• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.5
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• pp.58-64
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• 2004

A new method to obtain approximate solutions by placing the only poles of the slow subsystem for the two-time-scale aircraft dynamic systems. The two kinds of approximate solutions are obtained by a matrix block diagonalization. One is called the uncorrected solution, and the other is called the corrected solution. The former has an error of $O({\varepsilon})$, and the latter has an error of $O({\varepsilon}^2)$. Of course, both solutions are robust enough even though they are reduced solutions. The excellence of the proposed method is illustrated by an numerical example of an aircraft longitudinal dynamics.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.6
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• pp.512-519
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• 2016

Auxiliary Power Unit of FA-50 which provides energy other than propulsion is an important element to maintain airworthiness on aircraft. Also Inlet Guide Vane of Auxiliary Power Unit is a device that supplies appropriate airflow into the Auxiliary Power Unit after adjusting influent airflow into the load compressor. This report, based on the problems occurred the driving gears of Inlet Guide Vane, deals with cause of occurrence, troubleshooting, design improvement and result of test flight verification for FA-50 aircraft Auxiliary Power Unit lifespan.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.3
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• pp.39-49
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• 2003

The delta operator approach and the singular perturbation technique are introduced. The former reduces the round-off error in the numerical computation. The latter reduces computing time by decoupling the original system into the fast and slow sub-systems. The aircraft dynamics consists of the Phugoid and short-period motions whether its model is longitudinal or lateral. In this paper, an approximated solutions of lateral dynamic model of Beaver obtained by using those two methods in compared with the exact solution. For open-loop system and closed-loop system, and approximated solution gets identical to the exact solution with only one iteration and without iteration, respectively. Therefore, it is shown that implementing those approaches is very effective in the flight dynamic and control.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.4 no.1
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• pp.25-38
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• 1996

본 연구에서는 항공기 사고의 70%이상을 차지하는 이 ${\cdot}$ 착륙단계 중에서, 이륙 직후 저고도에서 동력이 상실되었을 경우에 이륙활주로 방향으로 Turning Back하는 것은 어떠한 안전 한계를 지니고 있는지를 알아보기 위하여, 우선 조종사에 대한 설문 조사를 실시하여 비행 경력별로 이륙 직후 동력 상실시의 비상 처치 경향과 위험에 처할 확률을 조사하였다. 그리고 실제 활공 성능이 우수한 M20J 항공기와 기동 성능이 우수한 FH20 항공기를 이용한 비행 시험을 통하여 이륙 직후 Turning Back to Runway조작 시의 고도 손실과 선회시 하강율을 실험 자료로 구하였다. 비행 시험 자료를 비교 적용함은 물론 선회 소요 시간과 고도 손실, 선회율과 활공 속도와의 관계 등의 항공 역학적 이론을 적용한 분석 근거에 기초하여 안전하게 Turning Back to Runway 조작을 시작할 수 있는 안전 고도 한계 및 선회율을 제시하였다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.5
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• pp.391-403
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• 2013

Propeller aircraft propelled by an electric propulsion system is gaining a renewed interest because of ever-increasing environmental concern on harmful emissions emitted from conventional jet engines and national energy security. Traditional aircraft sizing methods are not readily applicable to electric propulsion aircraft that utilize a variety of alternative energy sources and power generation systems. This study showcases an electric propulsion aircraft sizing exercise based on a generalized, power based sizing method. A general aviation aircraft is propelled by an electric propulsion system that comprises of a propeller, a high temperature super conducting motor, a Proton Exchange Membrance(PEM) fuel cell system fuelled with hydrogen, and power conditioning equipment. In order to assess the impact of technology progression, aircraft sizing was conducted for two different sets of technology assumptions for electric components, and the results were compared with conventional baseline aircraft.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.12
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• pp.969-976
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• 2020

Urban Air Mobility is attracting attention as a future innovation industry around the world, and leading industries are considering the application of composite materials for structural robustness and lightening in the designing and manufacturing new concept eVTOL aircraft. To apply composite materials to the new concept of eVTO aircraft, this paper was analyzed about composite material qualification system of FAA & EASA and institutionalized by Korea Government, including the procedures and methods, the organization to carry out the material verification for domestic conditions. The domestic composite material qualification system will not only make it easier for manufacturers of eVTOL aircraft with a new concept to apply composite materials to domestic aircraft through pre-material qualification, but also reduce the burden of material qualification within the period of type certification. In addition, domestic manufacturers of composite materials with qualified material quality and performance will be easy to enter for domestic aircraft applications and composite material manufacturers with experience in applying to aircraft will have a positive impact on overseas exports. This system will be able to promote the development eVTOL aircraft industry of a new concept and enhance international credibility of made aircraft in Korea.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.6
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• pp.523-535
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• 2012

Solar powered aircraft are becoming more and more interesting for future long endurance missions at hight altitudes, because they could provide surveillance, earth monitoring, telecommunications, etc. without any atmospheric pollution and hopefully in the near future with competitive costs compared with satellites. However, traditional aircraft sizing methods currently employed in the conceptual design phase are not immediately applicable to solar powered aircraft. Hence, energy balance and constraint analyses were performed to determine how various power system components effect the sizing of a solar powered long endurance aircraft. The primary power system components considered in this study were photovoltaic (PV) modules for power generation and regenerative fuel cells for energy storage. To verify current research results, these new sizing methods were applied to HALE aircraft and results were presented.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.7
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• pp.590-600
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• 2012

In this research, generalized sizing methods were studied that can be applied to an aircraft which uses solar cell or fuel cell as energy sources. To consider multiple propulsion systems and energy resources, multiple power paths were modeled and the weight of consumable and non-consumable energy was reflected in the weight change calculation for each mission segments. In the constraint analysis, power to weight ratio was selected instead of thrust to weight ratio and used in the sizing process of balancing power and energy.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.21 no.4
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• pp.41-46
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• 2013

This paper deals with an experimental technique for the measurement of dynamic stability derivatives in the roll motion of aircraft. Experimental aquisition method for aircraft's dynamic stability derivatives is conducted on the oscillation condition of aircraft model in the subsonic wind tunnel. The oscillation of aircraft model was forced by the oscillation apparatus. The forced oscillation technique is the method getting data from the internal balance inserted into the aircraft model during oscillating it. Dynamic stability derivatives of rolling motion were calculated by data reduction from the measurements of rolling moment, frequency and amplitude of aircraft model due to forced oscillation under wind conditions. Results of experiment is obtained similar one with those of roll dynamic stability derivatives measured in other institutes.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.7
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• pp.593-599
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• 2021

The demand for e-VTOL aircraft is expected to be increased rapidly in the future as a means of urban transportation due to operating cost reduction, eco-friendliness and convenience of vertical take-off and landing using pilot-aids automation system. However, there are many technical hurdles to be solved in securing safety and certification which are essential for commercialization and urban operation. So far, there is no e-VTOL aircraft that has received type certificate and standard airworthiness certificate due to the technical problems and safety requirement differences with conventional aircraft. The e-VTOL aircraft certification should also meet the equivalent level of safety required by the current airworthiness standards, but there are existing problems in securing safety and meeting current standards. In this study, the e-VTOL's certification problems and technical limitations in satisfying the current standards are presented.