• The Journal of the Convergence on Culture Technology
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• v.9 no.6
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• pp.941-946
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• 2023

To improve the lift, cruise speed, and range of eVTOL aircraft, which are being considered as future transportation vehicles, this paper introduces the concepts of Tilt Rotor and Tandem Wing to the aircraft. We developed an aircraft and conducted flight experiments to obtain flight videos and flight logs. The results of the analysis of the flight videos and flight logs showed that the aircraft's moment was excessively forward and the attitude was not recovered. To address this problem, we modified the wing incidence angles and surface areas in XFLR5 to obtain the optimal pitching moment coefficients to ensure vertical stability. We then analyzed the redesigned aircraft, developed using CATIA, through XFLR5. The results of this study provide valuable insights, suggesting that the incorporation of Tilt Rotor and Tandem Wing designs can contribute to achieving stable pitching moment coefficients. This innovative approach offers a promising avenue to significantly enhance vertical stability in UAM vehicles, paving the way for future advancements in the field.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.6
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• pp.483-488
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• 2007

The aerodynamic characteristics of FAST(Future Air Speed Transit) combined the body with tandem wing flying over nonplanar ground surface are investigated by using a boundary element method. To validate the present method, results of the present analysis are compared with the experiment and other numerical results. The arrangement of the tandem wing is determined to secure sufficient aero-levitation force and the stability through the analysis of the aerodynamic characteristics of the FAST. The FAST has the maximum lift characteristics when the tandem wing with lower endplate is located at the front side and the rear side of the body. The stability of the FAST can be secured by using the flaperon of the tandem wing.

• Journal of the Korea Society for Simulation
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• v.27 no.4
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• pp.19-26
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• 2018

The aerial launching UAV(Unmanned Aerial Vehicle) mainly uses a set of folding tandem wings to maximize flight performance and minimize the space required for mounting in a mothership. This folding tandem wing has a unique aerodynamic problem that is different from the general type of fixed wing aircraft, such as the rear wing interference problem caused by the wing of the front wing wake and vortex, and the imbalance of the pivot moment applied to the front and rear wings when the wing is deployed. In this paper, we have modeled and simulated various cases through computational fluid dynamics based on the finite volume method and analyzed various aerodynamic phenomena of the tandem wing type aircraft. We find that the front wing shall be installed higher than the rear for minimizing the wake influence and the rear wing can be deployed faster than the front because of the pivot moment due to aerodynamic forces. Also, considering the pivot moment due to aerodynamic force, the rear wing can be deployed much faster than the front wing. Therefore, it is necessary to consider it when developing the wing deploy mechanism.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.389-394
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• 2007

Numerical simulations are conducted to investigate the mechanism for force generation of an insect with tandem wing configuration. Various stroke amplitudes, stroke plane angles and phase difference between the fore- and hind-wings are considered. The Reynolds number is 150 based on the chord length and maximum translation velocity of the wing. When an insect requires high lift such as takeoff, it flaps its wings in parallel at a lower stroke plane angle and a bigger stroke amplitude than those in the hovering. With wings in counter-stroke, the lift fluctuations decrease, and moreover mean lift force decreases. Interactions among the fore-wing, hind-wing and vortices are examined to explain the force variations

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.1
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• pp.31-39
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• 2013

A Quad Tilt Wing UAV is a new concept hybrid UAV having the advantages of both fixed-wing and rotary-wing aircraft. This paper presents longitudinal flight dynamic characteristics of a Quad Tilt Wing UAV. The designed Quad Tilt Wing UAV is a configuration of a tandem wing type aircraft with an actuating motor and propeller mounted at each wing. Momentum theory is used to calculate the thrust, and nonlinear modeling is performed considering lift and drag generated by slip stream effect of propellers. Also, Force and moment variation at each tilting angle is considered. Static trim on longitudinal axis is analyzed via numerical simulation. Componentwise force contribution was analyzed at each trim mode. Dynamic characteristics were evaluated through eigenvalue analysis for a linear model at each flight mode. It is verified that longitudinal dynamic characteristics are changing from unstable to stable state by continuous transition of dominant poles.

