gear subject to the helicopter autorotation was conducted by using numerical method. The computer simulation approach by using finite element method was employed to accomplish this goal. Additionally, the behavior of skid gear was evaluated for the different landing conditions. In conclusion, the maximum stress concentration was occurred at the attached area of skid cross-tube to the fuselage. Also, it was revealed that the most proper attitude was level landing to prevent hard landing.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2014.05a
• /
• pp.338-340
• /
• 2014

The purpose of this research is to support decision making of emergency rescue system with GIS which selects landing point of emergency rescue for emergency situation on mountains and dropping point when landing is impossible. The area of research was limited to Pocheon-si, Gyeonggi-do. The results were divided into two values; landing point of helicopter on mountains and dropping point. Digital map, forest type map and forest soil map were utilized as fundamental data. Factors of landing point were slope, topographical characteristics, vegetation characteristics and area of helicopter landing point by helicopter data. And, for dropping point, slope and vegetation characteristics were divided as factors and GIS intersect function was utilized for the analysis. But, this research was conducted by excluding factor values of wind direction, wind velocity, etc. In the future, it's necessary to improve effectiveness of the analysis more by making a connection with Meteorological Agency DB.

• Journal of Aerospace System Engineering
• /
• v.8 no.3
• /
• pp.14-19
• /
• 2014

When a helicopter lands on a ship deck in high sea states, one of main difficulties is the ship motion by sea wave, In case of a manned helicopter, a pilot lands a helicopter on the deck during quiescent period of ship motion, which is perceived from different visual cues around landing spot. The capability to predict this quiescent period is very important especially for shipboard recovery of VTOL UAV in harsh environments. This paper describes how to predict heave motion of a ship for shipboard landing of a VTOL UAV. For simulation, ship motion by sea wave was generated using a 4,000 ton class US destroyer model. Heave motion of ship deck was predicted by applying auto-regression method to generated time series data of ship motion.

• Aerospace Engineering and Technology
• /
• v.12 no.1
• /
• pp.10-21
• /
• 2013

As helicopter technology has been upgraded, today its oceanic operation is considered to be usual. In oceanic operation of helicopter, the effect of severe wind, wave, and corrosion must be investigated and the operation procedures for safety as well as the motion of shipboard arising from maneuvers of ship must also be considered. In this paper, it describes the result of trade-off study for shipboard landing and its operation procedure including dynamic interface between ship and aircraft in ship operation and gives a simulation results to implement the oceanic operation of tilt rotor aircraft.