• Journal of Aerospace System Engineering
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• v.14 no.1
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• pp.28-35
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• 2020

This paper presents the design improvements made for the crack which is in the mounting structure of the mechanical structure of rotary wing aircraft. The doubler added to the mounting structure of rotary wing aircraft was designed and manufactured based on the load at the development stage, and a crack was found in the surface of doubler at a certain point during the operation of the aircraft. To identify the cause of the crack, the initial deformation of the structure, which may occur as a result of fastening condition, was considered and the dynamic analysis of the natural frequency of the structure comparing to the blade passing frequency of the aircraft were additionally reviewed. As a result of this study, a shim was added to remove the physical gap of the fastening area, and a doubler with thickened reinforcement was installed. The increase of structural strength is shown by reviewing the results of dynamic analysis for the structural verification of the improved design, and the fatigue evaluation complied to the requirement of the aircraft lifetime.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.10
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• pp.459-467
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• 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 the Korean Society for Aeronautical & Space Sciences
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• v.41 no.1
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• pp.31-39
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• 2013

A Quad Tilt Wing UAV is a new concept hybrid UAV having the advantages of both fixed-wing and rotary-wing aircraft. This paper presents longitudinal flight dynamic characteristics of a Quad Tilt Wing UAV. The designed Quad Tilt Wing UAV is a configuration of a tandem wing type aircraft with an actuating motor and propeller mounted at each wing. Momentum theory is used to calculate the thrust, and nonlinear modeling is performed considering lift and drag generated by slip stream effect of propellers. Also, Force and moment variation at each tilting angle is considered. Static trim on longitudinal axis is analyzed via numerical simulation. Componentwise force contribution was analyzed at each trim mode. Dynamic characteristics were evaluated through eigenvalue analysis for a linear model at each flight mode. It is verified that longitudinal dynamic characteristics are changing from unstable to stable state by continuous transition of dominant poles.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.16 no.1
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• pp.29-36
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• 2008

The vulnerability of aircraft, especially rotary wing aircraft, has been an ongoing issue since their advent in combat operations during the 1940s. In this paper, representative sensors for survivability of those aircraft in modern battlefield are surveyed and top level requirements and parameters are defined. Also problems of multi-sensor alignment on modern agile and flexible platform are discussed and several techniques such as static alignment and transfer alignment are introduced.

• Journal of Drive and Control
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• v.14 no.2
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• pp.37-44
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• 2017

In this study, in order to prevent cavitation in a variable swash-plate type hydraulic pump, a basic model impeller has been applied to a new pump, and the impeller shape has been optimized through flow analysis. Based on the analysis results, we could propose an impeller shape with high efficiency and low possibility of cavitation in comparison with the basic model. The simplification of the basic shape of the impeller of the hydraulic pump was performed in three parts in the order of hub shape, wing, and curvature, and eight design parameters were defined to satisfy the design requirement. Compared with the initial model of the impeller, when the differential pressure of the optimum model increased, the efficiency was improved. It achieved the goal of design improvement because cavitation did not occur under the rated operating conditions.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.30 no.1
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• pp.38-43
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• 2022

As the use of unmanned aerial vehicles increases, in order to expand the operability of the unmanned aerial vehicle, it is essential to develop an unmanned aerial vehicle traffic management system, and to establish the system, it is necessary to analyze the integrated navigation performance of the unmanned aerial vehicle to be operated. Integrated navigation performance is affected by various factors such as the type of unmanned aerial vehicle, flight environment, and guidance law algorithm. In addition, since a large amount of flight data is required to obtain high-reliability analysis results, efficient and consistent flight scenarios are required. In this paper, a flight scenario that satisfies the requirements for integrated navigation performance analysis of rotary and fixed-wing unmanned aerial vehicles was designed and verified through flight experiments.

• Journal of Aerospace System Engineering
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• v.15 no.5
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• pp.16-23
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• 2021

Domestic and foreign manufacturers are developing VTOL UASs in various shapes in line with demand for future technologies. UASs have been developed in a shape classified as fixed/rotary wing, and verified by appropriate certification standards. However, airworthiness certification of recent VTOL UASs is strict with the absence of VTOL-specific certification standards. In this paper, criteria applicable to VTOL UAS were presented through analysis of STANAG-4671 and STANAG-4702, which are certification standards for fixed/rotary wing UAS of the North Atlantic Treaty Organization (NATO) and the Special Condition for VTOL Aircraft (SC-VTOL) of European Aviation Safety Agency (EASA). For this, the categorization criteria of general/fixed-wing/VTOL characteristics were established for each standard item and utilized for analysis.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.5
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• pp.969-974
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• 2021

South Korea is making efforts to select a drone industry, a type of unmanned aerial vehicle, as one of the 7 major industries in the country, to select a drone-specific liberalization zone and to establish and revise a drone-related bill. Through these efforts, drone delivery and drone taxis are expected to be operated in the future. Therefore, a multilateral collision avoidance system with existing aircraft such as drones, fixed-wing and rotary-wing should be established to prepare for possible drone and air-borne collisions.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.6
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• pp.490-497
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• 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 the Korean Society for Aeronautical & Space Sciences
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• v.41 no.9
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• pp.734-739
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• 2013

Representative crashworthiness requirement documents for military helicopter are MIL-STD-1290 and the Aircraft Crash Survival Design Guide(ACSDG) which were lastly revised in the 1980's. Taking analysis results of diverse U.S. Army helicopter mishaps into account, we can say that adequate guidelines do not exist to ensure crashworthiness of new generation aircraft. In this paper, U.S. Army helicopter mishap analysis conducted by U.S. Army Research, Development and Engineering Command(RDECOM) is readjusted to review the basis of new crashworthiness design criteria for military helicopter, in other words, Full Spectrum Crashworthiness Criteria(FSCC). This analysis effort is a part of FSC development. This effort was to research and quantify the dynamics of military aircraft crashes to be used as the quantitative basis for new design criteria.