• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.5
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• pp.390-396
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• 2007

In the present study, we have developed a flapping wing using a smart material to mimic the nature's flyers, birds. The wing consists of composite frames, a flexible PVC film and a surface actuator, and the main wing motions are flapping, twisting and camber motions. To change the camber, a Macro-Fiber Composite(MFC) is used as the surface actuator, and it's structural response is analyzed by the use of piezoelectric-thermal analogy. To measure the lift and thrust simultaneously, a test stand consisting of two load cells is manufactured. Some aerodynamic tests are performed for the wing in a subsonic wind tunnel to evaluate the dynamic characteristics. Experimental results show that the main lift is mostly affected by the forward velocity and the pitch angle, but the thrust is mostly affected by the flapping frequency. The effect of the camber generated by the MFC actuator can produce the sufficient lift increment of up to 24.4% in static condition and 20.8% in dynamic condition.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.3
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• pp.226-232
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• 2017

Surface pressure distributions over the RAE-A wing-body configuration were investigated and the grid convergence along the streamwise, spanwise, and circumferential directions was numerically studied. Flow analysis in subsonic and transonic conditions was conducted using the $k-{\omega}$ Wilcox-Durbin+ turbulence model. Surface pressure distributions for subsonic flows were well matched, but those for transonic shocked flows showed a little discrepancy with the experimental data. A cubic spline extrapolation method was applied in order to investigate the grid convergence. This method presented that the grid resolution in the circumferential direction is the most important grid parameter. A refined grid system was made based on the grid convergence study and provided more accurate prediction, especially on the symmetric body surface of RAE-A configuration.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.7
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• pp.574-580
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• 2017

Static dischargers should be installed on air vehicle to emit a static electricity during flight. Especially, If static electricity is not removed by static discharger on the air vehicle, it makes ionization and corona effect on the edge of antenna and wing. Those phenomenon bring about performance degradation for radio communication and equipment operation. In this paper, the conditions such as climate, air vehicle's speed and frontal area were analyzed to design static dischargers. As a result, the static dischargers would be optimally designed for air vehicles and the performance of the static dischargers can verify according to the functional experiment. Therefore the result of this research will be used to make static discharger installation design for new air vehicle that have different size and mission.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.7
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• pp.539-549
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• 2017

In this paper, experimental studies on the shroud separation were performed to investigate characteristics of the shroud separation at mach 3. Shroud separation tests were carried out in the vertical free-jet wind tunnel that is capable of testing separable structures. A shroud model was miniaturized to meet test objectives and test section dimensions of the wind tunnel. Pneumatic Locking and separation mechanisms were designed considering external force due to free stream. High speed cameras were used to record the shroud motion and unsteady shock patterns over the deploying shrouds during the shroud separation process. Also, unsteady pressures on the nose surface were measured by using the pressure sensors. Through the tests, the measurement data necessary for researches on the shroud separation technology were obtained. Shroud separation behaviors and characteristics of unsteady pressure on the nose surface for each external flow conditions were analyzed.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.7
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• pp.610-617
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• 2017

In the recent weapon system trend, it is required to develop small and low cost guidance missile to track and strike the enemy target effectively. Controling the such small drone typed weapon demands a integrated electronic device that equipped with not only a wireless network interface, a high resolution camera, various sensors for target tracking, and position and attitude control but also a high performance processor that integrates and processes those sensor outputs in real-time. In this paper, we propose the android smartphone as a solution for that and implement the guidance and control application of the missile. Furthermore, the performance of the implemented guidance and control application is analyzed through the simulation.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.2
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• pp.89-97
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• 2020

In this study, a numerical analysis was performed on 26 inch single and coaxial propeller using the ANSYS Fluent 19.0 Solver to analyse the effect of the distance between coaxial propellers as one of the design parameter. The Moving Reference Frame (MRF) method was used for single propeller, while the sliding mesh method was used for a coaxial propeller to analyse the flow field varying with azimuth angle. The thrust and power are decreased as the upper and lower propeller approaching each other. As H/D is increased, interference between the propellers is decreased. According to the flow field variable contour of the coaxial propeller, it appears that the change in aerodynamic performance is due to the loading effect and the tip vortex wake effect.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.12
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• pp.1057-1064
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• 2014

The satellite on geostationary orbit accommodates multiple payloads into a single spacecraft platform and launched in June 26, 2010. The electrical power required to the satellite during sunlight is generated by a solar array wing. The solar cells are the GaInP/GaAs/Ge Triple Junction cells named Gaget2 cells from RWE Space, which were based on a Spectrolab epitaxy. This paper evaluates solar array power performance at end of design life based on the trend analysis results for the flight data on geostationary orbit. The estimated solar array power performance at end of design life compares with the power performance provided by solar array manufacturer. The solar cells show nominal behavior without significant degradation through the trend analysis results.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.10
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• pp.796-804
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• 2013

The "Potato Gun," a simple heat engine, is fabricated, tested and analyzed as a part of engineering education program of combustion and propulsion classes. Combustor pressure is predicted by the chemical equilibrium analysis of a constant volume combustor. Then, the internal ballistics, the conversion of thermal energy into the mechanical energy of a projectile, is predicted though the expansion process. The trajectory of a projectile is estimated by considering the aerodynamic effect around the spherical projectile. The energy conversion efficiency and the equivalence ratio of the fuel-air mixture could be estimated by the comparison of the experimental results and the theoretical prediction. The present work would be an example of attracting the interest of students for the application of the engineering principles at undergraduate level by recycling the waste materials.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.5
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• pp.357-365
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• 2013

In this study, forces and moments were measured on a projectile which consisted of a missile configuration body(shell) and a head installed control fins. The shell and the head were separated each other and the shell was rotated by an electric motor. The head rotated reversely against the rotational direction of the shell. The rotational force on the head was obtained from a couple of fixed fins of which angular displacement were set to the rotational direction equally. The air velocity was 40m/s on the experiment and the Reynolds number based on the diameter of head was $1.3{\times}10^5$. The other couple of fins were used to control the position and direction of the projectile by changing the angular displacement. From this experiment, the variation of force and moment were measured on the rotating projectile, and the effective amplitude and frequency were obtained through the FFT analysis.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.3
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• pp.230-236
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• 2018

This paper deals with the improvement of pressurized quality for high maneuver aircraft. Anti-G Valve is a pressure regulating valve for inflating anti-G suits and providing a sense line signal for a g-compensated oxygen regulator. The new anti-g valve system is satisfied with military specification MIL-V-87255 and allowed the pilots to tolerate high-G exposures without any vibrations. The flight test was performed by two T/FA-50 pilots and other tests used the centrifuge made by anti-g developer. A comparison of the new anti-g valve with period one, it have better response and low chattering phenomenon.