• International Journal of Aeronautical and Space Sciences
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• 제14권3호
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• pp.210-214
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• 2013

The sensitivity of transonic flow past a Whitcomb airfoil to deflections of an aileron is studied at free-stream Mach numbers from 0.81 to 0.86 and vanishing or negative angles of attack. Solutions of the Reynolds-averaged Navier-Stokes equations are obtained with a finite-volume solver using the $k-{\omega}$ SST turbulence model. The numerical study demonstrates the existence of narrow bands of the Mach number and aileron deflection angles that admit abrupt changes of the lift coefficient at small perturbations. In addition, computations reveal free-stream conditions in which the lift coefficient is independent of aileron deflections of up to 5 degrees. The anomalous behavior of the lift is explained by interplay of local supersonic regions on the airfoil. Both stationary and impulse changes of the aileron position are considered.

• 항공우주시스템공학회지
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• 제16권6호
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• pp.114-122
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• 2022

본 논문에서는 CFD 기법을 활용하여 전기체 형상의 투척식 무인기 형상에 대해 고속 회전하는 프로펠러와 그로 인해 생성된 후류 간섭 효과를 고려한 비정상 유동해석을 수행하였다. 또한 다양한 투척식 이륙 조건에서 롤 모멘트 평형에 요구되는 에일러론 타각을 정확하게 예측하기 위해 실제 조종면 회전을 고려한 유동해석이 수행되었다. 투척식 소형 무인기의 경우 초기 이륙상태에서 롤 안정성을 증대시키기 위해 적절한 초기 에일러론 설정을 활용하는 것이 유용한 방식이며, 구축된 공력 데이터베이스를 사용하여 다양한 이륙속도와 받음각 조건들에 대해 롤 모멘트를 상쇄시킬 수 있는 에일러론 타각 조건들이 빠르게 예측 가능함을 보였다.

• 한국항공우주학회지
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• 제32권5호
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• pp.18-23
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• 2004

한 러 풍동시험 기술협력사업의 일환으로 러시아 TsAGI T-012 풍동에서 KARI가 보유하고 있는 전진익형 항공기 모델에 대한 풍동시험을 수행하였다. Wire-suspension 모델지지부를 사용하고 있는 T-102 시험결과와 KARI 3점지지부 및 2 점지지부 시험결과를 비교하였다. 항력의 경우 KARI 시험결과와 TsAGI T-102 시험결과는 매우 좋은 일치성을 보이고 있다. 조종면에 의한 영향을 비교한 결과 두 기관의 시험결과는 요잉모멘트와 롤링모멘트에서도 매우 좋은 일치성을 보이고있다.

• 항공우주시스템공학회지
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• 제6권3호
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• pp.24-28
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• 2012

An actuator should be added to a existing control linkage to make manned aircraft to unmanned. But it is quiet difficult to synchronize actuator with control surface because non-linear error necessarily occurs when four-bar linkage acts in three dimensional motion. In addition, in point of controller design view, while a real-time model needs the control surface deflection as its input, controller needs the actuator command as its output. Hence, the relation between both should be investigated. In this paper, the mathematical relation between actuator and control surface deflection investigated by kinematic analysis of a plant aircraft. The performance margin of the selected actuator also was verified.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.537-541
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• 2003

In order to control the missiles by aerodynamics, control surfaces sometime called fins are used. Deflection angles of these fins are the right control variables of the aerodynamics, but aerodynamicists prefer to use analytic variables called aileron, elevator and rudder instead of these physical variables, because these three analytic variables dominantly influence on the roll, pitch and yaw channels of the missile maneuver, respectively, and each can be assumed a linear combination of four fin deflection angles. On that basis, roll, pitch and yaw autopilots for controlling the attitudes or lateral acceleration of the missile are designed, and as a consequence outputs of each autopilot are aileron, elevator and rudder commands, respectively. In the existing fin control scheme for the typical tail-fin controlled cruciform missiles, firstly these outputs are distributed to four fin defection commands, and after that four fins are actuated by fin controllers so that their deflections follow the commands. This paper shows that performance of such control schemes can be degraded significantly when fin actuators have certain physical constraints such as slew rate, voltage or current limit, uncertainty of actuator dynamics, and so on, and propose a new control scheme which alleviates such problems. This scheme can be widely applied to various fin actuation systems. But in this paper, for convenience, tail-fin controlled cruciform missile is taken as an example, and it is shown that a proposed control scheme gives better performance than the existing one.

• 대한기계학회논문집B
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• 제30권10호
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• pp.1012-1018
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• 2006

To evaluate the aerodynamic efficiency of TR-S4 configuration, wind tunnel tests of 40% scaled model were done in KARI LSWT. TR-S4 configuration has different nacelle shape, larger EO/IR camera and aftward wing location compared with TR-S2. Component build-up test after adding each element of model is performed. Also effects of horizontal tail incidences, Flaperon and Aileron deflection. on aerodynamic characteristics are measured. Test results showed that TR-S4 configuration has favorable stability characteristics in longitudinal, lateral and directional for the pitch and yaw motions.

• 대한기계학회논문집B
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• 제28권7호
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• pp.800-808
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• 2004

Wind tunnel test of an airplane model with forward swept wing was done in KARI LSWT to evaluate and measure the aerodynamic characteristics of initially designed configuration. Since the given wing planform did not fully satisfy the design requirements, local flow control devices such as vortilon, vortex generator and flow fence were used to delay separation and to enhance aerodynamic characteristics. Also decision making processes of design parameters such as vertical tail boom length, the location, size and the incidence angle of horizontal tail were discussed. The general aerodynamic characteristics of forward swept wing for various control surface deflection conditions of flap, aileron and elevator were also given.

• Smart Structures and Systems
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• 제3권1호
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• pp.89-114
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• 2007

Two aspects of the design of a small-scale smart wing are addressed in this work, related to the ability of the wing to modify its cross section assuming the shape of two different airfoils and to the possibility of deflecting the profiles near the trailing edge in order to obtain hingeless control surfaces. The actuation is provided by one-way shape memory alloy wires eventually coupled to springs, Shape Memory Alloys (SMAs) being among the most promising materials for this kind of applications. The points to be actuated along the profiles and the displacements to be imposed are selecetd so that they satisfactorily approximate the change from an airfoil to the other and to result in an adequate deflection of the control surface; the actuators and their performances are designed so that an adequate wing stiffness is guaranteed, in order to prevent excessive deformations and undesired airfoil shape variations due to aerodynamic loads. The effect of the pressure distributions, calculated by way of the XFOIL software, and of the actuators loads, is estimated by FE analyses of the loaded wing. Two prototypes are then realised incorporating the variable airfoil and the hingeless aileron features respectively, and the verification of their shapes in both the actuated and non-actuated states, supported by image analysis techniques, confirms that interesting results are achievable with the proposed lay out and design considerations.