• Journal of the Korean Society of Propulsion Engineers
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• v.8 no.4
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• pp.43-54
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• 2004

A visualization study was carried out to investigate the effects of phase difference qualitatively by examining wake pattern on the phase difference of a dragonfly type wing model. The model was built with scaled-up, flapping wings composed of a paired wing with fore- and hind-wings in tandem that mimick the wing form of a dragonfly. The present study was conducted by using the smoke-wire technique and an electronic device below the tandem wings was mounted to find the exact wing position angles. Uncertainties in wing position angle are about $\pm$$1.0^{\cire}$ and instantaneous wing positional angle varies from $-16.5^{\cire}$ to $+22.8^{\cire}$. The tests were made at phase differences between the fore-wing and hind-wing at $0^{\cire}$, $90^{\cire}$, $180^{\cire}$ and $270^{\cire}$. The results show that Karman vortex structures were produced at phase differences of $90^{\cire}$, $180^{\cire}$ and $270^{\cire}$, but Karman vortex structures were not observed at the phase difference of $0^{\cire}$.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.5
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• pp.605-611
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• 2011

In this study, based on previous studies, the thrust generated by using flapping tandem wings is examined. We studied on the relationship between the parameters for characterizing oscillatory tandem wings (namely, the Strouhal number and Reynolds number) for thrust generation in micro flow regime. At each Reynolds number, Strouhal number, heaving amplitude, distance between tandem wings, and phase difference are varied and the flapping motions of tandem mode are calculated to find the optimum conditions for generating thrust. As a result, comparing with a single flapping mode, we found that the minimum Strouhal number for generating thrust is shifted down up to approximately 25% when the tandem flapping mode is applied.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1586-1591
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• 2004

Flow visualization experiments have been performed to investigate the effects of phase lag, reduced frequency qualitatively by examining wake pattern on a dragonfly type wing. The model was built with a scaled-up, flapping wings, composed of paired wings with fore- and hindwing in tandem, that mimicked the wing form of a dragonfly. The present study was conducted by using the smoke-wire technique, and an electronic device was mounted to find the exact positional angle of wing below the tandem wings, which amplitude is ranged from $-16.5^{\circ}$ to $+22.8^{\circ}$. Phase lag applied on the wings is $0^{\circ}$, $90^{\circ}$, $180^{\circ}$ and $270^{\circ}$. The reduced frequency is 0.15, 0.3 and 0.45 to investigate the effect of reduced frequency. It is inferred through observed wake pattern that the phase lag clearly plays an important role in the wake structures and in the flight efficiency as changing the interaction of wings. The reduced frequency also is closely related to wake pattern and determines flight efficiency.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.2
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• pp.81-89
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• 2019

In this study, wind tunnel test on Quad-Tilt Propeller which has tandem wings is carried out to analyze the aerodynamic interference effect of front wing and propeller on rear wing during forward flight. Using 6-axis balance system, forces and moments of whole aircraft were measured and using strain gauge at wing root, bending moments were measured to observe change of aerodynamic force of each wings. A 12-hole probe was used to measure the flow field in the wing and propeller wake. Flow characteristics were observed qualitatively through flow visualization experiment using tuft and smoke. To measure the aerodynamic interference by elements, the influence of front wing and propeller on rear wing was analyzed by changing the wings and propellers mount combination.

• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.4
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• pp.443-450
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• 2014

In this study, we have discussed about the effect of hydrofoil arrangement and longitudinal moment characteristic on longitudinal motion stability of fully-submerged hydrofoil by the experiment of tandem hydrofoil model. First of all, tandem hydrofoil model that has canard wing arrangement has been made and characteristics of lift force and drag force by performing the lift force and drag force measuring experiment has also been estimated. Besides, tandem hydrofoil model's wing arrangement which has the initial stability and self stability of longitudinal motion has also been determined. In longitudinal stability experiment of tandem hydrofoil model, the motion characteristic of pitch and heave and the longitudinal stability of foil borne condition by variation of self stability of longitudinal moment and longitudinal distance are estimated. The result from the experiment and it's important conclusion can be described as below; Increase the self stability for longitudinal moment, the higher self stability for pitch motions in a constant pitch angles. By increasing the self stability for longitudinal moment, the range of fluctuation of pitch motion and heave motion for pitch angle also will change relatively small and longitudinal stability is excellent. Lastly, when the lift force of hydrofoil is remain constants, we can conclude that securing the enough self stability for longitudinal moment is essential for stable foil borne condition of tandem hydrofoil.