• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.9
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• pp.726-733
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• 2013

The rotor blade of helicopter is the core component determining helicopter performance and requiring low noise and low vibration because the blade becomes the major source of noise during flight. The performance analysis of candidates rotor blades is very critical because LCH(Light Civil Helicopter) will be developed parallel with LAH(Light Armed Helicopter) as an international upgrade program based on the existing platform of foreign civil helicopter. This research was aimed to recognize the performance of the candidates rotor blades compared with the newly developed foreign rotor blades and to investigate the feasibility about developing korea unique shape rotor blades by analysis the rotor performance and noise. The result of this research can be used for the target performance index during negotiation with foreign helicopter company and developing korea unique shape rotor blades.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.2
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• pp.141-149
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• 2018

This paper presents a neural network controller design for complex damage to a blended wing Unmanned Aerial Vehicle(UAV): partial loss of main wing and vertical tail. Longitudinal/lateral axis instability and the change of flight dynamics is investigated via numerical simulation. Based on this, neural network based adaptive controller combined with two types of feedback linearization are designed in order to compensate for the complex damage. Performance of two kinds of dynamic inversion controllers is analyzed against complex damage. According to the structure of the dynamic inversion controller, the performance difference is confirmed in normal situation and under damaged situation. Numerical simulation verifies that the instability from the complex damage of the UAV can be stabilized via the proposed adaptive controller.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.12
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• pp.1143-1150
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• 2007

The fuel transfer characteristics of the jet pump between fuel tanks, which is applied in the smart UAV fuel supply system, were experimentally investigated. The operating conditions of the jet pump were setup to meet the engine requirement according to mission profile, and the jet pump performance was evaluated at those conditions. The pressure ratio and the efficiency of the jet pump were measured with the variation of flow ratio. In addition, the area ratio was taken into the consideration to examine the effect on the jet pump performance. From the evaluation results, the jet pump met the fundamental requirement to transfer fuel with the flow ratio of 2.23. In the case of the jet pump that is focused on the fuel transfer quantity rather than its efficiency, the flow ratio would be adjusted through the variation of area ratio of the jet pump within the permitted limit of pressure ratio.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.4
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• pp.80-87
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• 2004

To understand the each performance parameter correlation of flight type liquid-propellant rocket engine for KSR-III(Korea Sounding Rocket-III), the analysis of engine stand-alone combustion test results was carried out. Considering the variation of ablative material combustion chamber caused by erosion, linear regression analysis that ignores oxidizer/fuel ratio effect and two-variable 2nd-order polynomial regression analysis that considers oxidizer/fuel ratio change were performed. It can be described that linear regression analysis is simple and very practical method, and can predict the performance within 1% error inside analyzed region. And two-variable 2nd-order polynomial regression analysis can predict with very high accuracy inside region and shows that KSR-III engine's optimum oxidizer/fuel ratio for thrust(or specific impulse) is 2.22 and that for combustion chamber pressure(or characteristic velocity) is 2.17.

• 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.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.7
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• pp.655-660
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• 2007

A canard-leading edge flap deflection scheduling laws have been established to enhance the maneuverability of the canard type fighter class aircraft. These scheduling laws are the relation of canard-leading edge flap deflections and flight conditions to maximize the lift-drag ratio. For these purposes, the corrected supersonic panel method has been used to predict the lift-drag characteristics due to canard-leading edge flap deflections. In addition, the high speed wind tunnel test has been conducted with 1/20 scale model to validate the predicted scheduling laws. Good agreements have been obtained compared with the results of high speed wind tunnel test. Based on the results obtained from the experimental and numerical studies, the corrected supersonic panel method has shown to be useful to establish the canard-leading edge flap deflection scheduling law for the aerodynamic design of canard type fighter class aircraft.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.12
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• pp.1031-1038
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• 2017

In order to improve the performance of the air breathing engines, it is important to maximize the total pressure recovery through air intake. In this study, we investigated whether the Oswatitsch method, which guarantees the maximum pressure recovery for supersonic intake, is effective at hypersonic speed by compressing the intake air with the same intensity at each ramp. The non-linearity of the shock wave normal Mach number at each ramp stage was analyzed by comparing the compression ramp angle and the number of ramp to the inflow Mach number in terms of compressible thermodynamics and the operation limits of the inlet. Based on this analysis, the Oswaitisch technique yields valid conditions not only in supersonic but also hypersonic flight regime.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.5
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• pp.623-629
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• 2020

This study examined the airflow field around a gun port on the flight condition of gunfire to verify the aircraft performance and safety effects and gun gas rate, path according to the options of diverter configuration. The gun port diverter not only effectively lowered the heat generated by gunfire but also effectively discharged the gun gas upwards. The path of gun gas can be changed according to its configuration. According to the optional configuration of the rear-gun-port diverter, the flow rate, path, and pressure of the gun gas were analyzed during gunfire. An analysis of the internal velocity distribution and the temperature change of the gun port revealed a rapid decrease in flow rate through the rear diverter according to the option configuration. The forward flow rate showed a similar tendency with little change. This ensures that the gun gas generated during gunfire has a sufficient flow distance from the aircraft surface, regardless of the rear gun port diverter's optional configuration. The flow stagnation of gun gas according to the option configuration of diverter had a great influence on the internal temperature rise of a gun port.

• Journal of the Korean Society of Propulsion Engineers
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• v.3 no.4
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• pp.75-82
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• 1999

Theoretical analysis and performance test of Jet vane type Thrust Vector Control(TVC) were conducted using supersonic cold-flow system. The use of TVC Systems an in particular jet vanes, are currently being researched for use in air launch, ship launch, underwater launch and high altitude maneuvering of tactical missiles and rockets. The necessity to generate control forces to rapidly change the course of the missile is frequently required when traditional, exterior aerodynamic surfaces are unable to produce these forces, when the flow over the control surface is insufficient. This situation can occur at launch, or high angles of attack of the control surfaces. Jet vanes peformed well at all altitudes and environmental conditions, and jet vanes are extremely effective at deflection angles up to as high as $30^{\circ}$, make them ideal for the launch and maneuver applications. In this study, performance test of supersonic cold-flow system and visualization of supersonic jet was conducted, and shape and deflection angle effect of two types of jet vanes are investigated.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.501-504
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• 2011

In this study, structural design of the propeller blade for turboprop aircraft was performed. The propeller shall have high strength to get the thrust to fly at high speed. The high stiffness and strength carbon/epoxy composite material was used for the major structure and skin-spar-foam sandwich structural type was adopted for improvement of lightness. As a design procedure for the present study, firstly the structural design load was estimated through investigation on aerodynamic load and then flanges of spars from major bending loads and the skin from shear loads were preliminarily sized using the netting rule. In order to investigate the structural safety and stability, stress analysis was performed by finite element analysis code MSC. NASTRAN. Finally, it is investigated that designed blade have high efficiency and structural safety to analyze of aerodynamic and structural design results.