• Aerospace Industry
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• s.90
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• pp.44-47
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• 2006

• Proceedings of the Korea Information Processing Society Conference
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• 2010.11a
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• pp.1613-1616
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• 2010

본 논문은 실시간 운영체제인 Xenomai 를 사용하여, 회전익 무인항공기 소프트웨어 개발에 대한 내용을 설명하고 있다. 실시간 운영체제 사용하여 고정 순위 우선 스케줄링을 채택함으로써 데드라인의 타이밍(Timming) 결정성을 보장하였고, 이기종 시스템과의 호환성과 확장성을 고려하여 POSIX API 를 사용하여 멀티 쓰레드를 구현하였다. 또한 실시간 드라이버 모델(RTDM : Real-Time Driver Model)을 사용하여 획득한 데이터를 실시간 전송이 가능하도록 하였다. 본 논문은 실시간 운영체제를 무인항공기에 적용하고 구현된 비행제어 컴퓨터와 제어 소프트웨어를 비율 단조 스케줄링을 적용하여 무인항공기의 쓰레드들의 응답 속도 및 안정성을 보장하는 방안을 제시하였다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.9
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• pp.849-855
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• 2010

This paper investigated the roll lock-in phenomena of a canard-controlled missile with freely spinning tailfins by applying Falanga's roll-rate equation. To confirm and validate the accuracy of the results of the roll-rate and roll lock-in prediction for freely spinning tailfins, the results were compared with Blair's wind tunnel test data. For calculation of the roll-rate of freely spinning tailfins, rolling moment coefficients of the tailfins were obtained from the wind tunnel test data and roll-damping coefficients were calculated by missile DATCOM. The roll-rate and roll lock-in of the freely spinning tailfins were calculated by applying these values to the roll-rate equation for freely spinning tailfins. The calculation results showed good agreement with the wind tunnel test data, and the roll lock-in could be anticipated as well.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.1
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• pp.12-22
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• 2012

Performance variation of autorotating rotor was investigated. The shaft angle of the rotor is reduced while the flight velocity is increased. The BO-105 helicopter rotor blade was replaced by untwisted NACA 0012 airfoil and the rotor was simulated by using Transient Simulation Method(TSM) to judge the autorotation region for the variables. To simulate the compressibility effect at high speed flight, two-dimensional aerodynamic data was analyzed by compressible Navier-Stokes solver and Pitt/Peters inflow theory was adopted to simulate the induced velocity field. Thrust and lift coefficients, lift to drag ratio variations were investigated, also the lift and power were compared to those of BO-105 helicopter. Sharing lift and power between the autorotating rotor and wing was considered when the compound aircraft concept is introduced.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.6
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• pp.487-497
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• 2011

Numerical analysis has been performed to investigate the rotor speed and pitch range variations when the airspeed is increased in autorotation. Transient Simulation Method(TSM) was used to obtain the steady states of autorotation. The rotor blade was analyzed by the two-dimensional compressible Navier-Stokes solver in order to adapt to the airspeed increase and the results were used in the transient simulation method. Meanwhile, the Pitt/Peters inflow theory was used to supply the induced velocity fields. For the prescribed torque equilibrium state, the combinations of velocity, shaft angle, and pitch angle were produced to investigate the rotor speeds and variable ranges. The rotor tip Mach number and rotor speed were correlated and the trim range of pitch angle was observed with respect to the shaft angle decrease.

• Journal of Aerospace System Engineering
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• v.13 no.5
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• pp.39-48
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• 2019

The turbulent flow in the rotor-stator mixer is based on shear characteristics generated by the interaction of the stator with the rotor rotating at high speed. In this study, the flow characteristics analysis of the unsteady state generated by the interaction of the rotor and the stator in the prototype model of the emulsion-fuel related mixer development was performed with the MRF and SMM by applying the ANSYS FLUENT $k-{\varepsilon}$ (RKE) turbulence model. The behavior and shear characteristics of the flow particles generated at the interface between the designed rotor and stator, and trends such as velocity distribution and turbulence eddy dissipation, were predicted and verified using the CFD analysis.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.9
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• pp.20-24
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• 2006

Wind tunnel tests were conducted to compare gliding and turning performance of normal cruciform parachutes with newly modified cruciform parachutes. Modified cruciform parachute has better gliding performance than original cruciform parachutes but, modified cruciform parachute has worse turning performance than original cruciform parachute.

• Composites Research
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• v.20 no.3
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• pp.43-49
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• 2007

Dynamic instability of rotating disks is the most significant factor to limit its rotating speed. Application of composite materials to rotating disks may enhance the dynamic stability leading to a possible design of rotating disks with lightweight and high speed. Whereas much work has been done on the effect of transverse shear and rotary inertia, called Timoshenko effect, on the dynamic behavior of plates, there is little work on the correlation between the effect and the rotation of disk, especially nothing in case of composite disks. The dynamic equations of a rotating composite disk are formulated with the Timoshenko effect and the vibrational analysis is performed by using a commercial package MSC/NASTRAN. According to the results, the Timoshenko effect goes seesaw in some modes, unlike the well-known fact that the effect decreases as the rotating speed increases. And it can be concluded, based only on the present results, that decrement of the Timoshenko effect by disk rotation grows larger as the thickness ratio decreases, the diameter ratio increases, the modulus ratio increases, and the mode number increases.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.10
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• pp.894-900
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• 2012

The purpose of this research is to investigate the dynamic roll-damping characteristics of a spin-stabilized projectile in wind-tunnel testing. In the present work, the high-speed wind-tunnel tests for the roll-damping measurements were conducted on a finned spin-stabilized projectile model in the Agency for Defense Development's Trisonic Wind Tunnel at spin rates about 8,000 rpm. The test Mach numbers ranged from 0.6 to 0.9, and the angles of attack ranged from 0 to +15 deg. The evaluation of the bearing friction parameter was also conducted to eliminate the tare damping moment from the aerodynamic damping moment.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.10
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• pp.912-918
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• 2011

The purpose of this research is to determine the dynamic roll-damping data of a spinning projectile in wind-tunnel testing. In the present work, the high-speed wind-tunnel tests for the roll-damping measurements were conducted on a spin-stabilized projectile model in the Agency for Defense Development's Tri-Sonic Wind Tunnel at spin rates about 12,000 rpm. The test Mach numbers ranged from 0.7 to 1.05, and the angles of attack ranged from -4 to +10 deg. The validity of the wind-tunnel measurement techniques was evaluated by comparing them with the previous test results on the same configuration.