• Aerospace Engineering and Technology
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• v.13 no.1
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• pp.27-36
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• 2014

Generally, satellites continuously monitor that its major functions are working properly and their hardware are in a good status using several SOH data. In case a fault that is not recognized as a temporal problem or a failure that can be considered to propagate its damage to the other parts are detected, fault management logic is performed automatically without any contact of ground station. In this paper, attitude error detection using sun sensors on a rotating solar array is proposed. Attitude error can be detected by comparing the offset angle between the actual data computed from the sun sensor and the data predicted from the orbit and ephemeris information for the two types of solar array operation method. During the eclipse, the output of attitude error detection method becomes zero because the sun sensor output cannot be provided. Finally, the proposed method is analyzed through the data processing using on-orbit data.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.5
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• pp.415-422
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• 2014

There has been a lot of discussion to revise military helicopter crashworthiness design criteria. In this paper, newly revised crashworthiness criteria is analyzed centering around the Crashworthiness Index which is the core content of revised criteria. The Crashworthiness Index(CI) was conceived as an adequate method to quantify the crashworthiness capabilities of a rotorcraft design. The index can rate how well a new or derivative design complies with design requirements. The CI rating is made up of seven assessment areas. While the Basic Airframe Crashworthiness(BAC) area tends to be an objective calculation, other areas of the CI tend to be more subjective. Therefore, in this paper, detail CI calculation process for the BAC area is analyzed to inspect the effectiveness of revised criteria.

• Journal of Aerospace System Engineering
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• v.13 no.6
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• pp.52-59
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• 2019

The rotor blade is a key component that generates the lift, thrust, and control forces required for helicopter flight by the torque transmitted through the hub and the blade pitch angle control, and should be designed to factor vibration characteristics so that there is no risk of resonance with structural safety. In this study, the structural design of the main rotor blade for MPUH(Multi-Purpose Unmanned Helicopter) was conducted and the sectional stiffness measurement of the fabricated blade was performed. The evaluation of the vibration characteristics of the main rotor system was then conducted factoring the measured stiffness distribution. The interior of the rotor blade comprised of the skin, spar, and torsion box, and carbon and glass fiber composites were applied. The Ksec2D program was applied to predict the stiffness of blade, and the results were compared to the measured data. CAMRADII, a comprehensive rotorcraft analysis program, was applied to investigate the natural frequency trends and resonance risks due to the rotor rotation.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.10
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• pp.877-886
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• 2016

A validation study is conducted for the conceptual design and performance analysis of UH-60A Black Hawk in order to establish the conceptual design and performance analysis techniques for conventional helicopters using a single main rotor and a tail rotor. As a tool for conceptual design and analysis, NDARC(NASA Design and Analysis of Rotorcraft) is used for the present study. The conceptual design for UH-60A is successfully validated as compared with the target values. Then, various performance analyses in hover and forward flight are conducted for the UH-60A model obtained from the present design work, and they are compared well with the wind tunnel test, flight test, and previous analyses using various analysis tools. Through this validation work, the conceptual design and performance analysis techniques for the conventional helicopter are appropriately established.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.1
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• pp.46-53
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• 2017

This paper shows a length of wirecutter using an analysis based on Rotorcraft's control input and taxiing speed. In case of selecting an inappropriate length of wirecutter which applies to rotorcraft for safety, this causes a collision between blade and wirecuter, or an accident by wire. We review the control input which was used in development stage, and establish the conditions of control input which are needed in taxiing. Based on these conditions, we review the collision possibility between blade and wirecutter through analysis in case of 20, 40, 60 kts taxiing speed. Following, this result is verified by comparison with that of a simulation test in rotorcarft. Finally, in case of high collision possibility, we presented the downsize length to avoid the collision and increment of non-protective area in flight, simultaneously.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.5
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• pp.514-523
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• 2008

This paper presents a single-axis simulator developed to verify the attitude control algorithm of KAUSAT-2 satellite. Named KAUSatSIM, the simulator is composed of a single-axis rotation table using an air-bearing that simulates a frictionless environment, as well as sensors and momentum wheel that was used on KAUSAT-2. The simulator can be utilized for verification of KAUSAT-2 attitude control algorithm, development of new algorithms, and verification of performance. Tests were performed on the single-axis rotation simulator using the momentum wheel in order to verify the attitude control algorithm of KAUSAT-2. Satisfactory test results were obtained by designing a wheel controller that employs the proportional-derivative control method. In addition, a propulsion system was added and tested for development of a new satellite attitude control algorithm.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.3
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• pp.217-225
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• 2013

Typical quadrotor aircraft use four differential thrust vectors to control the motion. In this study, we design a quadrotor aircraft using collective and cyclic control to improve the shortcomings of existing quadrotor aircraft. The quadrotor aircraft with cyclic control can fly at various attitudes due to the excessive control degrees of freedom. Hence the quadrotor aircraft with cyclic control is suitable as high performance aircraft. In this study, modeling and stability analysis of the quadrotor aircraft have been performed using FLIGHTLAB. LQR control systems were designed using linear models at various flight conditions and verified through nonlinear simulations using MATLAB.

• 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.46 no.1
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• pp.59-67
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• 2018

In this paper, the test facility for coaxial propellers at low Reynolds developed and validated by measured data. The test equipment was designed to measure the hovering performance of propellers according to distances between the upper/lower propellers. Thrust, torque, rotational speed, vibration, and amperage of upper and lower propellers can be measured separately. The data acquisition system was built to collect signals of sensors, and LabVIEW software was used to control the motor and collect the signal. The hover performance tests of single propellers were preceded for the facility validation, and then the performance values of coaxial propellers were measured according to distances and diameter differences between the upper/lower propellers. The results showed that the high efficiency is achieved at 20%~30% distance between the upper propeller and lower one. The configuration that the upper propeller has shorter diameter than the lower one has the highest efficiency than other configuration.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.6
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• pp.452-463
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• 2018

Tip-jet gyroplane is a type of compound helicopter that employs the tip-jet system to rotate the rotor by a reaction force from the gas jetted at the rotor tips in hovering. In forward flight, tip-jet gyroplane converts into a form of a gyroplane. Therefore, it is necessary to develop a new conceptual design method to consider three flight modes: tip-jet mode, gyroplane mode, and transient mode. This study developed the numerical code of conceptual design methodology that can consider three flight modes. The developed code was validated against the available experiment data. Based on the developed code, initial sizing of tip-jet gyroplane was performed for two mission profiles including high speed forward flight of 150knots with a mission range of 300km or 400km. Subsequently, the configuration and performance of the 3,000lb tip-jet gyroplane were analyzed.