• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.821-825
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• 2005

Tilt rotor aircraft was developed for satisfying VSTOL (vertical short take off and landing) capability and cruise performance. However the noise generated by tilt rotor system causes one of the most serious problems. In this paper, noise characteristics of tilt rotor system in hovering flight are predicted by using free wake method and Lowson's formula. The flow field of the tilt rotor is simulated by using time marching free wake method, and the free field acoustic pressure is calculated through Lowson's formula. The predicted results are compared with experimental data at various observing positions. In the near field, they show good agreement with experimental data regardless of rotating speed and collective pitch angles of 6, 8 and 10 degree, although there are some discrepancies between prediction and experiment in the far field and at the rotating axis in the near field. It seems that the reason of these discrepancies is difference of unsteady force fluctuation between experiment and calculation.

• Journal of Aerospace System Engineering
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• v.3 no.2
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• pp.12-19
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• 2009

The research for the fatigue analysis is regarded greatly as important in aerospace field. Moreover, a study on the fatigue characteristic is very actively progressing. In this study, the fatigue life estimation was performed for Flaperon Joint which has FCL(fatigue critical location) of tilt-rotor UAV. The Flaperon Joint should be taken the various loads by several missions profiles of UAV. The fatigue load spectrum of Flaperon Joint is generated by the standard mission segment for the tilt-rotor UAV, and this spectrum is used for the fatigue test and analysis. The in-house fatigue analysis program is applied to calculate the fatigue life based on Stress-Life(S-N) method. The S-N curve is generated from the S-N data of Mil-Handbook by second order polynomial regression method. Moreover, the coefficient of determination is used to ensure how accuracy it has. In addition, the Goodman equation is used to consider the mean stress effect for evaluating more accurate fatigue life. Finally, the result of fatigue analysis is verified by comparing with the fatigue test result for the Flaperon Joint.

• Aerospace Engineering and Technology
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• v.9 no.1
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• pp.1-8
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• 2010

The tilt-rotor Smart UAV(Unmanned Air Vehicle) has been developed by KARI(Korea Aerospace Research Institute) for civil purposes. In order to prove the reliabilities of total system of Smart UAV, the series of ground tests were performed including system interface test, aircraft HILS(Hardware In the Loop Simulation) Test, ground power test, 4-DOF (Degrees of Freedom)rig test, and tethered hover test. Many unexpected problems occurred at each ground test. With clearing these problems, the total Smart UAV systems were matured and the airworthiness was proven enough. After complete of additional ground test proposed by FRRB(Flight Readiness Review Board), the first flight test will be performed in this year. This paper presents the procedures and the analysis results of the ground tests for the tilt-rotor Smart UAV.

• Journal of Aerospace System Engineering
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• v.18 no.1
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• pp.29-36
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• 2024

Recently, the concept of Urban Air Mobility (UAM) has expanded to Advanced Air Mobility (AAM). A tilt rotor type of vertical take-off and landing aircraft has been actively studied and developed. A tilt-rotor aircraft can perform a transition flight between vertical and horizontal flights. A blade pitch angle control system can be used for flight stability during transition flight time. In addition, Individual Blade Control (IBC) can reduce noise and vibration generated in transition flight. This paper proposed Disturbance Observer Based Control (DOBC) and Time Delay Control (TDC) for individual blade control of an Electro-Mechanical Actuator (EMA) based blade pitch angle control system. To compare and analyze proposed controllers, numerical simulations were conducted with DOBC and TDC.

• Composites Research
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• v.29 no.1
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• pp.16-23
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• 2016

In this paper, numerical results of sectional analysis, stress recovery and energy release rate were compared with the results of VABS, 3-D FEM through the blade analysis library. The result of stress recovery analysis for one-dimensional model including the stiffness matrix is compared with stress results of three-dimensional FEM. We discuss the configuration of the blade analysis library and compare verifications of numerical analysis results of VABS. Blade analysis library through dimensional reduction and stress recovery is intended to be utilized in conjunction with pre- and post-processing of the analysis program of the composite blade, high-altitude uav's wing, wind blades and tilt rotor blade.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.12
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• pp.819-828
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• 2022

Sensitivity of aircraft sizing depending on battery performance was studied for a generic quad tilt rotor type electric vertical takeoff and landing vehicle. The mission requirements proposed by Uber Elevate and NASA were used for initial sizing, and the calculated gross weight is ranged between 5,000lb and 11,000lb for battery specific energy range of 200-400Wh/kg in pack level and continuous discharge rate range of 4-5C. For the assumed gross weight of 7,000lb, the required battery performance was calculated with two different criteria: available power and energy, and the effects of battery specific energy and discharge rate are analyzed. The maximum discharge rate is also recommended considering failure cases such as one battery pack inoperative and one prop rotor inoperative.

• Aerospace Engineering and Technology
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• v.7 no.2
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• pp.31-37
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• 2008

Flight-test is necessary at the identification of dynamic model of flight vehicle. A commonly faced problem is that once the flight-test instrumentation system is difficult to reschedule in the vehicle at the end of the test. This paper identified the parameter of dynamic model of vehicle using measurement data of non-flight test. The identification algorithm is based on frequency response identification method (CIFER) dealing with a longitudinal motion of Smart UAV 40% scale.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.1000-1007
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• 2007

In this study, structural vibration analyses of a smart unmanned aerial vehicle (UAV) have been conducted considering dynamic hub-loads of tilt rotor. Practical computational structural dynamics technique based on the finite element method is applied using MSC/NASTRAN. The present UAV(TR-S5-04) finite element model is constructed as a full three-dimensional configuration with different fuel conditions and tilting angles for helicopter, transient and airplane flight modes. In addition, the 3-dimensional supporting equipment structures of electronic devices are considered for vibration analysis. As the results of this study, transient structural displacements and accelerations are presented in detail. Moreover, vibration characteristics of structural parts and installed equipments are investigated for different fuel conditions and tilting angles.

• Journal of Aerospace System Engineering
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• v.7 no.3
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• pp.65-69
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• 2013

Avionics system designed for the 200 kg-class tiltrotor UAV has been developed. Avionics system for the UAV is the reconstruct system and can be programmed automation controller. This paper focuses on the design aspects of the hardware and presents the ground and flight test results. The hardware aspects of the avionics system include details about the hardware configurations for the interfaces with the Digital Flight Control Computer, sensors and Line-replaceable unit modifications.

• 한국전산유체공학회:학술대회논문집
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• 2004.10a
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• pp.165-171
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• 2004

Smart UAV, which adopting tiltrotor aircraft concept, requires long endurance and high speed capability simultaneously These two contradictable flight performances are hard to meet with single wing concept and inevitably require the operation of flap system which should reveal optimal performance for each flight mode. In order to design SUAV flaperon satisfying the performance requirement, various configurations are generated and their aerodynamic performances are analyzed using numerical flow computations around flaps. Considering aerodynamic performance and manufacturing simplicity, a final flap configuration is selected.